<![CDATA[Applied Clinical Radiology: Long Reads]]>https://appliedclinicalradiology.substack.com/s/full-length-articleshttps://substackcdn.com/image/fetch/$s_!Jydu!,w_256,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F98b6b0a7-1315-4b4c-800a-864d025d81b1_672x672.pngApplied Clinical Radiology: Long Readshttps://appliedclinicalradiology.substack.com/s/full-length-articlesSubstackSun, 26 Apr 2026 13:53:37 GMT<![CDATA[The Radiology Report as a SOAP Note]]>https://appliedclinicalradiology.substack.com/p/the-radiology-report-as-a-soap-notehttps://appliedclinicalradiology.substack.com/p/the-radiology-report-as-a-soap-noteTue, 25 Nov 2025 18:26:13 GMTSynopsis

  • The four sections of a SOAP note can be seen within the radiology report.

    • Subjective = Indication and history. This is what the radiologist hears and will include other information from secondary sources such as comments made by the technologist performing the exam.

    • Objective = Findings. This is what the radiologist sees.

    • Assessment = Impression. This is what the radiologist thinks about what they see.

    • Plan = Recommendations within the Impression section. This is what the radiologist recommends based on what think is in the differential diagnosis.

  • Like the Assessment and Plan sections of the SOAP note, the Impression section of the radiology report should include items that require clinical action. For the ordering provider, this is the most valuable portion of the report, which guides the provider in developing the care plan without minutia that distract from the patient’s care.

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Context of the Radiology Report

The radiology report as a medical document was born shortly after the use of radiographs became part of the diagnostic workup in the early 1900s. In 1904, Preston Hickey introduced the term interpretation to define the process of rendering radiographic findings and creating a differential diagnosis.

The major purpose of the radiology reports is to guide clinical decisions by providing accurate, actionable information to the care team and patient. Preston argued for standardized nomenclature and a standardized report comparable to pathology reports, but this has been a challenge in a field driven by ever changing technology. However, the radiology report has evolved over time to include standard data including the patient information, description of the exam being performed, the facility at which the exam was obtain, and several other pieces of information for various purposes. Standards for radiology reporting and expectations of communication have been defined.

The radiology report and the SOAP note serve the common purpose of clear clinical documentation and have several parallels. The radiology report is divided into sections, which usually include the (1) indication/history, (2) findings, (3) impression, and (4) recommendations. These four parts have a close parallel to the (1) subjective, (2) objective, (3) assessment and (4) plan sections of a SOAP note. Let’s look at the comparison.

Subjective = Indication: What the radiologist hears

The indication and information from the radiology technologist are comparable to the subjective section of a SOAP note in that they are both secondhand sources of information, indirectly communicated from the patient to the radiologist.

Further, the indication is frequently a general complaint, such as chest pain, headache, or abdominal distention, without the details contained in a SOAP note or the history and physical. Generic indications provide little context for a radiologist when interpreting a diagnostic exam. Advances in EMR and PACS integration allows radiologists to readily look into the patient’s chart for relevant details when needed for interpretation, but a well written indication facilitates radiology turnaround time to the final report.

The introduction of drop-down pick lists has led to some ordering providers simply choosing from the list; a simple mis-click can make the indication erroneous. If the pick list doesn’t contain the relevant indication, the closest alternative may be selected, which can be misleading to the radiologist. Other times the indication is selected to get the exam through the gauntlet of insurance filters to guarantee that the exam will be performed. For these reasons, radiologists view the indication as subjective information.

Objective = Findings: What the radiologist sees

The findings described in the body of the report directly correlate to other objective data recorded the objective section of the SOAP note. Rather than vital signs, physical exam findings, and lab results, the radiologist will discuss radiographic anatomy and pathology. Depending on the exam, the radiologist will comment in echogenicity on ultrasound, attenuation on radiographs and CTs, changes in signal on MRI, and radiotracer uptake on nuclear medicine studies. When comparing to a prior exam the radiologist will discuss increasing size or decrease density of a mass lesion. Using the appropriate descriptors for the finding is critical in the interpretation of a diagnostic imaging exam.

Radiologists should consistently strive to use standard descriptive terms, especially when a reporting paradigm exists, such as the breast imaging reporting and data system (BIRADS) for mammography, lung reporting and data system (Lung-RADS) for lung cancer screening, the American Association for the Surgery of Trauma (ASST) scales for solid organ injury in a trauma patient, etc. Consistent use of standard descriptive terms increases accuracy, clarity and confidence in the report. Also, structured reporting and standardized descriptive terms allow the use of large language models for performance improvement and research purposes.

The field of radiology has moved from free-style prose to a structured reporting format in the findings section. This has increased efficiency in creating and reading a report, increased clarity and understanding of the findings, and decreased the frequency of reporting errors.

The technique section is also objective data, used by radiologists to define the body part imaged, describe the modality and protocols used for the exam and can provide assessment of the quality of an exam. This information establishes the environment of the entire report. The technique section is often used by insurance payors to support fees for the exam.

