American Journal of Roentgenology

OBJECTIVE. This article measures the workload of radiologists in the United States in 1998-1999, its variation by practice characteristics, and changes since 1995-1996.

MATERIALS AND METHODS. Data on procedures performed were collected from the American College of Radiology's 1999 Survey of Practices, and responses were weighted to make them representative of all radiologists in the United States. Workload measured as number of procedures per full-time equivalent diagnostic radiologist was tabulated by practice type, size, setting, and location and compared with corresponding survey results from 1995-1996. The independent effect of these factors on workload was measured using regression analysis. Changes in procedure complexity were calculated in terms of relative value units (RVUs) per procedure using Medicare files.

RESULTS. In 1998-1999, the average workload per full-time equivalent diagnostic radiologist had increased 8.5% since 1995-1996 to 12,800 (standard error = 200) procedures annually, with substantial variation by group type. For example, the average workload was 9400 procedures in academic groups and 13,600 in nonacademic private radiology practices. Even in relatively homogeneous categories of practices, radiologists at the 75th percentile of workload were typically performing at least 50% more procedures than radiologists at the 25th percentile. Average RVUs per Medicare procedure increased by 4% between 1995 and 1998, mainly because of an increase in the share of more complex techniques such as MR imaging and CT in the procedure mix.

CONCLUSION. The workload per radiologist measured in procedures and RVUs increased substantially between 1995-1996 and 1998-1999. Because much variation remains unexplained, averages or medians should not be used as norms.

OBJECTIVE. The purpose of our study was to analyze the differences in clinical outcomes of diagnostic and screening mammography depending on whether comparison is made with previous examinations.

MATERIALS AND METHODS. We analyzed 48,281 consecutive mammography examinations for which previous mammography (9825 diagnostic, 38,456 screening) had been performed between 1997 and 2001, collecting data on demographics, whether comparison actually was made with previous examinations, abnormal findings (recall for screening mammography or biopsy recommendation for diagnostic mammography), biopsy yield of cancer, cancer detection rate, size of invasive cancers, axillary nodal status, and cancer stage.

RESULTS. Comparison with previous examinations in the incidence screening setting decreases the recall rate from 4.9% to 3.8% (p < 0.0001) but does not significantly affect the biopsy yield (40-44%, p = 0.56) or the cancer detection rate (5.5-5.2/1000, p = 0.87). In the diagnostic setting, comparison with previous examinations increases the biopsy-recommended rate from 4.3% to 9.4% (p < 0.0001), the biopsy yield from 38% to 51% (p = 0.12), and the overall cancer detection rate from 11/1000 to 39/1000 (p < 0.0001). Comparison with previous examinations is not associated with a significant difference in mean tumor size. However, it is associated with a significant decrease in the frequency of axillary node metastasis and the cancer stage for screening mammography, but not for diagnostic mammography.

CONCLUSION. For screening mammography, comparison with previous examinations significantly decreases false-positive but not true-positive findings and permits detection of cancers at an earlier stage. For diagnostic mammography, comparison with previous examinations increases true-positive findings.

OBJECTIVE. This study was conducted to evaluate the outcome of cases of radial scar diagnosed by percutaneous core needle biopsy.

MATERIALS AND METHODS. Of 198 nonpalpable lesions diagnosed with radial scars found at core needle biopsy, 157 lesions constituting the study group had undergone surgical excision (n = 102) or mammographic surveillance after biopsy for at least 24 months (median, 38 months; n = 55). Mammographic lesion type, lesion size, biopsy guidance method, biopsy device, number of specimens per lesion, and presence of atypical hyperplasia at percutaneous biopsy were retrospectively analyzed. Results were compared with histologic findings at surgery or mammographic findings during surveillance.

RESULTS. Carcinoma was found at excision in 28% (8/29) of lesions with associated atypical hyperplasia at percutaneous biopsy and 4% (5/128) of lesions without associated atypia (p < 0.0001). In the latter group, carcinoma was found at excision in 3% (2/60) of masses, 8% (3/40) of architectural distortions, and 0% (0/28) of microcalcification lesions. Malignancy was missed in 9% (5/58) of lesions biopsied with a spring-loaded device and in 0% (0/70) of lesions biopsied with a directional vacuum-assisted device (p = 0.01); and in 8% (5/60) of lesions sampled with less than 12 specimens per lesion and 0% (0/68) sampled with 12 or more specimens (p = 0.015). Lesion type, maximal lesion diameter, and type of imaging guidance (stereotactic or sonographic) were not significant factors in determining the presence of malignancy.

