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A screening examination is applied to a particular population (ie, those who meet specific age, demographic, or risk criteria) in an effort to identify the presence of an undiagnosed disease in patients without signs or symptoms. In general, screening tests are performed on individuals who are in good health with respect to the disease that is being screened (ie, they have not yet been diagnosed with that disease).

A diagnostic examination is performed in a patient who has signs or symptoms of a disease state. The diagnostic examination is performed to establish a diagnosis that may explain the patient’s signs or symptoms.

Screening and diagnostic examinations are compared to reference standards (or their surrogates) that definitively determine the presence or absence of the disease. An example of a common reference standard is pathologic analysis of a detected malignancy.

[http://emedicine.medscape.com/article/773832-overview]

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For a screening test to be effective, certain criteria must be met. A list of 10 criteria for effective screening examinations are often referred to as Wilson’s Criteria and were published by the World Health Organization [WHO] in 1968. The criteria include:• The disease being screened should be an important health issue• The disease should be treatable• Facilities for treatment and diagnosis should be established and available• The disease should have a latent phase [to allow time for diagnosis and treatment]• There should be a practical test for the disease

• The test should be accepted by the population being screened• The disease and its typical course should be relatively well understood• There should be consensus of who to treat• The cost of detecting and treating a new case of the disease should be balanced against its natural course without screening• Screening should be a continuous process

[http://apps.who.int/iris/bitstream/10665/37650/1/WHO_PHP_34.pdf]

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• Breast [mammography]• Lung [chest CT]• Colon [optical colonoscopy]• Cervical cancer [pap]

Prostate cancer represents a somewhat different situation: Until recently, the PSA test was the gold standard as part of physical examinations for men, especially in those older than 50 years of age. As of October 2011, however, the U.S. Preventive Services Task Force (USPSTF) no longer recommends that men older than 50 years routinely receive PSA testing.[3] This is because there is no consensus that screening for prostate cancer saves lives, and also because treatment often leads to complications (e.g., impotence and incontinence). As a result, the decision to undergo prostate cancer screening now involves weighing the potential risks and benefits of screening. An active-surveillance approach to deciding when and if treatment is appropriate may also be considered if the cancer is found to be progressing. (from http://www.medscape.com/viewarticle/766698 accessed Dec 4, 2015)

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• Mammography is the only method of screening for breast cancer shown to decrease mortality.

[https://acsearch.acr.org/docs/70910/Narrative/]

Note, may want to discuss briefly that while MRI and US have been used for high risk screening in selective groups as an adjunct to mammography (e.g. BRCA), and have been shown to identify more cancers, no studies have been done that show a decrease in mortality.

Ask them why these have not been done (as randomization, long follow up, very large numbers and $$ needed).

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• Microcalcifications• Tissue asymmetry• Irregular, spiculated mass

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• CC view of the right breast shows a new opacity in study 2 years later. See if they can see it

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• MLO of the right breast shows a new opacity in study 2 years later. See if they can see it

Lung cancer screening is typically performed with low-dose CT which is approximately 1/7th of the dose of a standard chest CT. While the images appear to be a bit ‘noisy’, they are sufficient for detecting lung nodules. A small nodule [like the one that will be shown in the next case example] would not likely be detected on routine chest radiography.

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A 67 year-old female was enrolled in a lung cancer screening program due to her significant past and current smoking history.• Image 1: low dose CT image shows a spiculated nodule in the left upper lobe consistent with primary lung malignancy. Pathology showed adenocarcinoma.• Image 2: A CT from 12 months prior shows no nodule.

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Colorectal screening tools can be generally separated into 2 categories:• Those that screen for polyps (potentially pre-cancerous

lesions) and cancer [fecal occult blood testing (FOBT), fecal immunochemical test, stool DNA test]

• Those that screen for cancer only [colonoscopy, flexible sigmoidoscopy, double-contrast barium enema, CT colonography]

• Optical colonoscopy is currently considered to be the most sensitive and specific for detecting colorectal polyps and cancers.

• CT colonography [see ACR Appropriateness Criteria on next slide]


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• Optical colonoscopy is currently considered to be the most sensitive and specific for detecting colorectal polyps and cancers.

• CT colonography [see ACR Appropriateness Criteria narrative for more detail on this modality’s favorable performance in terms of sensitivity, specificity, complication rate, costs, etc]

(Consider to add explicit explanation that ACR AC is for Radiological imaging, and does NOT include other means of evaluation, like lab tests, or other types of diagnostic testing (like optical colonoscopy) and that is why optical colonoscopy does NOT appear in this document, though optical colonoscopy is the most sensitive and specific for detecting colorectal polyps and cancers.)