Assessment = Impression: What the radiologist thinks about the findings.

The impression section of the report is directly comparable to the assessment portion of a SOAP note. The radiologist takes the subjective information and the objective findings to render their impression of what these mean. Lack of clarity on the indication can lead to misinterpretation of the findings. Suboptimal imaging can lead to vague impressions. An inaccurate descriptor can result in an incorrect impression.

Like the Assessment section of the SOAP note, the Impression section of the radiology report should include items that require clinical action. For the ordering provider, this is the most valuable portion of the report, which guides the provider in developing the care plan without minutia that distract from the patient’s care. Details of the findings and chronic conditions not requiring active management are usually kept in the Findings section.

[insert examples]

Plan = Recommendation: What the radiologist thinks the next step should be.

While the recommendations may not be a separate section of the report, after the differential diagnosis is rendered, the radiologist considers what should the next step in management be for this patient. Recommendations are usually within the impression, paired with the differential diagnosis for a finding or constellation of findings.

For example, a CT brain without contrast is the initial exam performed in a patient with symptoms suggesting a stroke. While that exam may demonstrate findings that indicate that there is an ischemic stroke, other exams are needed to qualify the diagnosis, such as a CTA of the head and neck to assess for stenosis or emboli as the etiology of the stroke, and MRI can be used to show the extent and age of a stroke. The CTA of the head and neck is usually part of the stroke workup protocol. However, the radiologist may recommend the MRI of the brain at the time of the CT exams if these do not provide a full explanation of the patient’s symptoms.

Combining the concepts of assessment and plan into the impression section makes it the most clinically relevant section of the radiology report. And as with the SOAP note, not all subjective and objective comments are included in the impression section. The impression section should only include items that would prompt clinical action. For the ordering provider, this is the most valuable portion of the report, and many will only read this portion in its entirety.

Final Thoughts

The radiology report is a focused consultation that offers expert opinion, one radiologic exam at a time. Whereas the SOAP note documents every aspect of a patient encounter for longitudinal, multidisciplinary patient care. The referring provider integrates the radiology report into their SOAP note, ultimately using the radiologist’s “Objective” findings and “Assessment and Plan” (Impression with differential diagnosis and recommendations) to formulate the final, global assessment and treatment plan.

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Cite This Post

McQuiston, SA. (2025 NOV 25). The Radiology Report as a SOAP Note. Applied Clinical Radiology. https://appliedclinicalradiology.substack.com/publish/post/187779076

References

Legal Medical Disclaimer

The information provided in this newsletter is for informational and educational purposes only. The content is based on publicly available research, general health knowledge, and is not tailored to any person’s specific health circumstances. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. The use of this newsletter does not create a doctor-patient relationship between you and the author(s) or publisher. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Do not disregard professional medical advice or delay in seeking it because of something you have read in this newsletter

]]><![CDATA[A Tale of Two Sisters]]>https://appliedclinicalradiology.substack.com/p/a-tale-of-two-sistershttps://appliedclinicalradiology.substack.com/p/a-tale-of-two-sistersFri, 17 Oct 2025 15:28:54 GMTI had two half-sisters who had breast cancer…one from my dad’s first marriage, one from my mom’s first marriage. I am the only child of their last marriage. These two sisters were not genetically related to each other.

Doris, my oldest sister, found a breast lump during her self-exam. She went to her doctor, had a mammogram, and was referred to a breast surgeon. At nearly 60 years of age, she was diagnosed with stage I invasive ductal adenocarcinoma. She had a lumpectomy. I’m not sure whether she had chemotherapy or radiation therapy. I suspect she did. She lived to be 94 years old without recurrence of her breast cancer.

Leela, my youngest sister, found a breast lump during a self-exam. She was afraid of it being cancer and hoped that it would just go away. It didn’t.

Eighteen months after finding the lump, she came to me the day after Christmas saying, “Sam, I have a doctor’s appointment next month for my blood pressure, but there is something else I think I need to talk with him about.”

“Lee, what’s up?”

She lifted her blouse and bra. I didn’t need to do a physical exam. I could see the mass. There was a large bulge just to the right side of her sternum. At first, I didn’t think breast cancer; the mass was so medial that my first thought was a chest wall lesion. Maybe a sarcoma. I hoped it was a lipoma. On palpation, it was firm and nontender. I had to control my tears and encourage her to get into her doctor as soon as possible.

When she went for her appointment, her doctor immediately called a breast surgeon, and they were able to see her that day. Her biopsy returned invasive ductal carcinoma.

Her work up revealed liver lesions that were never biopsied but went away when she had neoadjuvant chemotherapy, presumed to be metastases. She had 11 of 19 nodes positive for cancer at her mastectomy. She was diagnosed at 44 years old with stage IV breast cancer. After a two-year fight with the disease, she died at 46 years of age.

Two sisters. Same disease. The difference? One found a lump on self-exam and did something about it immediately. She lived over 30 years as a breast cancer survivor. The other found a lump on self-exam and fear kept her from acting. She succumbed to breast cancer after 2 years.