CONCLUSION. Diagnosis of radial scar based on core needle biopsy is likely to be reliable when there is no associated atypical hyperplasia at percutaneous biopsy, when the biopsy includes at least 12 specimens, and when mammographic findings are reconciled with histologic findings. When the lesion diagnosed by core needle biopsy as radial scar does not meet these criteria, excisional biopsy is indicated.

OBJECTIVE. Our objective was to assess the incidence of papillary lesions of the breast diagnosed at imaging-guided core needle biopsy and the need for surgical excision after a benign diagnosis.

MATERIALS AND METHODS. This retrospective study included 1374 patients with consecutive suspicious breast lesions that underwent either mammography or sonographically guided large-core needle breast biopsy. Fifty-seven lesions (4%) were classified as papillary lesions. Eleven of the 57 cases were lost to follow-up (n = 6) or had not yet shown 2 years of stability (n = 5) and were excluded from this study. The remaining 46 papillary lesions constitute our study population.

RESULTS. Surgical excision was performed in 17 (37%) of 46 papillary lesions. In the group of patients whose lesions were recommended for excision because carcinoma was identified at core biopsy, surgical excision revealed one false-positive and two true-positive diagnoses. In four cases, histologic diagnoses of the excisional biopsy and the core needle biopsy were discordant. One false-positive finding at core needle biopsy initially was interpreted as invasive ductal carcinoma on the basis of core needle biopsy specimens. In three false-negative findings, the initial diagnosis at core needle biopsy was upgraded after surgical excision. Two cases of papilloma with adjacent atypical ductal hyperplasia and one of atypical papilloma were upgraded to ductal carcinoma in situ after surgical excision. Imaging follow-up was performed in the remaining 29 patients. All lesions were stable or had decreased in size during the 2-year follow-up period. The negative predictive value of core needle biopsy for excluding malignancy among the papillary lesions diagnosed in our study was 93%.

CONCLUSION. When the histologic diagnosis is benign, our data suggest that papillary lesions may be safely managed with imaging follow-up rather than with surgical excision. However, atypical papillary lesions or those associated with atypia require surgical excision because histologic underestimation occurs at a frequency similar to that in other atypical lesions undergoing core needle biopsy.

OBJECTIVE. Our study investigated the usefulness of contrast-enhanced MR imaging for accurately measuring the size of residual tumor after patients have undergone neoadjuvant (pre-operative) chemotherapy. The imaging analysis method was optimized for identifying residual disease in the treated breast. Tumor sizes measured on the MR images and at the clinical examination were compared with the size of residual disease measured at pathology after surgery.

SUBJECTS AND METHODS. Before undergoing surgery, 52 patients were imaged before and after receiving neoadjuvant chemotherapy. For each patient, specific malignancy criteria were applied to MR images before chemotherapy to identify the location of tumor, and residual disease was then identified as any remaining enhancement in the same area on the MR images after chemotherapy. Residual tumor size was measured using both the MR technique and the clinical examination findings, and the degree of measurement error for each method was assessed in comparison with the pathologic findings.

RESULTS. The correlation with pathology was an r value of 0.89 for MR measurements compared with an r value of 0.60 for clinical measurements. In addition, MR imaging revealed all cases of residual disease, whereas clinical assessment resulted in five false-negative interpretations in the 52 treated lesions.

CONCLUSION. The high correlation between measurements of residual disease obtained on MR images and those obtained at pathology validates the sensitivity of MR imaging of the breast after chemotherapy.

OBJECTIVE. The purpose of our study was to determine the prevalence and types of additional imaging examinations that were performed, and whether anticoagulation therapy was started or continued, after CT angiography showed no pulmonary embolus in a high-risk oncologic population.

MATERIALS AND METHODS. We reviewed the radiology report for each CT angiogram that was obtained for clinically suspected pulmonary embolism at our institution (a tertiary cancer center) during a 25-month period. The radiology information system was then searched for any additional confirmatory radiologic examinations performed within 2 days after a negative finding on CT angiography. Medical records were reviewed to determine whether anticoagulation therapy was started or continued despite a negative finding on CT angiography.

