Potential contribution of computer-aided detection to the sensitivity of screening mammography.

PURPOSE: To determine the false-negative rate in screening mammography, the capability of computer-aided detection (CAD) to identify these missed lesions, and whether or not CAD increases the radiologists' recall rate. MATERIALS AND METHODS: All available screening mammograms that led to the detection of biopsy-proved cancer (n = 1,083) and the most recent corresponding prior mammograms (n = 427) were collected from 13 facilities. Panels of radiologists evaluated the retrospectively visible prior mammograms by means of blinded review. All mammograms were analyzed by a CAD system that marks features associated with cancer. The recall rates of 14 radiologists were prospectively measured before and after installation of the CAD system. RESULTS: At retrospective review, 67% (286 of 427) of screening mammography-detected breast cancers were visible on the prior mammograms. At independent, blinded review by panels of radiologists, 27% (115 of 427) were interpreted as warranting recall on the basis of a statistical evaluation index; and the CAD system correctly marked 77% (89 of 115) of these cases. The original attending radiologists' sensitivity was 79% (427 of [427 + 115]). There was no statistically significant increase in the radiologists' recall rate when comparing the values before (8.3%) with those after (7.6%) installation of the CAD system. CONCLUSION: The original attending radiologists had a false-negative rate of 21% (115 of [427 + 115]). CAD prompting could have potentially helped reduce this false-negative rate by 77% (89 of 115) without an increase in the recall rate.

The promise of computer aided detection in digital mammography.

Computer-aided detection (CAD) is a new technology now being implemented in many clinics to reduce the false negative rate in mammography screening. A large clinical study has been completed which shows that a substantial false negative (miss) rate exists in screening mammography, a significant fraction of the missed cancers are not subtle, and CAD has high sensitivity to these missed cancers. Full field digital mammography is now coming on the scene, but has not yet been proven in clinical practice. The authors believe that full acceptance of the new digital technology depends not merely on demonstrations of 'substantial equivalence' to film-screen technology, but rather on more complete exploitation of the unique advantages of digital technology, and that CAD can play a key role. These advantages derive from CAD's ability to quickly (in near real-time) perform analytical computations on digital information that is not readily available to the radiologist until after the cost of film-processing has occurred.

Clinical importance of reinterpretation of body CT scans obtained elsewhere in patients referred for care at a tertiary cancer center.

PURPOSE: To determine the frequency and clinical importance of discordance between the initial interpretation of computed tomographic (CT) scans of the body and subsequent interpretations in patients with biopsy-proved cancer. MATERIALS AND METHODS: The initial and reinterpretation reports for 213 CT scans of the body submitted for official review were compared independently by two radiologists. Sixty-nine sets of reports were excluded because the reviewing radiologists and the outside radiologists had prior CT scans from differing dates to use for comparison. One set of reports was excluded because of lack of clinical follow-up. RESULTS: The interpretations were graded as "agree" in 90 patients (63%), "major disagreement" in 24 patients (17%), and "minor disagreement" in 29 patients (20%). A theoretic change in treatment could have occurred in nine of 53 cases of disagreement (17%). An actual change in treatment occurred in five of 53 cases of disagreement (9%). CONCLUSION: Discordant interpretations were frequent (53 of 143 cases [37%]), were often major (24 of 143 cases [17%]), and resulted in actual treatment changes in five of all 143 cases (3%). Reinterpretation of body CT scans can have a substantial effect on the clinical care of individual patients with proved malignancy.

Misrepresentation of publications by applicants for radiology fellowships: is it a problem?

OBJECTIVE: We performed this study to determine whether applicants to the body and breast/body imaging fellowship programs at our institution misrepresented their publications in their applications or curricula vitae, as has been reported recently regarding applicants for gastroenterology fellowships. We also wanted to alert program directors to this issue. MATERIALS AND METHODS: For each applicant in 1992-1995, every article cited on an application form or curriculum vitae as published or in press was cross-referenced with computer databases or the actual journals. RESULTS: Of 201 applicants, 87 (43%) listed at least one article citation (total citations, 261; mean number of citations, 3.0; maximum number of citations, 20). Of 261 citations, 39 (15%) could not be verified. Seven articles (listed by six applicants) did not appear in print 16-30 months after being listed as in press; six citations (by six applicants) put the applicant's name higher on the authorship list than was actually true; two articles (by two applicants) were not in the location cited or elsewhere; and 24 articles (by 14 applicants) were listed as appearing in journals that could not be found. The first three categories were judged as misrepresentations of publications; the fourth category was judged indeterminate for misrepresentation. CONCLUSION: A minimum of 16% (14/87) of applicants to the body and breast/body imaging fellowship programs at our institution who cited publications, or 7% of all 201 applicants in the time studied, appear to have misrepresented their publication record. Program directors should be aware of the possible means for prevention of this problem.