I wear two pink ribbons on my white coat, one in memory of each of my sisters. People often ask why I have 2 of the same lapel pins. I tell them these 2 stories and end the explanation of my 2 pink ribbons with this…

The difference between my two sisters is clear. My oldest sister’s action saved her life. My youngest sister’s fear took her life.

A palpable breast lump must be evaluated with a mammogram as soon as possible. We cannot let fear get in the way of taking care of ourselves.

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Breast Self-Exam (BSE)

As a radiologist with 2 sisters who had breast cancer, October – Breast Cancer Awareness Month – holds a particularly special place for me. It’s crucial to clarify that the current guidelines from major organizations often emphasize the importance of breast exams by a physician or advanced practitioner and mammography for screening. Guidelines don’t always recommend the formal, monthly breast self-exam (BSE) as the primary screening tool, because studies haven’t conclusively shown that the monthly BSE alone lowers overall breast cancer mortality.

However, this does NOT mean the BSE should be ignored!

As a radiologist, I see countless cases of cancer, and in a significant number of them, the patient was the first person to detect the nodule/mass. Knowing your own body is a powerful health tool. Physical self-awareness is crucial, which includes incorporating regular self-checks into your routine. For example, when you shower, check yourself.

Mammogram Recommendations

Why are Mammograms Recommended?

The primary goal of mammography is early detection, inducing a stage shift. I previously discussed the concept of a stage shift in my post on Lung Cancer Screening. Finding a stage 1 cancer and treating it results in better outcomes than finding a stage 4 cancer. When breast cancer is found early, it’s often smaller and has not spread, making it easier to treat successfully. Regular mammograms have been shown to reduce breast cancer mortality by detecting cancer earlier. Getting started in a routine of having regular mammograms has been proven to have significant positive impact on outcomes when cancer is found.

Who Should Get Screened and When?

This is where it can sometimes get a little confusing, as different organizations have slightly varying guidelines. It’s always best to discuss your individual risk factors and family history with your doctor to determine the most appropriate screening schedule for you.

The following recommendations for mammogram screening are based on the current guidelines from the American College of Radiology (ACR), the American Cancer Society (ACS), the American College of Obstetricians and Gynecologists (ACOG), and the U.S. Preventive Services Task Force (USPSTF).

Age to Start Screening

  • ACS and ACOG recommend that women at average risk for breast cancer begin annual mammograms at age 40.

  • USPSTF recommends that women at average risk begin biennial (every 2 years) mammograms at age 40.

  • ACR breast cancer screening guidelines call for all women — particularly Black and Ashkenazi Jewish women — to have risk assessment by age 25 to determine if screening earlier than age 40 is needed.

Frequency of Screening

  • ACR, ACS and ACOG recommend annual mammograms for women ages 45-74.

  • USPSTF recommends biennial mammograms for women ages 40-74.

  • Women 75 and older should discuss screening with their healthcare provider.

    • A shared-decision conversation should include the topics of life-expectancy and comorbidities.

    • If breast cancer is identified, does the patient have the ability and desire to undergo treatment? Treatment may include surgery, chemotherapy, and/or radiation.

Other Considerations

  • Women with a personal or family history of breast cancer, dense breasts, or other risk factors may need more frequent screening.

  • It’s important that physicians discuss patient’s individual risk factors and screening options with each patient.

  • Mammograms can detect breast cancer early, when it’s most treatable.

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Cite This Post

McQuiston, SA. (2025 OCT 17). A Tale of Two Sisters: Part 1. Applied Clinical Radiology. https://appliedclinicalradiology.substack.com/publish/post/176333852

Additional Resources:

Legal Medical Disclaimer

The information provided in this newsletter is for informational and educational purposes only. The content is based on publicly available research, general health knowledge, and is not tailored to any person’s specific health circumstances. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. The use of this newsletter does not create a doctor-patient relationship between you and the author(s) or publisher. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Do not disregard professional medical advice or delay in seeking it because of something you have read in this newsletter

]]><![CDATA[Contrast Media, Myths and Management ]]>https://appliedclinicalradiology.substack.com/p/contrast-media-myths-and-managementhttps://appliedclinicalradiology.substack.com/p/contrast-media-myths-and-managementThu, 02 Oct 2025 17:00:25 GMTSynopsis

  • Allergy to iodine is incompatible with human life. Iodine is required for thyroid hormone synthesis, which is vital for normal human physiologic function.

  • Cross reactivity between iodinated contrast media (ICM) and other substances does not create clinical concern for a reaction to ICMs; it is the tendency to have allergies that creates the clinical concern, i.e. atopy.

  • When a patient says, “I am allergic to iodine,” we need to qualify the details of their allergy. Consider the questions…

    • What happened when you had the allergic reaction?

    • Did your reaction occur after you ate something? What did you eat/drink?

    • Did you reaction occur after you took a medicine?

    • If the reaction occurred as part of an imaging exam, what kind of contrast were you given? Was it for a CT? An MRI? An angiogram? Was it after oral contrast? After IV contrast?