RESULTS. Two hundred seventy-six CT angiograms were obtained in 260 oncology patients who were clinically suspected of having pulmonary embolism. The findings from 203 CT angiograms (74%) were interpreted as negative; 56 (20%), as positive; and 17 (6%), as equivocal for pulmonary embolism. Fifty-eight patients (21%) with negative findings on CT angiography subsequently underwent additional imaging, the results of which were potentially clinically important in 6% of the patients. Six patients began to receive and two continued to undergo anticoagulation therapy despite negative findings on CT angiography; three of the six patients received anticoagulation for new-onset atrial fibrillation.

CONCLUSION. Negative results of CT angiography for pulmonary embolism did not deter referring physicians from ordering other confirmatory imaging tests in 21% of patients in a high-risk oncologic population. Those additional tests rarely revealed results that might have been clinically important.

OBJECTIVE. The purpose of our study was to compare differences in flow between the pulmonary and systemic circulations by assessing MR phase-contrast flow measurements and CT measurements of dilated bronchial arteries in patients with chronic thromboembolic pulmonary hypertension.

MATERIALS AND METHODS. Seventeen patients were included in this study. MR phase-contrast flow measurements were used to calculate the net forward volumes in the right and left pulmonary arteries and in the ascending aorta. Single-detector helical CT scans were assessed for the presence of dilated bronchial arteries that could be delineated from the descending aorta to the mainstem bronchi. Their perpendicular cross-sectional area at the level of the main bronchi was measured using a double-threshold region of interest (≥100-3072 H).

RESULTS. The mean net forward volume in the aorta was 44.6 mL per heartbeat (R-R interval) and in the pulmonary arteries, 30 mL per R-R interval. Thus, the mean difference was 14.6 mL per R-R interval; this value represents the shunt volume between the systemic arterial and pulmonary venous circulations. On CT, dilated bronchial arteries were depicted in all patients (mean, three arteries per patient). The mean cross-sectional area of the bronchial arteries was 0.19 cm². Pearson's correlation coefficient (r) between cross-sectional area and shunt volume was 0.86 (p < 0.01).

CONCLUSION. MR imaging was able to reveal substantial differences in flow between the systemic arterial and pulmonary venous circulations in patients with chronic thromboembolic pulmonary hypertension. These differences correlated well with the diameters of the bronchial arteries seen on helical CT. Furthermore, these differences resolved after pulmonary thromboendarterectomy. MR imaging enables the accurate estimation of flow in the bronchial arteries in patients with chronic thromboembolic pulmonary hypertension.

OBJECTIVE. We assessed the capacity of chest radiography and CT to determine the cause and site of bleeding in patients with either large or massive hemoptysis compared with bronchoscopy.

MATERIALS AND METHODS. We reviewed the chest radiographs, CT scans, and bronchoscopic findings in 80 patients with either large or massive hemoptysis who were admitted to our intensive care unit between January 1995 and June 1999.

RESULTS. Findings on chest radiography were normal in only 13% of patients, of whom 70% had bronchiectasis. The chest radiographs revealed the site of bleeding in 46% of the patients and the cause in 35%, most of whom had tuberculosis or tumors. CT was more efficient than bronchoscopy for identifying the cause of bleeding (77% vs 8%, respectively; p < 0.001), whereas the two methods were comparable for identifying the site of bleeding (70% vs 73%, respectively; p = not significant).

CONCLUSION. These data suggest that CT could replace bronchoscopy as the first-line procedure for screening patients with large and those with massive hemoptysis. However, these results must be confirmed in a prospective multicenter study.

OBJECTIVE. The purpose of this study was to assess the feasibility of performing MR imaging of the chest using a fat-suppressed gadolinium-enhanced modified three-dimensional (3D) gradient-echo technique with a volumetric interpolated breath-hold (VIB) sequence compared with using a standard two-dimensional (2D) breath-hold gradient-echo technique. MR images obtained using both techniques were compared with multidetector CT (MDCT) scans.

SUBJECTS AND METHODS. Paired gadolinium-enhanced 2D gradient-echo and 3D gradient-echo VIB images were acquired in 15 consecutive patients with suspected intrathoracic abnormalities. MDCT scans were available for comparison in 12 patients. Two reviewers independently analyzed the MR images obtained using the two techniques for overall quality, the degree of artifacts, and visibility of mediastinal or parenchymal abnormalities. The detectability of lesions on the 3D gradient-echo VIB images and 2D gradient-echo images was compared with the detectability of lesions on CT scans obtained in nine patients.