Non-Hodgkin lymphoma as a cause of intrahepatic periportal low attenuation on CT.

Two cases of non-Hodgkin lymphoma (NHL), one AIDS related, with hepatic involvement manifesting as infiltrating mass-like periportal intrahepatic low attenuation on CT are described. One case demonstrated mass effect with compression of adjacent bile ducts causing jaundice. NHL should be included in the differential diagnosis of mass-like periportal intrahepatic low attenuation lesions.

CT detection of retroperitoneal lymph node metastases in patients with clinical stage I testicular nonseminomatous germ cell cancer: assessment of size and distribution criteria.

OBJECTIVE: Patients with nonseminomatous germ cell cancer of the testis with no evidence of metastatic disease after orchiectomy may be managed with either retroperitoneal lymph node dissection or surveillance. The present retrospective study was undertaken to determine the accuracy of CT for revealing retroperitoneal lymph node metastases in patients with newly diagnosed clinical stage 1 testicular nonseminomatous germ cell cancer of the testis when smaller size criteria (smaller than 10 mm) are applied and to test the hypothesis that CT-revealed anterior retroperitoneal lymph nodes are more likely to correlate with metastases than are posterior lymph nodes. MATERIALS AND METHODS: Abdominal CT scans obtained before surgery in 70 patients were reviewed by three observers who were unaware of the results of retroperitoneal lymphadenectomy. The sizes and sites of all lymph nodes measuring larger than or equal to 4 mm were recorded. Each CT scan was judged as positive or negative for retroperitoneal metastasis on the basis of the size of the largest measured lymph node at the expected metastatic site. Diameters of 4, 6, 8, and 10 mm were successively applied to each case as the criteria for a positive scan. RESULTS: Using a criterion of 10 mm or larger for metastases, we calculated a sensitivity of 37% and a specificity of 100%; with a 4-mm criterion, the sensitivity was 93% and the specificity was 58%. Receiver operating characteristic curves comparing the accuracy of CT for revealing similar-sized lymph nodes located anterior or posterior to a line bisecting the aorta differed significantly (p = .04) when the same criteria were applied to lymph nodes in both regions. CONCLUSION: False-negative rates were decreased from 63% using a size criterion of 10 mm to as low as 7% using a size criterion of 4 mm, with a corresponding decrease in specificity. Lymph nodes measuring larger than or equal to 4 mm, especially those located anterior to the mid portion of the aorta, should raise a suspicion of metastases.

Voice recognition in radiology reporting.

OBJECTIVE: Recent advances in computer hardware and software technology have improved voice recognition systems used for radiology reporting. We describe and analyze this technology and some of its costs as well as the prospects for using voice recognition systems in the transcription of radiology reports. Factors to be considered in choosing a system include language model, speech flow, vocabulary size, and methods of acoustic modeling. CONCLUSION: Careful evaluation of individual radiology practice will permit proper introduction of voice recognition technology into mainstream clinical use. With this new technology, radiologists can use normal speech patterns to dictate while reviewing films. Also, this technology can use standard personal computers to reduce hardware costs to a level acceptable to radiology departments.

Non-Hodgkin lymphoma in skeletal muscle manifesting as homogeneous masses with CT attenuation similar to muscle.

Two cases are presented of masses in muscle due to non-Hodgkin lymphoma (NHL) that were homogeneous and isoattenuating to normal muscle on CT. In each case, the mass was clinically suspected of representing soft tissue sarcoma. However, the masses were relatively inapparent on CT, being visible predominantly as mass effect--an appearance unlike that of soft tissue sarcomas. It is important to be aware that NHL in muscle can be difficult to detect at CT, even with intravenous contrast enhancement; therefore, a clinically apparent mass should not be dismissed on the basis of an apparently unremarkable CT scan of the region. Such findings should suggest the diagnosis of NHL rather than sarcoma.

The cisterna chyli: a potential mimic of retrocrural lymphadenopathy on CT scans.

