Materials and Methods: Institutional review committee approval and informed consent were obtained. Sixty patients with heart rates of less than 75 beats per minute who were referred for coronary CT angiography were enrolled. Both prospective and retrospective CT angiography were performed with a 64-detector scanner. Data acquisition times were recorded. Two independent cardiac radiologists evaluated subjective image quality (1, excellent; 4, poor) and severity of stenosis (0% occlusion, 1%–49% occlusion, 50%–75% occlusion, and >75% occlusion) with the 17-segment American Heart Association classification model. Discrepancies were settled by consensus. Effective radiation doses of prospective and retrospective CT angiography were calculated with volume CT dose index. Data regarding acquisition time and radiation exposure for prospective and retrospective CT angiography were compared. The Student t test was performed, and statistics were calculated.

Results: Mean data acquisition time of prospective CT angiography was shorter than that of retrospective CT angiography (5.6 seconds ± 1.1 [standard deviation] vs 6.7 seconds ± 1.1, respectively; P < .01). Consensus-determined image quality in coronary artery branches was similar between prospective CT angiography and retrospective CT angiography (1.15 vs 1.13, respectively; P = .992). Excellent agreement between prospective CT angiography and retrospective CT angiography was observed in the detection of significant (≥50% occlusion) coronary artery stenoses per segment ( = 0.882) and in the grading of stenoses per patient ( = 0.829). Calculated effective dose with prospective CT angiography was 79% lower than that with retrospective CT angiography (4.1 mSv ± 1.8 vs 20.0 mSv ± 3.5, respectively; P < .001).

Conclusion: Prospective CT angiography can reduce radiation dose below that of retrospective CT angiography with dose modulation, while maintaining image quality and the ability to assess luminal obstructions in patients with heart rates of less than 75 beats per minute.

© RSNA, 2008

Materials and Methods: The database consisted of consecutive diagnostic breast US scans collected with informed consent with a protocol approved by the institutional review board and compliant with the HIPAA. Images from 508 patients with a total of 1046 distinct abnormalities were used. One hundred one patients had breast cancer. Results both for patients in whom the lesion abnormality was proved with either biopsy or aspiration (n = 183) and for all patients irrespective of biopsy status (n = 508) are presented. The ability of the CAD workstation to help differentiate malignancies from benign lesions was evaluated with a leave-one-out-by-case analysis. The clinical specificity of the radiologists for this dataset was determined according to the biopsy rate and outcome.

Results: In the task of differentiating cancer from all other lesions sent to biopsy, the CAD workstation obtained an area under the receiver operating characteristic curve (AUC) value of 0.88, with 100% sensitivity at 26% specificity (157 cancers and 362 lesions total). The radiologists' specificity at 100% sensitivity for this set was zero. When analyzing all lesions irrespective of biopsy status, which is more representative of actual clinical practice, the CAD scheme obtained an AUC of 0.90 and 100% sensitivity at 30% specificity (157 cancers and 1046 lesions total). The radiologists' specificity at 100% sensitivity for this set was 77%.

Conclusion: Current levels of computer performance warrant a clinical evaluation of the potential of US CAD to aid radiologists in lesion work-up recommendations.

© RSNA, 2008

Materials and Methods: All experiments were conducted with animal care and use committee approval. Murine SCC cells were implanted subcutaneously in C3H mice. When tumors reached 100 mm³, mice were randomized to one of three groups for twice weekly intraperitoneal injections of 1.5 mg of bortezomib per kilogram of body weight, a proteasome inhibitor (n = 10); 1.0 mg/kg bortezomib (n = 11); or a control vehicle (n = 12). Within each group, half of the mice received pulsed HIFU exposure to their tumors immediately prior to each injection. The time for tumors to reach 650 mm³ was compared among groups. Additional tumors were stained with terminal deoxynucledotidyl transferase-mediated dUTP nick end labeling and CD31 to assess apoptotic index and blood vessel density, respectively.