RESULTS. In all cases, the MR images obtained using the 3D gradient-echo technique with the VIB sequence were rated superior to those obtained using the 2D gradient-echo technique for quality, depiction of mediastinal structures, and clarity of pulmonary vessels and central airways. On the 3D gradient-echo VIB images, the degree of phase artifacts was lower (p < 0.001), but the degree of pixel graininess was higher (p < 0.05). Detectability, confidence and conspicuity levels, and marginal delineation of the pulmonary lesions were rated higher statistically on the 3D gradient-echo VIB images than on the 2D gradient-echo images. Of the 31 solid pulmonary abnormalities depicted on MDCT, 27 (87.1%) were detected on the 3D gradient-echo VIB images, and 21 (67.7%) were seen on the 2D gradient-echo images (p < 0.05). The 3D gradient-echo VIB images showed all 14 mediastinal lesions (100%) seen on MDCT, whereas the 2D gradient-echo images showed 12 (85.7%) of the 14 lesions (p ≥ 0.05).

CONCLUSION. The gadolinium-enhanced modified 3D gradient-echo technique with the VIB sequence provides MR images that are superior in quality, have significantly fewer artifacts, and have a higher sensitivity for the detection of intrathoracic lesions compared with images obtained using the standard 2D gradient-echo technique.

OBJECTIVE. We hypothesized that radiation doses for abdominal CT could be reduced by adjusting the dose for a patient's weight and cross-sectional abdominal dimensions, with the resultant scans still being of diagnostic quality.

SUBJECTS AND METHODS. Using a multidetector CT scanner, we prospectively studied 39 patients who were 65 years and older who had a known history of cancer. After performing a diagnostic contrast-enhanced CT examination, we obtained four slices each (centered at the top of the right kidney) at a standard radiation dose (240-300 mA) and at a 50% reduced dose (120-150 mA) at a constant kilovoltage of 140. Scans were obtained during a single breath-hold, with a 2.5-mm detector configuration and a slice pitch of 6:1. Reconstructed slice thickness was 5 mm. In a blinded review, two radiologists rated the randomized CT scans for overall image quality and anatomic details of liver, spleen, adrenal glands, kidneys, pancreas, and abdominal wall, using a 5-point scale (1 = unacceptable, 2 = substandard, 3 = acceptable, 4 = above average, and 5 = superior). Patients' weight and abdominal circumference, area, and anteroposterior and transverse diameters were correlated with image quality of scans obtained at standard-dose and 50% reduced—dose CT. Statistical analysis of the data was performed using Wilcoxon's signed rank test.

RESULTS. Overall, the image quality score was significantly higher (p < 0.005) on the scans obtained with standard-dose CT. No statistically significant difference in image quality was noted in the 50% reduced— and standard-dose CT scans in patients who weighed less than 180 lb, or 81 kg, (p > 0.05) and who had a transverse abdominal diameter of less than 34.5 cm (p > 0.05), an anteroposterior diameter of less than 28 cm (p > 0.05), a cross-sectional circumference of less than 105 cm (p > 0.05), and a cross-sectional area of less than 800 cm² (p > 0.05). Good interobserver agreement (p > 0.5) was found between the two reviewing radiologists.

CONCLUSION. Abdominal CT scan quality appears to be acceptable even with a 50% reduction in radiation dose except in patients with large anthropometric measurements. A reduction in CT radiation dose is possible if the tube current is optimized for the patient's weight and abdominal dimensions.

OBJECTIVE. Limiting CT radiation dose is especially critical when imaging children. The purpose of our study was to modify and test an accurate and safe tool for evaluating systematic dose reduction for abdominal multidetector CT (MDCT) in pediatric patients.

MATERIALS AND METHODS. After validating the computer-simulation technique with a water phantom, we subjected the original digital scanning data for 26 contrast-enhanced abdominal MDCT scans (120 mA) obtained in infants and children (age range, 1 month-9 years; mean age, 3.1 years) to simulated tube current reduction (100, 80, 60, and 40 mA) by adding noise. this procedure created four additional examinations per child that were identical to the originals except for image noise. The 130 examinations were scored randomly, independently, and without prior knowledge of the children's diagnoses by three radiologists for depiction of high-visibility structures, such as adrenal glands and fat in the intrahepatic falciform ligament, and low-visibility structures, such as the extrahepatic hepatic artery, small intrahepatic vessels, and common bile duct. Aligned rank and Wilcoxon's signed rank tests were used for statistical analyses.