PURPOSE: To determine the normal appearance of the cisterna chyli and how it may mimic an enlarged retrocrural lymph node on computed tomographic (CT) images. MATERIALS AND METHODS: CT scans were reviewed in 18 patients (17 with cancer, one with benign disease) who had tubular retrocrural structures of attenuation near that of water. The location, diameter, length, CT attenuation, duration of finding, change in size, and the status of intercurrent malignancy were recorded. RESULTS: The cisterna chyli was variably located at T12-L1 (n=11), at T11-T12 (n=5), and at T-12 (n=2). The average length was 3 cm. The average CT attenuation was 12.5 HU. On serial scans in 14 patients, the average change in size was 2.2 mm despite progression or regression of malignant disease at other sites in 11 patients. CONCLUSION: The cisterna chyli can mimic the appearance of an enlarged retrocrural lymph node. Proper identification depends on its characteristic location, tubular configuration, attenuation closer to that of water than soft tissue, and lack of substantial change in size despite changes in disease at other sites.

Non-Hodgkin lymphoma: contribution of chest CT in the initial staging evaluation.

PURPOSE: To analyze incremental information derived from routinely obtained chest computed tomographic (CT) scans compared with chest radiographs in newly diagnosed non-Hodgkin lymphoma and the effect of this information on staging and therapy. MATERIALS AND METHODS: Abnormalities on chest radiographs and CT scans obtained at specific sites were prospectively identified in 181 consecutive patients with no previous treatment. When discrepant information was found, the effect on staging and treatment was determined. RESULTS: CT and chest radiographic findings were negative in 99 (55%) patients. CT findings were positive and chest radiograph findings were negative in 17 (9%). Both chest radiograph and CT findings were positive in 65 (36%) patients, 16 with identical sites of disease and 49 with more extensive intrathoracic disease at CT. Most stage changes occurred in the diffuse large cell histologic subtype. CONCLUSION: Although routine chest CT findings increased stage of disease in some patients, it had no effect on initial treatment of newly diagnosed non-Hodgkin lymphoma at this institution.

CT bone window photography in patients with cancer.

PURPOSE: To assess the utility of routinely photographing computed tomographic (CT) bone windows in patients with cancer. MATERIALS AND METHODS: The impression section of body CT reports were reviewed in 4,683 patients with cancer (2,240 female and 2,443 male patients, aged 2 months to 97 years [mean, 55 years]). RESULTS: The presence of definite or possible bone metastasis was mentioned in 523 (11.2%) patients. No prior radiologic examination was available in 165 patients. In the 358 patients who had undergone previous radiologic examinations, findings were positive in 271 and normal or indeterminate in 87. In 252 (5.4%) patients, CT with bone windows may have been needed for diagnosis of bone metastasis: 110 had extensive nonosseous metastases, 77 had no osseous metastasis, 19 had bone findings that were not followed up radiologically, and 46 had bone lesions that were new findings. These new lesions were visible on scans photographed at soft-tissue windows in 45 (97.8%) patients. CONCLUSION: Routine photography of CT bone windows is not necessary in patients with cancer.

Characterization of reactive versus tumor-bearing lymph nodes with interstitial magnetic resonance lymphography in an animal model.

RATIONALE AND OBJECTIVES: To determine if magnetic resonance lymphography performed with subcutaneously administered AMI-227, a nanoparticulate iron oxide contrast agent, can distinguish reactive from tumor-bearing lymph nodes. MATERIALS AND METHODS: Mature male Copenhagen rats were inoculated with cell suspensions of R3327-MAT-LyLu rat prostate carcinoma (n = 21) or Freund's complete adjuvant (n = 15) in the left footpad to generate ipsilateral popliteal lymph node metastases or lymphadenitis. At 12 to 14 days after inoculation, T1-and T2-weighted magnetic resonance images of bilateral popliteal areas were obtained before and 24 hours after subcutaneous administration of AMI-227. Contrast-to-noise ratios were calculated in precontrast and postcontrast images. Bilateral popliteal nodes were excised for pathologic assessment. RESULTS: AMI-227 resulted in decreased contrast-to-noise ratios in reactive (T1-W = -7.01 +/- 1.13, T2- W = -31.64 +/- 5.35) and normal (T1 - W = -13.56 +/- 1.97, T2 - W = -21.62 +/- 2.51) nodes. Contrast-to-noise ratios were unchanged (T1 - W = -0.22 +/- 1.71, T2 - W = -2.20 +/- 4.19) in tumor-containing nodes. These differences in contrast-to-noise ratio changes between tumor-bearing versus nontumor-bearing nodes were statistically significant (P < 0.05). Histologic analysis showed similar distribution of AMI-227 within normal and reactive nodes, but not in tumor-bearing nodes. CONCLUSIONS: Differences in AMI-227-uptake between tumor- and nontumor-bearing nodes detected with magnetic resonance imaging are helpful for distinguishing the two entities.