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• The patient drinks a preparatory liquid that cleanses the colon during the day preceding the examination.

• A plastic catheter is inserted into the rectum and barium contrast and air are insufflated into the colon lumen to achieve adequate distension. Fluoroscopic images are obtained with the patient in multiple positions.

• Patients who are immobile, frail, prone to dehydration with the preparation may not be suitable for a double contrast barium enema

• Filling defects within the lumen of the colon• Polyps can be either sessile [appearing as broad-based,

semicircular filling defects] or pedunculated [appearing as elongated, ovoid filling defects due to being on a long stalk]

Q: What type of study is this? A: Double contrast Barium Enema (aka air-contrast BE).Q: How do you choose whether to do Double contrast Barium Enema (aka air-contrast BE) versus single contrast BE? A: Generally, Air contrast is preferred, if the patient is able to complete the preparation before the exam (Go-Lytely to cleanse the colon) and is able to cooperate with Air contrast BE exam requirements to retain the enema and move as needed for the imaging. For patients who cannot, the single contrast enema may be a better choice, but single contrast enemas are less sensitive and specific in diagnosis compared to air contrast enemas for detection of polyps and cancer.Q: What is the finding? A: A small sessile polyp arising from the lateral wall of the descending colon. The polyp projects into the lumen of the colon and is outlined by barium contrast and air; some authors have described this as the ‘bowler’s hat’ appearance. In contrast, pedunculated polyps (not shown in this example) appear as more elongated or linear filling defects due their long stalks.

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• Filling defect within the lumen of the colon• Irregular mass that narrows the colonic lumen (ie, ‘apple core’

lesion)• Soft tissue shouldering (bunching of colonic tissue adjacent to

the mass resulting in a shelf-like or shoulder appearance)• Colonic obstruction

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Q: What type of study is this? A: Single contrast Barium Enema.Q: What do you think of the image? Normal or Abnormal? A: AbnormalQ: What is the finding? A: Circumferential mass lesion narrows colonic lumen and represents colorectal carcinoma in descending colon (classic “apple core” configuration lesion with luminal stricture and ‘shouldering’). No findings of obstruction.

• The initial steps of a CT colonography are similar to a barium enema. The patient drinks a preparatory liquid that cleanses the colon during the day preceding the examination. In addition, the patient ingests barium, which incorporates into residual fecal material (making it appear very dense on CT) and an iodinated contrast drink (iohexol or ditrizoic acid) to opacify residual liquid within the colon (also making it dense on CT). This process of “tagging” the fecal material and liquid is helpful in differentiating polyps from retained fecal material.

• At the time of the examination, a plastic catheter is inserted into the rectum and cabon dioxide is insufflated into the colon lumen to achieve adequate distension. CT imaging of the abdomen and pelvis is then performed in the supine and prone positions. 3-dimensional reformatting is performed to view the colon from inside the lumen.

• Irregular mass that narrows the colonic lumen (ie, ‘apple core’ lesion)

• Soft tissue shouldering (bunching of colonic tissue adjacent to the mass resulting in a shelf-like or shoulder appearance)

• Colonic obstruction• CT colonography also allows the radiologist to see the entire

colonic wall (not just changes affecting the mucosal surface of the lumen) and the extra-colonic tissues (ie, the pericolonic fat, lymph nodes, liver etc).

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Patient presents for screening CT colonography. A 9 mm sessile polyp is found in the sigmoid colon, on a fold. Endoluminal reconstruction image (next image to the right), attenuation-tool demonstrates the polyp is soft-tissue attenuation (red) with a small coating of contrast (white), and the blue arrow points to the polyp on the 2D CT. The patient went on to same-day optical colonoscopy for polypectomy (bottom image) and the pathology was a tubular adenoma.

Note: This discussion requires the student to apply a specific situation (ie, colorectal cancer screening) to some of the general principles of screening:

Q: How does screening for colon cancer fit the generalized model we discussed earlier for use of screening?• Colorectal cancer is an important medical problem – it is the 3rd overall leading cause of cancer deaths in the U.S. An average-risk individual has an approximately 5% lifetime risk of developing colorectal cancer.• Colorectal cancer is very treatable - detecting the disease when it is localized has long been associated with an excellent 5-year survival rate of approximately 80%.• The natural history of colorectal cancer is pretty well understood - evidence has accumulated to support the concept that almost all colorectal cancers develop from benign adenomas. The prevalence of adenomas in the general population is 30%–50% and increases with age. Most adenomas are diminutive (≤5 mm) or small (6–9 mm) in size.• Colorectal cancer has a long latency period – the transformation process is slow, requiring an average of 10 years.