RESULTS. Simulated tube current reduction significantly affected the detection of low-visibility structures (p < 0.001). Reduced detection in low-visibility structures was evident at a level less than or equal to 80 mA. No loss of detection in high-visibility structures was found at any tube current level (p > 0.5).

CONCLUSION. The results of this computer simulation suggest that accurate abdominal MDCT can be performed in pediatric patients using substantially reduced radiation, depending on the indication for imaging. (In our case, the reduction was between 33% and 67%, depending on whether a high-visibility or low-visibility structure was being assessed.) This simulation technology can be applied to MDCT of other organ systems for systematic evaluation of radiation dose reduction.

OBJECTIVE. We undertook this study to assess how well double-contrast radiography and CT allow radiologists to differentiate low-grade from high-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach.

MATERIALS AND METHODS. We retrospectively reviewed the upper gastrointestinal radiographs and contrast-enhanced CT scans of 57 patients with pathologically proven primary gastric lymphoma (low-grade [n = 29] and high-grade [n = 28] MALT lymphoma).

RESULTS. On upper gastrointestinal radiography, ulceration (39%) was the most common finding in low-grade lymphoma, whereas polypoid appearance (38%) was the most common in high-grade lymphoma. In the 29 patients (33 lesions) with low-grade MALT lymphoma, upper gastrointestinal radiography revealed 13 ulcerative lesions (39%), 10 nodular lesions (30%), four infiltrative lesions (12%), two polypoid lesions (6%), and four combined lesions (12%). In the 28 patients (29 lesions) with high-grade lymphoma, upper gastrointestinal radiography revealed 11 polypoid lesions (38%), nine infiltrative lesions (31%), six ulcerative lesions (20%), one nodular lesion (3%), and two combined lesions (7%). On CT, thickening of the gastric wall in low-grade lymphoma (range, 0.3-2.5 cm; mean, 0.8 cm) was much less than that in high-grade lymphoma (range, 0.7-8.0 cm; mean, 2.5 cm). Abdominal lymphadenopathy was less frequent in low-grade lymphoma (14%) than in high-grade lymphoma (75%).

CONCLUSION. Most low-grade lymphomas show superficial spreading lesions, such as mucosal nodularity, shallow ulcer, and minimal fold thickening, on upper gastrointestinal radiography, whereas most high-grade lymphomas show mass-forming lesions or severe fold thickening.

OBJECTIVE. We assessed the ability of contrast-enhanced sonography to reveal differences between benign and malignant focal hepatic lesions.

SUBJECTS AND METHODS. We examined 67 patients with focal hepatic lesions in a prospective study. The causes of the lesions were confirmed by histology, CT, MR imaging, or scintigraphy. The liver was screened for focal lesions using sonography. Thereafter, 2 g of Levovist (300 mg/mL; 1 mL/sec) was injected IV as a bolus. After a delay of at least 2.5 min without scanning, the liver was examined via three different scans using pulse-inversion sonography.

RESULTS. For the discrimination of malignant versus benign liver lesions, contrast-enhanced sonography improved sensitivity from 85% to 100% and specificity from 30% to 63%, as compared with baseline sonography. Receiver operating characteristic analysis revealed a significant improvement in this discrimination (A_z = 0.692 ± 0.065 at baseline sonography, A_z = 0.947 ± 0.037 with contrast-enhanced sonography, p < 0.001). Furthermore, a lower interobserver variability was found for contrast-enhanced sonography (weighted κ = 0.947), as compared with baseline sonography (weighted κ = 0.469). All lesions that had homogeneous enhancement in the late phase of Levovist enhancement were benign. In distinction, 90% of lesions without contrast enhancement in the late phase were malignant. All lesions were malignant that were isoechoic (invisible) on baseline sonography but visible because of lack of enhancement after injection.

CONCLUSION. Contrast-enhanced sonography has greater specificity and sensitivity than baseline sonography for the differentiation of benign and malignant liver lesions.

OBJECTIVE. Although splenectomy is a standard surgical treatment for chronic idiopathic thrombocytopenic purpura, partial splenic embolization is another treatment option. We retrospectively studied the long-term results of initial and repeated partial splenic embolization.