AMI-227-enhanced MR lymphography: usefulness for differentiating reactive from tumor-bearing lymph nodes.

PURPOSE: To determine the value of magnetic resonance (MR) lymphography enhanced with AMI-227, a superparamagnetic reticuloendothelial-system-specific contrast agent, to distinguish normal and reactive from tumor-bearing lymph nodes. MATERIALS AND METHODS: Mature male Copenhagen rats were inoculated with cell suspensions of R3327-MATLyLu rat prostate carcinoma (n = 16) or Complete Freund Adjuvant (n = 15) to generate ipsilateral popliteal lymph node metastases or lymphadenitis. At 12-14 days after inoculation, T1- and T2-weighted MR images of bilateral popliteal areas were obtained before and 24 hours after administration of AMI-227 (dose, 30 mumol Fe/kg). The contralateral popliteal nodes served as controls. Contrast-to-noise ratios (C/Ns) between the nodes and adjacent muscle were calculated in pre- and postcontrast images. Subsequently, bilateral popliteal nodes were excised. RESULTS: AMI-227 resulted in decreased C/N in reactive nodes (T1-weighted, -186% +/- 90% [standard deviation]; T2-weighted, -205% +/- 96%) and normal nodes (n = 7) (T1-weighted, -306% +/- 82; T2-weighted, -350% +/- 96). C/N remained unchanged or increased (T1-weighted, 88% +/- 92; T2-weighted, 306% +/- 256) (P < .05). CONCLUSION: Differences in AMI-227 uptake at MR imaging may help differentiate tumor-bearing from nontumor-bearing nodes.

Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings?

OBJECTIVE: High-resolution CT findings in patients with asbestosis include subpleural curvilinear densities, subpleural density in dependent portions of the lung, parenchymal bands, thickened septal lines, and honeycomb lung. Our objective was to examine the prevalence of these CT findings in a random group of patients scanned for a variety of clinical reasons not specifically related to occupational exposure. MATERIALS AND METHODS: One hundred sixty-eight CT studies of the thorax were performed at six levels in 168 patients examined for a variety of clinical indications. The scans were evaluated by two radiologists for the presence of subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, thickened septal lines, and honeycomb lung. RESULTS: CT scans of 11 patients showed pleural plaques suggesting previous exposure to asbestos. Among the 157 studies showing no evidence of pleural plaques, CT scans showed subpleural curvilinear densities in dependent areas in 32 (20%); subpleural curvilinear densities in nondependent areas in 19 (12%); parenchymal bands in 47 (30%); thickened septal lines in dependent areas in 93 (59%), and septal lines in nondependent areas in 67 (43%); subpleural density in dependent areas in 66 (42%); and honeycomb lung in five (3%). CONCLUSION: Subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, and thickened septal lines occur as isolated and as combined CT findings in patients with a variety of underlying diseases or conditions unrelated to asbestosis and by themselves are nonspecific findings. Their occurrence, even in patients with CT evidence of pleural plaques, does not necessarily indicate the presence of asbestosis.

Low-density supradiaphragmatic band artifact on advanced multiple-beam equalization radiography of the chest.

RATIONALE AND OBJECTIVES: A low-density dark band artifact was found above the diaphragm on advanced multiple-beam equalization radiography (AMBER) of the chest and was evaluated. METHODS: Fifty consecutive chest radiographs were evaluated for the presence of the artifact. AMBER radiographs of a phantom were scanned with a microdensitometer. RESULTS AND CONCLUSION: The presence of the artifact is confirmed on the patient chest radiographs (present in 84% on posteroanterior view; 94% on lateral view) and on the phantom images. The artifact was probably caused by a delayed system response to scanning across a sharp boundary.

Diagnostic imaging studies in patients with newly diagnosed Hodgkin's disease.

A variety of diagnostic imaging studies are used to evaluate patients with newly diagnosed Hodgkin's disease which provide important information to determine stage and guide patient management. The following will review the current status of diagnostic imaging studies as applied to evaluation of the thorax, abdomen and pelvis, with comment on areas under investigation.

Preaortic iliac venous confluence ("marsupial cava"): a rare anomaly of the inferior vena cava.

A patient was shown by computed tomography (CT) to have a rare developmental anomaly of the inferior vena cava (IVC), in which the iliac venous confluence is located anterior (rather than posterior) to the right common iliac artery. Recognition of the anomaly is important prior to surgical intervention in that area, as well as to prevent misinterpretation of the anomaly as representing adenopathy.