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• PET-CT – this is a ‘fusion image’ during which the metabolic activity from the PET (positron emission tomography) is overlayed upon the anatomic data from the CT examination. Some organs, such as the liver, appear to be slightly yellow since their baseline metabolic activity is higher than other organs (such as the spleen).

The high cost of applying PET-CT to a large population make it impractical as an effective screening examination. Additionally, not all cancer types have sufficient metabolic activity to be detected by PET (several malignancies are ‘non-FDG avid’).

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PET-CT is an effective tool for tumor staging. In this case, the patient had newly diagnosed colon cancer and was found to have 3 low density liver lesions during staging CT. The PET-CT showed that only 1 of the lesions (shown as the ‘hot spot’ in the posterior segment of the right lobe) had increased metabolic activity. This examination enabled lesion selection for biopsy and facilitated the patient’s tumor staging.

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There are many clinical scenarios that may suggest malignancy. Some common examples include:• Unintended weight loss• Palpable mass or adenopathy• Massive ascites• Painless jaundice

Overall, the most common sites are:• lung• liver• bone[http://www.cancer.gov/about-cancer/what-is-cancer/metastatic-fact-sheet]

However, the location of metastases also depends on the type of primary cancer. See the table on the following slide.

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Here are 5 common malignancies and their most common sites of metastasis.

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• New onset seizure in adult• Mental status changes (ie, personality/mood changes, altered

levels of consciousness)• Ataxia• Headache

According to ACR Appropriateness Criteria, contrast-enhanced MRI is the most highly rated [see next slide]. However, CT may be considered to be the imaging study of choice per the comment in the ACR document [see first comment in following table].

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According to ACR Appropriateness Criteria, contrast-enhanced MRI is the most highly rated [see next slide]. However, CT may be considered to be the imaging study of choice per the comment in the ACR document [see first comment in following table].

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• Multiple lesions• Vasogenic edema (preferentially affects white matter

surrounding a lesion, with relative sparing of gray matter. Typical of primary tumors, metastases, and infections)

• Mass effect [herniation in advanced cases]• Intraparenchymal hemorrhage in some cases [potentially from

melanoma, renal cell carcinoma, others]• Osseous lesions [lytic and blastic]• Post-contrast CT: multiple enhancing lesions, most commonly

at grey-white junction

A 54 year-old female with a 30 pack-year smoking history presents with gradual worsening of headache and then new onset seizure.Q: What do you see here? A: Non-contrast head CT images shows several areas of vasogenic edema within both hemispheres.

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Q: What has been done ? A: This is a CT done after injection of intravenous contrast material.Q: What are the findings? A: Numerous enhancing lesions are apparent within both cerebral hemispheres due to metastatic disease from lung cancer.

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According to ACR Appropriateness Criteria, radiography or CT are the preferred modalities.• It is generally accepted that CXR, with posteroanterior and lateral views, should be the initial imaging evaluation for patients who have no known or suspected thoracic metastatic disease.• If chest radiography demonstrates obvious multiple pulmonary nodules, further imaging beyond follow-up CXR may not be indicated, unless a biopsy is planned or unless precise quantification of the disease is required (This is useful, because it can be a STOP point for work up).• For melanoma and testicular cancers, radiography is given a higher rating, whereas CT and radiography are rated equally for most of the other cancer types.

• [https://acsearch.acr.org/docs/69454/Narrative/]

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• Multiple lung parenchymal nodules/masses• Abnormal mediastinal contours [adenopathy]• Bony lesions

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• Compared with chest radiography, CT is much more sensitive for detecting pulmonary nodules because of its spatial resolution and lack of superimposition.

• Other abnormalities, such as lymphadenopathy, pleural involvement, chest wall lesions, endobronchial lesions, intravascular pulmonary involvement, or incidental findings in the upper abdomen (such as adrenal lesions), can also be revealed or better demonstrated with CT.

• If chest CT is performed alone [ie, without concurrent CT of the abdomen and pelvis], intravenous contrast material is not necessary, although it may be helpful in some situations when evaluating the mediastinum for adenopathy.


Get them to see if they can see the spine signA 55 year-old female presents for evaluation of cough. The PA and lateral chest radiographs are abnormal due to the positive ‘spine sign’ [RLL mass that overlies the thoracic spine on the lateral view results in abnormal density]. The patient was thought to have pneumonia and begun on antibiotics.