MATERIALS AND METHODS. Thirty-nine patients, 15 men and 24 women, underwent initial embolization; 12 of the 39 underwent a repeated embolization. The therapeutic effects of the initial and repeated embolization were classified as a complete response if the patient's platelet count rose to more than 10 × 10⁴/μL without medication 1 year after the initial or repeated embolization, as a partial response if the platlet count reached 5-10 × 10⁴/μL under the same circumstances, or as no response.

RESULTS. Twenty patients (51%) responded to the initial embolization (complete response in 11 and partial response in nine). No significant differences were found between those patients who responded to the treatment (responders) and those who did not respond to the treatment (nonresponders) in age, sex, lowest platelet counts, and steroid response before embolization. Peak platelet response was significantly higher in the responders (p = 0.029). One of the 11 complete responders and five of the nine partial responders relapsed after a median follow-up period of 34 months (range, 15-23 months) and underwent repeated embolization, resulting in complete response in one patient, partial response in the remaining four patients, and no response in one patient. However, in the six nonresponders (to the initial embolism), repeated embolization elicited a partial response in only one patient. The remission rate of 51% was maintained by means of repeated embolization for a median follow-up period of 76 months after the initial embolization.

CONCLUSION. Partial splenic embolization combined with repeated embolization may be an effective alternative to splenectomy in the treatment of chronic idiopathic thrombocytopenic purpura.

OBJECTIVE. The purpose of our study was to investigate the potential of FDG positron emission tomography (PET) to distinguish viable tumor from changes caused by therapy in areas with equivocal MR imaging findings in patients with musculoskeletal sarcomas.

MATERIALS AND METHODS. We evaluated 12 patients (nine males, three females; age range, 9-56 years; mean age, 25 years) with a history of bone or soft-tissue sarcoma who had undergone various treatments (surgery, chemotherapy, radiation therapy, or a combination of treatments) and who presented with clinically suspected recurrent or residual tumor. All patients underwent gadopentetate dimeglumine—enhanced MR imaging and whole-body FDG PET. Imaging results were correlated with histologic findings or with clinical findings from long-term follow-up.

RESULTS. In nine patients, MR imaging findings were equivocal in differentiating between posttherapeutic changes and tumor recurrence. FDG PET images showed increased uptake, suggestive of recurrent tumor, in five patients. These findings were confirmed by biopsy. Four patients showed no increased uptake on FDG PET and were closely monitored clinically. No tumor recurrence was found in these patients. One patient showed MR imaging findings suggestive of recurrent tumor that was confirmed on FDG PET and at histology. Two patients underwent a limb salvage procedure before MR imaging, but MR images were deemed inadequate for interpretation because of extensive metallic artifacts. FDG PET was helpful in evaluating these patients for tumor recurrence.

CONCLUSION. FDG PET is a useful adjunct to MR imaging in distinguishing viable tumor from posttherapeutic changes in patients with bone and soft-tissue sarcomas.

OBJECTIVE. The objective of our study was to evaluate the usefulness of FDG positron emission tomography (PET) for the differentiation of degenerative and infectious endplate abnormalities in the lumbar spine that were detected on MR imaging.

SUBJECTS AND METHODS. FDG PET was performed prospectively in 30 consecutive patients with substantial endplate abnormalities (craniocaudal diameter of bone marrow abnormalities, ≥ 25% of vertebral height) found during MR imaging of the lumbar spine. Both the MR and PET images were evaluated by two experienced musculoskeletal radiologists and two experienced nuclear physicians. The diagnosis of either degeneration with different types of endplate abnormalities or disk-space infection was determined. Clinical follow-up and, in selected cases, bone biopsies with cultures were used as the standard of reference.

RESULTS. On the MR images, 25 of the 38 degenerated levels were classified as Modic type I, 13 levels as type II, and none as type III. Five disk-space infections were diagnosed in four patients. MR imaging findings were false-positive at one disk level with type I abnormalities and false-negative at two levels with infection. PET did not show FDG uptake in the intervertebral spaces of any patient with degenerative disease. FDG PET findings were true-positive in all five levels with disk-space infection. The sensitivity and specificity for MR imaging in detecting disk-space infection were 50% and 96%, and were 100% and 100% for FDG PET, respectively (not significant, McNemar test, p = 0.5).