Results: Tumors in the control group, pulsed HIFU and control group, and 1.0 mg/kg of bortezomib alone group reached the size end point in 5.2 days ± 0.8 (standard deviation), 5.3 days ± 0.8, and 5.6 days ± 1.1, respectively. However, pulsed HIFU and 1.0 mg/kg bortezomib increased the time to end point to 9.8 days ± 2.9 (P < .02), not significantly different from the 8.8 days ± 2.1 in tumors treated with 1.5 mg/kg bortezomib alone (P > .05). Combination therapy was also associated with a significantly higher apoptotic index (P < .05).

Conclusion: Treatment of tumors with pulsed HIFU lowered the threshold level for efficacy of bortezomib, resulting in significant tumor cytotoxicity and growth inhibition at lower dose levels.

© RSNA, 2008

© RSNA, 2008

Materials and Methods: Forty-five consecutive patients (27 men, 18 women; mean age, 64 years) underwent contrast material–enhanced MR angiography of the lower extremities at 3.0 T. A waiver of informed consent was granted by the institutional review board. Sixteen patients received high-dose (approximately 0.3 mmol/kg), 15 received intermediate-dose (approximately 0.2 mmol/kg), and 14 received low-dose (approximately 0.1 mmol/kg) gadopentetate dimeglumine during a three-station, dual-injection examination. For scoring purposes, the arterial system from the celiac trunk to the plantar arteries was divided into 34 segments. The images were retrospectively and independently evaluated by two specialized radiologists who were blinded to the patient dose groups. All studies were assessed for overall image quality and the degree of contaminating venous enhancement. Each arterial segment was scored for the quality of vessel definition, the severity of stenoses, and the presence of collateral vessels.

Results: More than 99% of arterial segments were found to be of diagnostic image quality by both readers in all dose groups. Generalized estimating equation analysis showed a significant difference among the three groups with regard to vessel definition (P = .019). No significant difference was found between the high- and intermediate-dose groups; however, the low-dose group had significantly better vessel definition compared with the high-dose (P = .034) and intermediate-dose (P = .015) groups. There was no significant difference among the groups in visualization of collateral vessels. Venous contamination was seen less frequently in the low-dose group, but the difference did not achieve significance.

Conclusion: The study showed that, compared with widely used dose strategies at 1.5 T, the contrast agent dose for 3.0-T lower extremity MR angiography can be reduced multifold without compromising image quality.

© RSNA, 2008

Materials and Methods: Twenty participants (mean age, 69.8 years [standard deviation] ± 10.5; 75% men) with 16%–79% carotid stenosis at duplex ultrasonography were imaged with 1.5-T and 3.0-T MR imaging units with bilateral four-element phased-array surface coils. This HIPAA-compliant study was approved by the institutional review board, and all participants gave written informed consent. Protocols designed for similar signal-to-noise ratios across platforms were implemented to acquire axial T1-weighted, T2-weighted, intermediate-weighted, time-of-flight, and contrast material–enhanced T1-weighted images. Lumen area, wall area, total vessel area, wall thickness, and presence or absence and area of plaque components were documented. Continuous variables from different field strengths were compared by using the intraclass correlation coefficient (ICC) and repeated measures analysis. The Cohen was used to evaluate agreement between 1.5 T and 3.0 T on compositional dichotomous variables.

Results: There was a strong level of agreement between field strengths for all morphologic variables, with ICCs ranging from 0.88 to 0.96. Agreement in the identification of presence or absence of plaque components was very good for calcification ( = 0.72), lipid-rich necrotic core ( = 0.73), and hemorrhage ( = 0.66). However, the visualization of hemorrhage was greater at 1.5 T than at 3.0 T (14.7% vs 7.8%, P < .001). Calcifications measured significantly (P = .03) larger at 3.0 T, while lipid-rich necrotic cores without hemorrhage were similar between field strengths (P = .9).

Conclusion: At higher field strengths, the increased susceptibility of calcification and paramagnetic ferric iron in hemorrhage may alter quantification and/or detection. Nevertheless, imaging criteria at 1.5 T for carotid vessel wall interpretation are applicable at 3.0 T.