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Here are side by side comparison views of the radiographs performed at presentation and at follow up.Follow-up chest radiography performed after 2 weeks of antibiotic treatment What do they see?No change in opacity in the RLL.

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Here are side by side comparison views of the radiographs performed at presentation and at follow up. What do you notice?

There is a large, heterogeneous mass in the right lower lobe, located adjacent to the lower thoracic spine. This mass caused the ‘spine sign’ on the prior chest radiograph and is due to a primary lung cancer. (The astute student may point out that there is a pericardial effusion. If this comes up in discussion, facilitator may want to mention that the CT was done at some delay after the 2nd CXR. If this effusion enters the discussion, might be good to ask learners what might be the cause. In the setting of cancer, it can be a malignant effusion).

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The size of the primary lung tumor and the presence of mediastinal and right hilar nodal metastases are critical in the staging of this patient.How might PET-CT facilitate diagnosis and staging in this patient?• Since the PET-CT provides both structural [CT portion] and metabolic [PET portion] information, it can be helpful for selecting a target for biopsy. The top row shows only CT images while the bottom row shows the fused PET-CT images. The bright yellow areas indicate increased metabolism within the malignant lung tumor and within the metastatic nodes. Viable tumor cells are more likely to be recovered from biopsy of a metabolically active lesion compared to a non-metabolically active lesion.

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According to ACR Appropriateness Criteria, contrast-enhanced CT and MRI are preferred

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According to the ACR Appropriate Criteria, ‘CT is particularly suited for evaluating metastatic disease, because the liver and potential extrahepatic sites of tumor spread can be evaluated during the same examination’.• A contrast-enhanced CT of the chest, abdomen, and pelvis can be performed in approximately 2 minutes.• An MRI of the same body parts would take much longer (approximately 30-60 minutes).• The longer examination time of MRI may lead to more artifacts from breathing and patient motion.• CT typically has a lower cost than MRI.

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Typical appearance is multiple, round, low density masses within the hepatic parenchyma. Metastases are more likely to be low density and homogeneous when small (<2cm) but can be heterogeneous (due to necrosis and hemorrhage) as they become larger.

49 year-old male with metastatic colon cancer to liver. There are 4 hypoattenuating or low density lesions in the liver; the lesions show low level enhancement, but less so compared to the adjacent normal liver parenchyma. This is the typical appearance of metastatic disease in the liver on CT.

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Treatable with local therapies

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Q: How does the treatment approach differ in a patient with a solitary liver metastasis vs the approach in a patient with numerous diffuse metastases? A: There are more options for effective treatment in the patient with a solitary metastasis, in general.

This solitary liver metastasis in a patient with colorectal carcinoma was resected.

Skeletal metastases may be blastic (ie, bone forming) or lytic (ie, bone destroying). Some cancers (such as prostate and breast) are associated with blastic metastases while others (such as lung and renal cell carcinoma) are associated with lytic metastases. Additionally, some tumors result in a mixed pattern of skeletal metastases. In a patient with prostate cancer, skeletal metastases can be detected with radiography, CT, MRI, or bone scan.

Slide 53

Here are examples of imaging examinations from patients with prostate cancer.What do you see in the first image? Blastic metastases throughout the lumbar spine on an xray.What do you see in the second image? Blastic metastases in the sternum and spine on a sagittal CT.

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A bone scan is a functional imaging examination. The patient is injected with a radioactive tracer that is attached to a molecule that binds to bone. There is more uptake of the radiotracer at sites of active bone formation, so the radiotracer is taken up more readily by a metastasis compared to normal bone. Therefore, a bone scan is a very sensitive examination for detection of skeletal metastases due to prostate cancer; a bone scan can detect skeletal metastases before they are apparent on radiography or CT.

Here is an example of a bone scan (anterior & posterior images) from a patient with metastatic cancer.What do you see in the images? Numerous sites of increased skeletal uptake consistent with diffuse metastases.How would the results of this scan affect the treatment plan of a patient who was just diagnosed with prostate cancer?The patient would not be a surgical candidate but could receive systemic therapy.

Slide 56

A cancer’s stage indicates its severity. Staging is based on the tumor’s size and extent [ie, degree of spread]. Proper staging is important for many reasons and helps to determine the:• Optimal treatment plan• Prognosis• Suitability for clinical trials• Lexicon used in research

[http://www.cancer.gov/about-cancer/diagnosis-staging/staging/staging-fact-sheet]

Slide 57

In addition to imaging examinations, the following play a role in staging: physical examination, laboratory tests, pathology analysis, surgical reports. It is important to note that a tumor’s stage that was assigned after interpretation of an imaging study may be changed when all of these other factors are taken into account.