CONCLUSION. Our findings suggest that FDG PET may prove useful for differentiation of degenerative and infectious endplate abnormalities detected on MR imaging. Even in active (Modic type I) degenerative endplate abnormalities in our series, PET did not show increased FDG uptake.

OBJECTIVE. The objective of this work was to determine the accuracy of fast spin-echo proton density-weighted MR imaging in the evaluation of the articular cartilage of the knee using arthroscopy as a gold standard.

MATERIALS AND METHODS. We retrospectively reviewed MR images of the knee in 54 patients for whom arthroscopic results were available. All MR imaging studies included fast spin-echo proton density-weighted coronal and axial sequences as part of our routine protocol. Evaluation of the articular surfaces was performed by three independent observers who were unaware of the arthroscopic results. The cartilage surfaces were graded using a 3-point system, and results were compared with arthroscopic findings.

RESULTS. Of 324 cartilage surfaces evaluated, arthroscopy showed 241 surfaces as normal, 56 as containing partial-thickness defects, and 27 as containing full-thickness defects. Compared with arthroscopic data, sensitivity of MR imaging for the three reviewers was 59-73.5%; specificity, 86.7-90.5%; positive predictive value, 60.5-72.6%; negative predictive value, 86.0-90.8%; and accuracy, 79.6-86.1%. Interobserver variability for the presence of disease, which was measured using the kappa statistic, was 0.63.

CONCLUSION. Fast spin-echo proton density-weighted MR imaging sequences can be used to evaluate the cartilage of the knee with accuracy comparable to that of previously reported cartilage-specific sequences.

OBJECTIVE. Plantar fibromatosis is a rare benign fibroproliferative disorder of the plantar fascia that can be evaluated on sonography. Our study details the sonographic appearances of plantar fibromatosis.

MATERIALS AND METHODS. We conducted a retrospective review of the clinical presentation, sonographic appearances, and clinical progress in 14 patients (range, 35-85 years; mean age, 53.1 years;) with plantar fibromatosis. Sonography was performed using either a 13-5—MHz multidimensional or 12.5-MHz linear array transducer. The location, sonographic appearances, and size of the plantar fibromatosis nodules were noted and correlated with symptom duration and clinical outcome.

RESULTS. A total of 25 fibromatosis nodules in 19 feet were examined. On sonography, plantar fibromatosis was seen as a discrete fusiform nodular thickening of the plantar fascia, separate from the calcaneal insertion. Approximately one third (36%) of lesions were bilateral, and one quarter (26%) were multiple. All lesions were located either medially (60%) or centrally (40%) in the fascia. Most were hypoechoic (76%), were well defined (64%), and showed no acoustic enhancement (80%) or intrinsic vascularity (92%). No correlation was found between the echogenicity and size of plantar fibromatosis nodules or duration of symptoms (p < 0.01). One quarter of the affected feet had coexistent thickening of the plantar fascia at the calcaneal insertion with no related symptoms.

CONCLUSION. Although the sonographic appearances of plantar fibromatosis vary, the appearances are characteristic enough to allow a specific diagnosis to be made. No clear relationship was found among the sonographic appearances, duration of symptoms, or clinical outcome.

OBJECTIVE. Systemic mastocytosis is a hematologic neoplasm characterized by abnormal accumulation and growth of mast cells in one or more organ systems. We analyzed five patients with systemic mastocytosis referred for FDG positron emission tomography who had biopsy-proven mast cell infiltrates in various organs.

CONCLUSION. Our findings indicate that FDG positron emission tomography is not useful for staging and follow-up of aggressive systemic mastocytosis.

OBJECTIVE. The purpose of this article is to present serial clinical and imaging findings for the “absent” pulmonary artery. Data from six patients with this condition (five unilateral cases and one bilateral case) provide evidence concerning its embryology and illustrate the therapeutic implications of surgical intervention.

CONCLUSION. In our series, we found the anatomy of the absent pulmonary artery to be consistent with a distal ductal origin and involution of the proximal sixth aortic arch. The absent pulmonary artery is a distinct embryologic entity that requires early detection and detailed investigation. Early surgical intervention may be justified in selected patients.

OBJECTIVE. The purpose of this study was to assess the ability of whole-body turbo short tau inversion recovery (STIR) MR imaging to detect metastases in children with small cell tumors and to compare its performance with that of conventional imaging.