© RSNA, 2008

Materials and Methods: This study had institutional review board approval, and informed consent was obtained from all participants. There were 59 women:15 nulliparous study control women (mean age, 25.6 years) and 44 patients (mean age, 43.4 years), who were divided into four groups according to chief symptom. Static T2-weighted turbo spin-echo images were used in evaluating structural derangements; functional dynamic (cine) balanced fast-field echo images were used in detecting functional abnormalities and recording five measurements of supporting structures. Findings on both types of MR images were analyzed together to determine the predominant defect. Analysis of variance and the Bonferroni t test were used to compare groups.

Results: In the four patient groups, POP was associated with levator muscle weakness in 16 (47%) of 34 patients, with level I and II fascial defects in seven (21%) of 34 patients, and with both defects in 11 (32%) of 34 patients. SUI was associated with defects of the urethral supporting structures in 25 (86%) of 29 patients but was not associated with bladder neck descent. Levator muscle weakness may lead to anal incontinence in the absence of anal sphincter defects. Measurements of supporting structures were significant (P < .05) in the identification of pelvic floor laxity.

Conclusion: Combined analysis of static and dynamic MR images of patients with pelvic floor dysfunction allowed identification of certain structural abnormalities with specific dysfunctions.

© RSNA, 2008

Materials and Methods: This study was IRB approved; written informed consent was obtained; and included 65 AD patients (38 women, 27 men; age, 52–81 years), 45 MCI patients (22 women, 23 men; age, 56–80 years), 27 patients with subjective complaints (12 women, 15 men; age, 50–87 years), and 10 healthy controls (six women, four men; age, 53–80 years). Two magnetic resonance (MR) images were acquired at average interval of 1.8 years ± 0.7 (standard deviation). Baseline brain volume and whole-brain atrophy rates were measured on three-dimensional T1-weighted MR images (1.0 T; single slab, 168 sections; matrix size, 256 x 256; field of view, 250 mm; voxel size, 1 x 1 x 1.5 mm; repetition time msec/echo time msec/inversion time msec, 15/7/300; and flip angle, 15°). Associations were assessed by using partial-correlations. Cox proportional hazards models were used to estimate risk of developing dementia.

Results: Baseline brain volume was lowest in AD but did not differ significantly between MCI, subjective complaints, and control groups (P > .38). Whole-brain atrophy rates were higher in AD (–1.9% per year ± 0.9) than MCI (–1.2% per year ± 0.9, P = .003) patients, who had higher whole-brain atrophy rates than patients with subjective complaints (–0.7% per year ± 0.7, P = .03) and controls (–0.5% per year ± 0.5, P = .05). Whole-brain atrophy rate correlated with annualized Mini-Mental State Examination (MMSE) change (r = 0.48, P < .001), while baseline volume did not (r = 0.11, P = .22). Cox models showed that—after correction for age, sex, and baseline MMSE—a higher whole-brain atrophy rate was associated with an increased risk of progression to dementia (highest vs lowest tertile [hazard ratio, 3.6; 95% confidence interval: 1.2, 11.4]).

Conclusion: Whole-brain atrophy rate was strongly associated with cognitive decline. In nondemented participants, a high whole-brain atrophy rate was associated with an increased risk of progression to dementia.

© RSNA, 2008

Materials and Methods: Institutional review board approval was obtained for this HIPAA-compliant study, and the informed consent requirement was waived due to the retrospective study design. Two independent reviewers separately scored coronary artery segment image quality and overall image quality for 100 cardiac CT studies (50 in each group). Interobserver variability was calculated. Patient radiation dose for the actual examination z-axis length was recorded, and a normalized dose was calculated for a 12-cm z-axis length of a typical heart.

Results: The two groups matched well for clinical characteristics and CT parameters. There was good agreement for coronary artery segment image quality scores between the independent reviewers ( = 0.72). Of the 1253 coronary artery segments scored, the number of coronary artery segments that could not be evaluated in each group was similar (1.1% [seven of 614] in the prospective group vs 1.5% [10 of 647] in the retrospective group, P = .53). Image quality scores were not significantly different when matched for chest cross-sectional area (P > .05). Mean patient radiation dose was 77% lower for prospective gating (4.2 mSv) than for retrospective gating (18.1 mSv) (P < .01).