    • What symptoms did you have? Itching? Rash? Shortness of breath? Scratchy throat?

    • What were you given to treat the reaction? Steroids? Benadryl?

    • Were you intubated?

  • Accurate documentation of a patient’s allergy is vital for patient safety.

    • For example, hospital food services needs to know that they have a food allergy.

    • Radiology needs to know what ICM induced the allergic reaction and what symptoms occurred. Radiology can avoid use of that agent.

    • Avoid using the misnomer “iodine allergy”.

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Case Presentation

A 67-year-old female presents for contrasted CTs of the chest, abdomen, and pelvis for breast cancer staging. The medical record states that the patient is “allergic to iodine,” but has not received pre-medication prophylaxis. Can the radiologist proceed with the exam? If not, what steps need to precede performance on the contrasted CT scans.

Objectives

  • Understand why the misnomer “iodine allergy” should not be used

  • Identify factors that may predict a reaction to contrast media

  • Accurately document clinically relevant allergies

Vocabulary

  • Allergen, Allergy

  • Atopy

  • Cross reactivity

  • Iodinate-contrast media (ICM)

Background

In 2023, approximately 93 million CT scans are performed annually in the United States. Data from a large-scale 2022-2023 study of a U.S. healthcare system shows that between 52.7% and 57.7% of all CT exams were performed with intravenous contrast.

It’s Elemental, Dr. Watson.

Iodine is an atom. It sits right next to xenon on the periodic table. Iron, oxygen, lead, and barium are atoms as well. Allergy to any of these elements is not possible; they are too small and simple to be allergenic. Imagine being allergic to iron or oxygen! In over 20 years of practicing radiology, I have never come across a patient with a “barium allergy” or a “xenon allergy.” We have routinely used these 2 elements in radiology for many decades.

Elemental iodine is a required trace element in the human diet. We consume iodine in various foods, such as seafood, Greek yogurt, milk, eggs, enriched breads, seaweed, liver, etc. In the United States, iodine is added to table salt to prevent iodine deficiency. Iodine deficiency affects about two billion people worldwide and is the leading preventable cause of intellectual and developmental disabilities.

Iodine is an essential component of thyroid hormones, including triiodothyronine (T3) and thyroxine (T4). There are 3 iodine atoms on T3 and 4 atoms on T4 as highlighted in red in the image below. Low levels of T3 and T4 induce the pituitary gland to release thyroid-stimulating hormone (TSH, AKA thyrotropin), which stimulates the thyroid gland to increase the uptake of iodine and stimulates the synthesis and release of T3 and T4. Thyroid hormones are necessary for many physiological processes, including growth, development, metabolism, body temperature, and heart rate.

Iodine is needed to synthesize thyroid hormones; thyroid hormones are needed for normal physiologic functions. An allergy to iodine is not compatible with normal human life.

What The Shell?

Once computed tomography with iodinate contrast media (ICM) became widely used in the 1970s and 1980s, we learned that ICM causes an allergic-like reaction. The pathogenesis of these reactions is often unclear. Patients who have experienced an allergic-like reaction to ICMs may or may not have developed immunoglobulin E (IgE) antibodies to the ICM that they were given. Unless is it know that the patient has antibodies to an ICM, it is preferred to refer to these reactions as “allergy-like” rather than to call them an allergy.

It is also unclear how the association between reactions to ICMs and shellfish allergy began. Reports from the 1970s looked at patients with allergic-like reactions, but many of these reports discussed food allergies, not just seafood allergy. With iodine being one common element in both shellfish and ICMs, some speculated that the connection of a shellfish allergy to an ICM reaction was born from the assumption that this common denominator was the inciting component.

Shellfish allergy is due to IgE to tropomycins (actin-binding proteins in muscle). It was speculated that some ICMs had a structure similar to tropomycin, which prompted cross reactivity between ICMs and shellfish. However, allergic-like reactions to ICMs are most often a hyperosmolar reaction rather than an IgE-mediated reaction.

Patient Factors Affecting Administration of ICMs

Cross reactivity between iodinated contrast media (ICM) and other substances does not create clinical concern for a reaction to ICM administration; it is the tendency to have allergies in general that creates the clinical concern. The tendency to be allergic, whether it is a food intolerance, seasonal rhinitis, povidone dermatitis, drug allergy, or sensitivity to any other allergen, is the most accurate predictor of a person having an allergic-like reaction to ICMs…in a word, “atopy.”

Atopy is the genetic predisposition to develop allergic conditions, such as allergic rhinitis, asthma, and eczema (atopic dermatitis). People with atopy have an exaggerated immune response to common environmental substances like pollen or dust mites. Their immune system responds with production of IgE. When exposed to allergens, their immune system reacts, leading to the development of the allergic conditions. Atopy increases the risk of a reaction to ICM administration; no specific allergy is more likely to prompt a reaction to contrast media.

Management

When a patient says, “I am allergic to iodine,” we need to qualify the details of their allergy. Consider the questions…

  • What happened when you had the allergic reaction?

  • Did your reaction occur after you ate something? What did you eat/drink?