While there are several types of cancer staging systems, the common elements in most staging systems include:• Primary tumor site and cell type• Number of tumors• Tumor size and extent• Involvement of regional and distant lymph nodes• Tumor grade [ie, degree of differentiation/aggression]


Slide 59

While there are several types of cancer staging systems, the TNM system is one of the most widely used systems and has been accepted by the International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC). The TNM system has 3 basic components:• T [primary tumor]• N [regional lymph nodes]• M [distant metastasis]

See next slide for graphical depiction[http://www.cancer.gov/about-cancer/diagnosis-staging/staging/staging-fact-sheet]

Slide 60

Note: While most cancers are staged by the TNM system, not all of them are. For example, cancers of the brain and spinal cord are notable exceptions. Also, the Ann Arbor staging classification is commonly used to stage lymphomas while FIGO (International Federation of Gynecology and Obstetrics) is used for cancers of the female genitourinary tract. Finally, leukemias do not have a well defined staging system.

Imaging examinations provide information for the TNM staging criteria. For example, CT of the chest, abdomen, and pelvis can provide accurate information regarding a primary tumor’s size/extent, the presence or absence of abnormal appearing regional lymph nodes, and the presence of absence of distant metastasis. It should be noted that CT will detect adenopathy if the lymph nodes have abnormal size, number, or architecture, but tumor cells may still be present in otherwise normal appearing lymph nodes.Additionally, it should be noted that several national societies (such as the American Cancer Society) have issued recommendations for staging examinations for specific types of tumors.

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On the first CT image, there is a large, spiculated mass in the left upper lobe that invades the mediastinum and extends to the pleura. The finding that makes this a stage IV lung cancer is the large, heterogeneous metastasis in right adrenal gland.

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Treatment response has been historically assessed by changes in tumor size during follow-up contrast-enhanced CT or MRI. Tumor size can be assessed by measuring diameters or volumes. There are several sets of established criteria for evaluating tumor response based on size; one of the most commonly used is RECIST [Response Evaluation Criteria in Solid Tumors], which was established in 2000 by an international collaboration between numerous organizations. Currently, the majority of clinical trials evaluating cancer treatments for response of solid malignancies use RECIST.

For some solid malignancies, changes in tumor size do not necessarily reflect tumor response. In some tumors, size can actually increase due to hemorrhage, necrosis, or myxoid degeneration. An example is gastrointestinal stromal tumors being treated with newer molecular targeted therapies. During treatment, decrease in tumor size is usually minimal during the early stages, but there are significant changes in tumor density, nodularity, and enhancement. Therefore, additional response criteria have been proposed.What are some other imaging findings that can be used to assess a tumor’s response to chemotherapy? Tumor attenuation [density] and metabolic activity [as measured by PET] as measures of treatment response; these factors are part of the Choi criteria which accounts for factors other than size to evaluate tumor response. [http://pubs.rsna.org/doi/pdf/10.1148/rg.335125214]

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What has happened between the baseline CT and the follow-up scan performed 4 weeks later? Rapid progression of disease with development of multiple liver mets, ascites, carcinomatosis over the course of 4 weeks.

What are the important imaging findings following chemotherapy? Response following 8 cycles of chemotherapy with significant decrease in liver tumor burden and near-complete resolution of ascites and carcinomatosis.

Slide 66

The purpose of a tumor board is to enable a multi-disciplinary review and discussion of a patient’s cancer diagnosis so that the treatment plan is optimized and agreed upon by the group. Tumor boards are collaborative meetings during which various specialists exchange ideas to improve patient care. Specialists discuss the patient’s care in the context of established practice guidelines and determine if a patient may meet criteria for a clinical trial in some cases.

• Medical oncologist• Surgical oncologist• Radiation oncologist• Radiologist [diagnostic and interventional]• Pathologist• Medical specialists [gastroenterology, pulmonologist,

cardiologist, nephrologist]• Oncology nurses and care coordinators• Research trial coordinators

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• Direct patient interfacing [informing and counseling patients diagnosed with breast cancer during mammography/breast ultrasound]

• Consultant [frequent verbal interactions with medical, surgical, and radiation oncologists regarding appropriateness of imaging examinations]

• Diagnostician [interpretation of mammography, US, CT, MR, PET-CT, bone scans, radiography]

• Interventionalist [biopsy, chemoembolization, ablations, post-operative drainage, fiducial markers for radiation]

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