Conclusion: Use of 64-detector CT coronary angiography performed with prospective ECG gating has similar subjective image quality scores but 77% lower patient radiation dose when compared with use of retrospective ECG gating.

© RSNA, 2008

Materials and Methods: Institutional review board approval and informed consent were obtained. The study included 165 patients (125 men, 40 women; mean age, 61 years) with NSCLC proved at pathologic examination who underwent both unenhanced PET/CT and whole-body MR imaging. Pathologic findings for T (n = 123) and N (n = 150) staging and pathologic or follow-up imaging findings (n = 154) for M staging were reference standards. The efficacies of PET/CT and whole-body MR imaging for lung cancer staging were compared by using the McNemar test.

Results: Primary tumors (n = 123 patients) were correctly staged in 101 (82%) patients at PET/CT and in 106 (86%) patients at whole-body MR imaging (P = .263). N stages (n = 150 patients) were correctly determined in 105 (70%) patients at PET/CT and in 102 (68%) patients at whole-body MR imaging (P = .880). Thirty-one (20%) of 154 patients had metastatic lesions. Accuracy for detecting metastases was 86% (133 of 154 patients) at PET/CT, and that at whole-body MR imaging was 86% (132 of 154 patients) (P > .99). Although the differences were not statistically significant, whole-body MR imaging was more useful for detecting brain and hepatic metastases, whereas PET/CT was more useful for detecting lymph node and soft-tissue metastases.

Conclusion: Both PET/CT and 3.0-T whole-body MR imaging appear to provide acceptable accuracy and comparable efficacy for NSCLC staging, but for M-stage determination, each modality has its own advantages.

© RSNA, 2008

Materials and Methods: All patients gave written informed consent after the study details, including radiation exposure, were explained. The study protocol was approved by the local institutional review board. In patients referred for elective conventional coronary angiography, an additional 64-section CT angiography study and a myocardial perfusion imaging study (1-day adenosine stress-rest protocol) with technetium 99m–tetrofosmin SPECT were performed before conventional angiography. Coronary artery diameter narrowing of 50% or greater at CT angiography was defined as stenosis and was compared with the myocardial perfusion imaging findings. Quantitative coronary angiography served as a reference standard for CT angiography.

Results: A total of 1093 coronary segments in 310 coronary arteries in 78 patients (mean age, 65 years ± 9 [standard deviation]; 35 women) were analyzed. CT angiography revealed stenoses in 137 segments (13%) corresponding to 91 arteries (29%) in 46 patients (59%). SPECT revealed 14 reversible, 13 fixed, and six partially reversible defects in 31 patients (40%). Sensitivity, specificity, and negative and positive predictive values, respectively, of CT angiography in the detection of reversible myocardial perfusion imaging defects were 95%, 53%, 94%, and 58% on a per-patient basis and 95%, 75%, 96%, and 72% on a per-artery basis. Agreement between CT and conventional angiography was very good (96% and = 0.92 for patient-based analysis, 93% and = 0.84 for vessel-based analysis).

Conclusion: Sixty-four–section CT angiography can help rule out hemodynamically relevant CAD in patients with intermediate to high pretest likelihood, although an abnormal CT angiography study is a poor predictor of ischemia.

© RSNA, 2008

Materials and Methods: Informed consent was waived by the Institutional Review Board for this HIPAA-compliant study. The study group consisted of 32 skeletally immature patients (25 boys, seven girls; mean age, 14.4 years) with 36 juvenile OCD lesions of the knee and 33 skeletally mature patients (25 men, eight women; mean age, 26.2 years) with 34 adult OCD lesions of the knee. All patients had been evaluated with MR imaging and arthroscopy. MR studies were retrospectively reviewed by two radiologists in consensus to determine the presence of previously described MR imaging criteria for OCD instability (ie, high T2 signal intensity rim, surrounding cysts, high T2 signal intensity cartilage fracture line, and fluid-filled osteochondral defect). Sensitivity and specificity of the criteria were calculated separately for juvenile and adult OCD lesions.

Results: Separately, previously described MR imaging criteria for detection of OCD instability were 0%–88% sensitive and 21%–100% specific for juvenile OCD lesions and 27%–54% sensitive and 100% specific for adult OCD lesions. When used together, the criteria were 100% sensitive and 11% specific for instability in juvenile OCD lesions and 100% sensitive and 100% specific for instability in adult OCD lesions.