  • Did you reaction occur after you took a medicine?

  • If the reaction occurred as part of an imaging exam, what kind of contrast were you given? Was it for a CT? Was it for an MRI? What is after oral contrast? After IV contrast?

  • What symptoms did you have? Itching? Rash? Shortness of breath?

  • What were you given to treat the reaction? Steroids? Benadryl?

  • Were you intubated? Were you put in the ICU?

The radiologist must have clarification of the patient’s allergy if the medical record states that they are “allergic to iodine” before iodinated contrast media can be administered. Accurate documentation of a patient’s allergy is vital for patient safety. For example, hospital food services need to know that the individual has a food allergy to avoid giving them that food/drink. Whereas radiology needs to know what ICM induced the reaction and what symptoms occurred. Radiology can avoid use of the offending agent.

We need to avoid the use of the misnomer “iodine allergy.” Continued use of the expression propagates the myth. It is very important that we use appropriate descriptions of a patient’s allergies in our discussions about the patient’s care.

Note: Description and management of contrast reactions, including pre-medication prophylaxis and treatment of reactions to ICMs, will be discussed in a subsequent post.

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Case Presentation Restated

A 67-year-old female presents for contrasted CTs of the chest, abdomen, and pelvis for breast cancer staging. The medical record states that the patient is “allergic to iodine,” but has not received pre-medication prophylaxis.

Question

Can the radiologist proceed with the exam? If not, what steps need to precede performance on the contrasted CT scans.

Answer

No, the radiologist must have clarification of the patient’s allergy before iodinated contrast media can be administered. While the radiologist could interview the patient to illicit the accurate history, it would be best for the patient’s primary care provider to correct the medical record. The “iodine allergy” would need to be removed, and the correct allergen and the patient’s specific symptoms entered into their medical record.

Cite This Post

McQuiston, SA. (2025 OCT 02). Contrast Media, Myths and Management: Part 1 - “Iodine Allergy.” Applied Clinical Radiology. https://appliedclinicalradiology.substack.com/publish/post/174301194

Additional Resources and References

Video Resources

Legal Medical Disclaimer

The information provided in this newsletter is for informational and educational purposes only. The content is based on publicly available research, general health knowledge, and is not tailored to any person’s specific health circumstances. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. The use of this newsletter does not create a doctor-patient relationship between you and the author(s) or publisher. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Do not disregard professional medical advice or delay in seeking it because of something you have read in this newsletter

]]><![CDATA[Imaging in Pregnancy]]>https://appliedclinicalradiology.substack.com/p/imaging-in-pregnancyhttps://appliedclinicalradiology.substack.com/p/imaging-in-pregnancyFri, 19 Sep 2025 20:33:14 GMTSynopsis

  • Diagnostic imaging in a pregnant patient presents 2 primary risks, i.e. the potential effects of ionizing radiation and the safety of contrast agents.

    • All diagnostic imaging uses energy from across the electromagnetic spectrum, but CT, radiographs, nuclear medicine, mammography, and conventional angiography uses ionizing radiation, which has enough energy to remove electrons from atoms, creating ions. The ions function as free radicals, causing damage to genetic and biological tissues.

    • If possible, consider ultrasound or MRI without contrast for initial diagnostic imaging needs.

    • Iodine-based contrast media (ICM) is generally considered safe in pregnancy, though they do cross the placenta.

    • Gadolinium-based contrast agents (GBCA) are avoided in pregnancy unless essential for the diagnosis, and the benefit clearly outweighs the potential risks.

  • The American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG) recommend that explicit, and often written, informed consent be obtained for any CT scan where the fetus is in the primary beam.

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Case Presentation

A 25-year-old pregnant patient presents with abdomen pain. What are the risks associated with imaging during pregnancy? What are the most appropriate initial diagnostic imaging modalities of choice? When is informed consent obtained before imaging a pregnant patient?

Objectives

  • Identify risks associated with diagnostic imaging modalities used during pregnancy.

  • Determine the most appropriate and safest diagnostic imaging modalities to use in common clinical scenarios during pregnancy.

  • Understand the fundamental principles governing radiation exposure and contrast media use in pregnancy.

  • Develop a clinical approach to managing imaging needs in pregnant patients, including appropriate counseling and informed consent.

Vocabulary

  • ALARA principle

  • Free radical

  • Gadolinium-based contrast agent (GBCA)

  • Iodine-based contrast media (ICM)

  • Ionizing radiation

  • Non-ionizing radiation

  • Organogenesis

  • Teratogenesis

Background

Pregnancy does not exclude patients from disease processes that are not related to pregnancy, may make a patient more susceptible to some conditions (pulmonary thromboembolism, infection), and may exacerbate preexisting conditions (diabetes, high blood pressure). So, it is imperative that those caring for pregnant patients have a fundamental understanding of the use of diagnostic imaging during this pivotal time in their life.

A retrospective study from 1996 to 2016 showed that over the 20-year period, diagnostic imaging rates during pregnancy increased by 38%, from 34.5/1000 in 1996 to 47.6/1000 in 2016 in the United States. This is a significant change which parallels the general increased use of diagnostic imaging in other patient populations.