CONCLUSION. Early data suggest that whole-body turbo STIR MR imaging is as reliable as other conventional imaging studies for staging newly diagnosed small cell tumors in pediatric patients.

OBJECTIVE. The purpose of this report is to describe the role of MR imaging in the diagnosis of focal pyomyositis surrounding the sciatic nerve in children.

CONCLUSION. In the absence of joint effusion on sonography, MR imaging should be considered in pediatric patients who present with a febrile illness and incapacitating pelvic pain.

OBJECTIVE. The purpose of our study was to assess the usefulness of mangafodipir trisodium—enhanced MR cholangiography for evaluating intrahepatic biliary anatomy of adult living liver donors and to correlate the results with intraoperative cholangiography.

CONCLUSION. Mangafodipir trisodium—enhanced MR cholangiography accurately shows the biliary anatomy in the livers of donors. Noninvasive preoperative evaluation of the biliary anatomy in donor candidates is important for the detection of common anatomic variants that may require alternative graft-harvesting surgery.

OBJECTIVE. The aim of this study was to establish objective, simple criteria for bronchial wall thickening in children with difficult-to-treat asthma.

SUBJECTS AND METHODS. Bronchial sections were counted at five levels in both lungs and at three levels in the right lung on high-resolution CT and plotted against lung function. Findings from 27 children with persistent symptoms of asthma (mean age, 11.4 years; SD, ±3.1 years) that were severe (group A, n = 15) or moderate (group B, n = 12) were compared with findings from 21 control subjects (mean age, 10.8 years; SD, ±3.0 years) using the Student's t test, analysis of variance, and Dunn-Bonferroni test.

RESULTS. A bronchial wall thickening score based on the number of visible bronchi at three levels (three-level score) proved to be as valuable as and simpler to obtain than a score based on the number of bronchi at five levels (five-level score). The three-level scores for groups A and B were similar (mean ± SD, 16.8 ± 4.2 vs 18.4 ± 3.4, respectively; p = not significant), but these scores were significantly higher than those for the control subjects (mean ± SD, 8.2 ± 3.4, respectively; p < 0.001). There was no correlation between the three-level score and forced expiratory volume in 1 sec or forced expiratory flow between 25% and 75% of forced vital capacity. In contrast with adults with severe asthma, our pediatric patients with difficult-to-treat asthma did not have CT evidence of mucoid impaction, emphysema, areas of hyperlucency, bronchiectasis, or sequellar line shadows.

CONCLUSION. Bronchial wall thickening visible on high-resolution CT may constitute an additional criterion of asthma severity in children. CT evidence of bronchial wall thickening might help to identify patients with a higher risk of airway remodeling.

OBJECTIVE. Our objective was to evaluate the detectability of in-stent stenoses in iliac artery stents using multidetector CT angiography in comparison with MR angiography and digital radiographic angiography.

MATERIALS AND METHODS. Ten different metallic stents (made of steel, nitinol, tantalum, or cobalt) were implanted in plastic tubes (8 mm). The stent lumina were partially obstructed by wax (CT density, -30 H) resulting in 50-60% in-stent stenoses. The tubes were filled with diluted contrast material (25 mmol/L of gadopentetate dimeglumine or 6 mg I/mL of iodinated contrast material) and placed in a plastic container filled with oil or water, respectively. CT angiography was performed on a four-detector CT scanner (detector collimation, 4 × 1 mm; slice thickness, 1.25 mm; table feed, 4 mm per rotation). MR angiography was performed on a 1.5-T system with a three-dimensional gradient-echo sequence (TR/TE, 4.6/1.8; flip angle, 30°; slice thickness, 1.88 mm). Axial and longitudinal reformations of CT and MR imaging data were evaluated regarding the in-stent attenuation and signal intensity, the visible lumen diameter inside the stent, and the delineation of the stenoses. For comparison, digital radiographic angiography was performed as the gold standard.

RESULTS. The degree and character of stent-related artifacts differed in CT angiography and MR angiography. In CT angiography, only the tantalum stent caused artifacts that obscured the stenosis; in all other cases, the stenoses were visible. In MR angiography, depiction of stenoses was impaired in two steel stents but possible in the tantalum and most nitinol stents.

CONCLUSION. CT angiography is suited for detection of relevant stenoses in steel, cobalt-based, and nitinol stents. MR angiography is superior only in tantalum products.