Conclusion: Previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee.

© RSNA, 2008

Materials and Methods: The institutional review board approved this study; informed consent was obtained from patients. A total of 203 NSCLC patients (109 men, 94 women; mean age, 72 years) prospectively underwent whole-body DW imaging, whole-body MR imaging, and FDG PET/CT. Final diagnosis of the M-stage in each patient was determined on the basis of results of all radiologic and follow-up examinations. Two chest radiologists and two nuclear medicine physicians independently assessed all examination results and used a five-point visual scoring system to evaluate the probability of metastases. Final diagnosis based on each of the methods was made by consensus of two readers. Receiver operating characteristic (ROC) analysis was used to compare the capability for M-stage assessment among whole-body DW imaging, whole-body MR imaging with and that without DW imaging, and PET/CT on a per-patient basis. Sensitivity, specificity, and accuracy were compared with the McNemar test.

Results: Area under ROC curve (A_z) values of whole-body MR imaging with DW imaging (A_z = 0.87, P = .04) and integrated FDG PET/CT (A_z = 0.89, P = .02) were significantly larger than that of whole-body DW imaging (A_z = 0.79). Specificity and accuracy of whole-body MR imaging with (specificity, P = .02; accuracy, P < .01) and that without DW imaging (specificity, P = .02; accuracy, P = .01) and integrated FDG PET/CT (specificity, P < .01; accuracy, P < .01) were significantly higher than those of whole-body DW imaging.

Conclusion: Whole-body MR imaging with DW imaging can be used for M-stage assessment in NSCLC patients with accuracy as good as that of PET/CT.

© RSNA, 2008

Materials and Methods: This HIPAA-compliant study was approved by the ethics committee of the institution, and all patients provided written informed consent. Fifty-eight patients (13 men and 45 women [mean age, 51 years; range, 20–76 years]) were enrolled. A short US examination and elastography with pulsation of the carotid artery used as the thyroid compression source were performed before fine-needle aspiration. Baseband US data were downloaded for off-line analysis. Elastographic maps and the thyroid stiffness index were calculated. The Kruskal-Wallis nonparametric rank sum test was used to assess equality of population medians among the different types of thyroid nodules; the R software environment was used for statistical computing and graphics (http://www.r-project.org/).

Results: Thyroid stiffness index calculated with elastography using carotid arterial pulsation as the compression source was effective in helping distinguish between papillary carcinomas (n = 10) and other lesions (n = 43) because papillary carcinomas were stiffer than other lesions (P < .0039).

Conclusion: It is possible to distinguish between papillary carcinomas and other lesions with the thyroid stiffness index calculated from US elastography using carotid arterial pulsation.

© RSNA, 2008

Materials and Methods: This study was approved by the institutional review board, and the methods comply with HIPAA regulations. A retrospective search of the institutional mammographic results database was done to identify bilateral screening mammographic examinations obtained from January 1, 1999, through July 15, 2005. The search included the term TRAM; the recall and cancer detetion rates were then detected. Subsequently, a decision analytic model was constructed to evaluate a hypothetical cohort of women with TRAM flap reconstructions.

Results: Of 554 mammograms (265 TRAM flap reconstructions), 546 (98.6%) had negative results (Breast Imaging Reporting and Data System category 1 or 2). Eight (1.4%) had positive test results (Breast Imaging Reporting and Data System category 0, 3, 4, or 5). All suspicious lesions underwent biopsy and had benign pathologic results. No interval breast cancers were identified. The detection rate for nonpalpable recurrent breast cancer was 0% (exact 95% confidence interval: 0.0%, 1.4%). According to decision analysis, screening would help detect an estimated 12 additional recurrent cancers per 1000 women screened, providing an additional 1.6 days of life expectancy for the screened cohort. Under base-case conditions, screening of TRAM flap reconstructions is less effective than screening asymptomatic women in their 40s. Sensitivity analysis revealed that a benefit equivalent to that of screening asymptomatic women in their 40s was achievable under conditions related to estimates of screening effectiveness and cancer detection rate.