Risks of Imaging during Pregnancy

Diagnostic imaging in a pregnant patient presents 2 primary risks…

  1. The potential effects of ionizing radiation

  2. The administration of contrast agents

Ionizing Radiation

All diagnostic imaging uses energy from across the electromagnetic spectrum, but CT, radiographs, nuclear medicine, mammography, and conventional angiography use ionizing radiation, which has enough energy to remove electrons from atoms, creating ions. The ions function as free radicals, causing damage to genetic material and biological tissues.

The developing fetus is particularly sensitive to ionizing radiation due to rapid mitotic rates. The risks are dose-dependent and vary based on the gestational age at exposure.

  • Preimplantation (0-2 weeks): During this period, radiation exposure is considered an "all or nothing" effect. High radiation doses can cause fetal demise, but survivors are generally unaffected.

  • Organogenesis (2-15 weeks): Due to the high mitotic rate, this is the most sensitive period for teratogenesis (prenatal toxicity causing structural or functional defects in the developing embryo/fetus). High radiation doses can lead to major congenital malformations, growth restriction, and central nervous system abnormalities. Notice in the CT below, the first trimester fetus is entirely contained within the pelvis; so, pelvic CTs are the most likely to affect the fetus.

  • Fetal Period (16 weeks to term): The risk for malformations is lower during this period, but there is continued risk for growth restriction, intellectual disability, and childhood cancer at very high doses. Notice in the CT below, the third trimester fetus extends beyond the pelvis.

Radiation doses from most diagnostic imaging studies are typically below the threshold for deterministic effects (minimum dose that triggers detectable biological effects, such as malformations). The threshold for deterministic effects is approximately 50-100 mGy. The estimated fetal dose from a single X-ray or non-abdominopelvic CT scan is below this threshold, but abdominopelvic imaging with CT significantly increases the dose, especially when the protocol calls for multiple passes, such as an exam with and without contrast or scans are repeated during the pregnancy.

Alternative Modalities that Do Not Use Ionizing Radiation

Ultrasound and magnetic resonance imaging use energy sources that are non-ionizing energy. Therefore, these 2 modalities are preferred for imaging during pregnancy.

Ultrasound

The cornerstone of obstetric imaging, ultrasound uses sound waves and carries no known risks to the fetus. It is the preferred imaging modality for most obstetric indications.

MRI

Magnetic Resonance Imaging uses strong magnetic fields and radio waves. It does not involve ionizing radiation. No known adverse effects on the fetus have been demonstrated. However, the use of MRI in the first trimester is generally reserved for compelling indications due to theoretical concerns and the evolving nature of fetal organogenesis.

Contrast Media in Pregnancy

Iodinated Contrast Media (ICM)

ICM is generally considered safe in pregnancy, though it does cross the placenta. The primary concern is potential transient fetal hypothyroidism, particularly with repeated administration of ICMs. If an ICM is necessary, a single dose is usually acceptable. Monitoring neonatal thyroid function is recommended after exposure to multiple doses.

Gadolinium-Based Contrast Agent (GBCA)

GBCAs cross the placenta, and gadolinium is retained in fetal tissues. Studies have shown a potential association with an increased risk of rheumatological, inflammatory, and dermatological conditions in children exposed in utero. Therefore, GBCAs are generally avoided in pregnancy unless essential and the benefit clearly outweighs the potential risks.

Management

Despite the risks associated with imaging during pregnancy, diagnostic imaging can be lifesaving for both the mother and the fetus.

  • Accurate diagnosis of acute conditions (e.g., appendicitis, pulmonary embolism, ectopic pregnancy) can prevent maternal morbidity and mortality.

  • Imaging can guide interventions, such as drain placement or surgical planning.

  • Ultrasound is essential for monitoring fetal growth, assessing anatomy, and diagnosing complications.

Considerations in Imaging Pregnant Patients

  • Assess Pregnancy Status: Always inquire about pregnancy in women of childbearing age before any imaging study. Unless a patient has had a hysterectomy, a pregnancy test should be performed, even if they state that they are not pregnant or cannot be pregnant.

  • Justification: Is imaging truly necessary? Can the diagnosis be made clinically or with an alternative study?

  • Consider the ALARA Principle: ALARA stands for "As Low As Reasonably Achievable." If an imaging modality using ionizing radiation is necessary, optimize the protocol to minimize the fetal dose. Shielding is no longer considered necessary.

  • Consider Alternatives

    • Ultrasound: First line for many conditions.

    • MRI without contrast: Excellent for soft tissue evaluation and can often replace CT for certain indications.

  • Contrast Media

    • ICM: Generally safe; consider a single dose if necessary. Monitor neonatal thyroid function after repeated doses.

    • GBCA: Avoid unless absolutely necessary; obtain informed consent from the mother, discussing the potential risks, benefits, and alternatives.

  • Informed Consent

    • The American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG) recommend that explicit, and often written, informed consent be obtained for any CT scan where the fetus is in the primary beam. This is because these scans carry a higher, though still very low, radiation exposure risk to the fetus compared to scans of other anatomic regions.

    • A physician should receive informed consent from a pregnant patient for a CT scan after a thorough discussion of the risks and benefits, and before the imaging procedure is performed. The timing and documentation requirements vary depending on the area of the body being scanned and the associated fetal radiation dose.

    • The referring physician, in consultation with a radiologist, is responsible for ensuring this process is followed.

  • Consult Radiology: When in doubt, consult with a radiologist to determine the safest and most effective imaging strategy.

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Case Presentation Restated

A 25-year-old pregnant patient presents with abdomen pain.

Questions

1. What are the risks associated with imaging during pregnancy?

2. What is the most appropriate initial diagnostic imaging modality of choice?

3. When is informed consent obtained before imaging a pregnant patient?

Answers:

1. Diagnostic imaging in a pregnant patient presents 2 primary risks, i.e. the potential effects of ionizing radiation and the safety of contrast agents. All diagnostic imaging uses energy from across the electromagnetic spectrum, but CT, radiographs, nuclear medicine, mammography, and conventional angiography uses ionizing radiation, which has energy high enough to remove electrons from atoms, creating ions. The ions function as free radicals, causing damage to genetic and biological tissues. ICMs are generally considered safe in pregnancy, though they do cross the placenta. GBCAs are generally avoided in pregnancy unless essential and the benefit clearly outweighs the potential risks.

2. If possible, consider ultrasound or MRI without contrast for initial diagnostic imaging needs.

3. The American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG) recommend that explicit, and often written, informed consent be obtained for any CT scan where the fetus is in the primary beam.

Additional Resources and References

  • Albakri AA, Alzahrani MM, Alghamdi SH. Medical Imaging in Pregnancy: Safety, Appropriate Utilization, and Alternative Modalities for Imaging Pregnant Patients. Cureus. 2024 Feb 17;16(2): e54346. doi: 10.7759/cureus.54346. PMID: 38500900; PMCID: PMC10945608.

  • American College of Obstetricians and Gynecologists (ACOG) – Informed Consent and Shared Decision Making in Obstetrics and Gynecology: ACOG Committee Opinion, Number 819. Obstet Gynecol. 2021 Feb 1;137(2):e34-e41. doi: 10.1097/AOG.0000000000004247. PMID: 33481530.

  • American College of Radiology (ACR) – Society of Pediatric Radiology (SPR) Practice Parameter for Imaging Pregnant or Potentially Pregnant Patients with Ionizing Radiation, 2023 Revision.

  • Begano D, Söderberg M, Bolejko A. To Use or Not Use Patient Shielding on Pregnant Women Undergoing Ct Pulmonary Angiography: A Phantom Study. Radiat Prot Dosimetry. 2020 Jul 24;189(4):458-465. doi: 10.1093/rpd/ncaa059. PMID: 32424428; PMCID: PMC7380303.

  • Bourgioti C, Konidari M, Gourtsoyianni S, Moulopoulos LA. Imaging during pregnancy: What the radiologist needs to know. Diagn Interv Imaging. 2021 Oct;102(10):593-603. doi: 10.1016/j.diii.2021.05.003. Epub 2021 May 28. PMID: 34059484.

  • Kwan ML, Miglioretti DL, Marlow EC, Aiello Bowles EJ, Weinmann S, Cheng SY, Deosaransingh KA, Chavan P, Moy LM, Bolch WE, Duncan JR, Greenlee RT, Kushi LH, Pole JD, Rahm AK, Stout NK, Smith-Bindman R; Radiation-Induced Cancers Study Team. Trends in Medical Imaging During Pregnancy in the United States and Ontario, Canada, 1996 to 2016. JAMA Netw Open. 2019 Jul 3;2(7):e197249. doi: 10.1001/jamanetworkopen.2019.7249. PMID: 31339541; PMCID: PMC6659354.

  • Lowe S. Diagnostic imaging in pregnancy: Making informed decisions. Obstetric Medicine. 2019 Sep;12(3):116-122. doi: 10.1177/1753495X19838658. Epub 2019 Apr 11. PMID: 31523267; PMCID: PMC6734637.

  • Tirada N, Dreizin D, Khati NJ, Akin EA, Zeman RK. Imaging Pregnant and Lactating Patients. RadioGraphics. 2015 Oct;35(6):1751-65. doi: 10.1148/rg.2015150031. PMID: 26466183.

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]]><![CDATA[Why I Created Applied Clinical Radiology]]>https://appliedclinicalradiology.substack.com/p/why-applied-clinical-radiologyhttps://appliedclinicalradiology.substack.com/p/why-applied-clinical-radiologyTue, 29 Jul 2025 12:26:26 GMTIn September 2023, one of my radiology technologists came to me with a requisition for a low-dose screening CT of the chest on a patient who was currently being treated for lung cancer. The order had been placed by a second-year oncology fellow, who explained to me that the patient was undergoing radiation therapy for his cancer and the fellow wanted to limit any “unnecessary” radiation. He did not understand the vast difference in radiation exposure of chest CTs compared to the therapeutic doses used by radiation oncologists.