Conclusion: Routine screening mammography of TRAM flap reconstructions has a very low detection rate for nonpalpable recurrent breast cancer. Decision analysis indicates that screening such women is less effective than screening asymptomatic women in their 40s for primary breast cancer.

© RSNA, 2008

Materials and Methods: The institutional review board approved this study, and informed consent was obtained from all subjects. FES and FDG PET studies were performed in 38 patients (mean age, 54.1 years ± 14.0 [standard deviation]) with benign and malignant uterine tumors to compare differences in tracer accumulation. Regional values of tracer uptake were evaluated by using standardized uptake value (SUV), a normalized value corrected by using injection dose and body weight.

Results: Patients with endometrial carcinoma showed significantly greater mean SUV for FDG (9.6 ± 3.3) than for FES (3.8 ± 1.8) (P < .005). Patients with endometrial hyperplasia showed significantly higher mean SUV for FES (7.0 ± 2.9) than for FDG (1.7 ± 0.3) (P < .05). Patients with leiomyoma showed significantly higher mean SUV for FES (4.2 ± 2.4) than for FDG (2.2 ± 1.1) (P < .005), and patients with sarcoma showed opposite tendencies for tracer accumulation. Tracer uptake in patients with endometrial carcinoma was significantly higher for FDG (P < .001) and significantly lower for FES (P < .05) when compared with values in patients with endometrial hyperplasia. On the other hand, patients with sarcoma showed a significantly higher uptake for FDG (P < .005) and a significantly lower uptake for FES (P < .05) compared with patients with leiomyoma.

Conclusion: ER expression and glucose metabolism of uterine tumors measured by using PET showed opposite tendencies. PET studies with both FES and FDG could provide pathophysiologic information for the differential diagnosis of uterine tumors.

© RSNA, 2008

Materials and Methods: The ethics committee approved the study, and patients gave written informed consent. Thirty-four consecutive patients (16 women, 18 men; mean age, 43.2 years) were included who met the following three criteria: They had a focal mass in or adjacent to eloquent cortex of the language or motor system, they had the ability to perform the functional MR imaging task, and they had to undergo surgery with intraoperative ECM. Functional MR imaging with verb generation (n = 17) or finger tapping of the contralateral hand (n = 17) was performed at 1.5 T with a block design and an echo-planar gradient-echo T2*-weighted sequence. Cortex essential for language or hand motor functions was mapped with ECM. A site-by-site comparison between functional MR imaging and ECM was performed with the aid of a neuronavigational device. Sensitivity and specificity were calculated according to task performed, histopathologic findings, and tumor grade. Exact 95% confidence intervals were calculated for each sensitivity and specificity value.

Results: For 34 consecutive patients, there were 28 with gliomas, two with metastases, one with meningioma, and three with cavernous angiomas. A total of 251 cortical sites were tested with ECM; overall functional MR imaging sensitivity and specificity were 83% and 82%, respectively. Sensitivity (65%) was lower and specificity (93%) was higher in World Health Organization grade IV gliomas compared with grade II (sensitivity, 93%; specificity, 79%) and III (sensitivity, 93%; specificity, 76%) gliomas. At 3 months after surgery, language proficiency was unchanged in 15 patients; functionality of the contralateral arm was unchanged in 14 patients and improved in one patient.

Conclusion: Functional MR imaging is a sensitive and specific method for mapping language and motor functions.

© RSNA, 2008

Materials and Methods: Ninety-six polyps were created and analyzed in 14 pig colon phantoms. CT colonography was performed by using a 16-detector CT scanner at 0.75-mm collimation; 10, 50, 100, and 160 mAs; and a pitch of 1.5. At each milliampere-second setting, the CT images were reconstructed with a section thickness (ST) of 1.5 mm and a reconstruction increment (RI) of 1.3 mm. To evaluate the effect of z-axis spatial resolution, CT images were also reconstructed at 100 mAs with various SI and RI combinations (respectively: 1.0 and 0.7 mm, 3.0 and 2.0 mm, 3.0 and 3.0 mm, 5.0 and 5.0 mm). The phantom data were then analyzed by using a CAD program. CAD performance with different CT parameters was calculated and compared in terms of per-polyp sensitivity and number of false-positive (FP) findings per data set.