Five days later, another radiology technologist came to me with a requisition for a high-resolution chest CT (HRCT) with the indication “Breast cancer staging.” The order had been placed by a third-year internal medicine resident. He explained to me that he thought that the higher resolution scan would give better delineation of the patient’s malignancy and any metastases that she may have. He did not understand what HRCT was and that it is narrowly tailored to assess interstitial lung disease.

Radiology does not receive much time in most medical school curricula. There’s so much that physicians must learn, and there’s only so many hours in a day and days in a year. So, it is not difficult for me to be sympathetic with the oncology fellows and internal medicine residents who are doing the best that they can with what they have been taught. If I had not pursued a career in radiology, I am sure I would have been in their shoes on one day or another. Have you been there? Keep reading!

Nonradiologists need an understanding of how radiology is applied in clinical practice, i.e. "A Radiology User's Manual for the Nonradiologist." In searching for textbooks and resources on "radiology for the nonradiologist," almost without exception, resources that are available cover content from the perspective of a radiologist, focusing on interpretation of images and imaging findings. These texts could be titled, "Radiology-lite" as they cover interpreting imaging from a very superficial perspective. For example, the texts may have a chapter titled, "How to Read a Chest X-ray," but they will not discuss how to read radiology reports. They cover anatomy and findings on a chest x-ray, but they provide little about the appropriateness of ordering the chest x-ray or safety concerns about imaging, and even less about the advanced modalities. The nonradiologist needs to know more than just “How to Read a Chest X-ray.”

If this resonates with you, you may be interested in future posts on Applied Clinical Radiology! Subscribe for free to receive new posts and support my work.

Physicians who do not pursue a career in radiology need to understand what diagnostic imaging does for them and more importantly for their patients. The nonradiologist needs to know how to select the appropriate exam to order to meet their patient’s needs, how to view an imaging exam in conjunction with the radiologist’s report, and how to follow-up on significant findings.

Nonradiologists need to understand the principles of diagnostic imaging, including the various modalities, such as radiographs (XR), fluoroscopy (FL), computed tomography (CT), magnetic resonance imaging (MRI), mammography (MG), nuclear medicine (NM), and positron emission tomography (PET). They need to understand what each modality offers…what each exam can do…and what it cannot do.

The nonradiologist needs to understand what to order and when to be able to maximize their patient’s health resources, achieving a diagnostic assessment in the most efficient, cost-effective way possible. During each step of developing and executing the patient's care plan, the nonradiologist needs to know what to do next and how imaging fits into that next step. Should a follow-up diagnostic imaging study be considered or is no additional imaging needed or appropriate? Should imaging results prompt an expert consultation with surgery, oncology, pulmonology, or another specialty?

Ordering an exam “just to see what we can see” is inappropriate use of the patient’s resources and time as well as a major reason why the healthcare system is backlogged with imaging requests. The use of imaging over the last three decades has placed stress on healthcare delivery in the United States. Overutilization of diagnostic imaging and inappropriate orders are the basis of the CMS requirement for clinical decision support mechanisms. Much of this is due to a lack of understanding of how the tools of diagnostic imaging can be effectively used in a patient care plan.

Nonradiologists need an understanding of patient safety concerns when considering a radiology exam. They need to be aware of the risks, benefits, and alternatives of each exam that they are considering. When an exam uses radiation (XR, CT, NM etc.), the ordering physician needs to understand the principles of radiation safety and mitigation, applying the ALARA (As Low As Reasonably Achievable) principle and consider resources such as the ACRs Appropriateness Criteria, Imaging Wisely, Choosing Wisely, or Image Gently. When considering an MRI, the ordering physician needs to consider the risks of magnetism on implanted devices, hardware, and other ferromagnetic objects within the patient as well as the length of time a MRI exam will take, i.e., can the patient lay supine for the time needed to obtain the MRI?

The nonradiologist needs to understand the perspective of the radiologist. Often, radiologists are presented with imaging exams where the indication and the exam don’t align, maybe a different exam should have been ordered, or the indication was inaccurate or incorrect. These exams can be seen as “unnecessary” and diminish the value of the radiologist’s time and energy, which is a major contributing factor to burnout in radiologists. When reporting these exams, the radiologist will frequently recommend a follow-up exam, which may have been the preferred exam for the indication.

To address these issues, I created a course for senior medical school students…part online modules and part in the department or radiology observing patients undergoing exams and procedures. I called it Applied Clinical Radiology. The content in this Substack is directly from or expanded from the content in the course. Sorry, you can’t come to visit the Department of Radiology to observe, but you can take advantage of the online content from the modules. Each post focuses on a specific topic to create an applicable approach for applying radiology in the clinical setting, hence the title Applied Clinical Radiology.

If this resonates with you, you may be interested in future posts on Applied Clinical Radiology! Subscribe for free to receive new posts and support my work.

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