Results: At a constant tube current of 100 mAs, the polyp detection rate was significantly higher in data sets obtained with SI and RI combinations of 1.0 and 0.7 mm, respectively (81% [78/96]), and 1.5 and 1.3 mm, respectively (75% [72/96]), than in those obtained with the three thicker ST-RI settings (27% [26/96] to 64% [61/96]) (P < .01). A similar trend was observed, regardless of polyp size or morphology. However, the number of FP findings at the 1.0 mm and 0.7 mm setting (8.9 per phantom) was also significantly greater than that at the thicker ST-RI settings (4.0–6.1 per phantom) (P < .05). At a constant z-axis spatial resolution (1.5-mm ST, 1.3-mm RI), CAD polyp detection rate and number of FP findings per phantom remained nearly constant—close to 78% (75/96) and 6.1, respectively—at various tube current settings.

Conclusion: CAD performance in polyp detection at CT colonography is highly dependent on z-axis spatial resolution. However, tube current is not an influencing factor in CAD performance at a given z-axis spatial resolution.

Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2482071025/DC1

© RSNA, 2008

Materials and Methods: The institutional review board approved this HIPAA-compliant study; the need for informed consent was waived. Database review revealed 1655 upper GI studies performed over 6 years in 1282 patients after an RYGB procedure. Leak into the excluded stomach was diagnosed in 48 patients (39 women, nine men; age range, 29–62 years; mean age, 46 years); these patients formed our study group. Studies were analyzed by two radiologists in consensus for extent and pattern of leak into the excluded stomach and the presence of associated complications of extraluminal leak or fistula, obstruction, and acute distention of the excluded stomach. Chart review was performed to determine clinical course, treatment, associated complications, and outcome. Patients were divided into two categories on the basis of acute versus delayed development of leak into the excluded stomach. Acute leak into the excluded stomach was diagnosed within 2 months of surgery. Delayed leak occurred more than 2 months after surgery.

Results: Leak into the excluded stomach occurred in the acute postoperative period (within 2 months) in 25 of the 48 patients (52%) and was associated with extraluminal leak in 22 of those 25 patients (88%). Acute leak into the excluded stomach healed in seven of the 25 patients (28%). Delayed postoperative leak into the excluded stomach occurred in 23 of the 48 patients (48%) and resulted in failed weight loss in 14 of those 23 patients (61%). Fourteen of the 48 patients (29%) underwent surgical revision for leak into the excluded stomach.

Conclusion: Leak into the excluded stomach was identified on upper GI studies in 48 of 1282 patients (3.7%) after RYGB for morbid obesity. Acute leak into the excluded stomach may heal spontaneously; however, remote postoperative leak into the excluded stomach can result in failed weight loss and subsequent failure of the RYGB procedure.

© RSNA, 2008

Materials and Methods: The institutional review board approved this study and waived the requirement for informed consent. Forty male patients aged 62–84 years (mean age, 71 years) who had prostate cancer underwent MR imaging of the prostate gland after ultrasonographically (US) guided systematic 12-core-specimen biopsy. The mean time between biopsy and MR imaging was 24 days (range, 6–54 days). T1-weighted, T2-weighted, dynamic contrast-enhanced, and DW imaging examinations were performed at 1.5 T. The prostate was divided, according to the biopsy sites, into eight regions on the MR images. Three reviewers in consensus evaluated each region for hemorrhage and prostate cancer. Statistical evaluations were performed with Mann-Whitney U, Ryan, and Spearman rank correlation tests.

Results: Intraglandular hemorrhage was observed in 38 (95%) patients and significantly more often in the peripheral zone (PZ) than in the transition zone (TZ) (P < .001). Degree of hemorrhage did not correlate significantly (P = .536) with time between biopsy and MR imaging. The sensitivity, specificity, and accuracy of combined T2-weighted, dynamic contrast-enhanced, and DW imaging in the diagnosis of prostate cancer were 69%, 85%, and 78%, respectively. Sensitivity and specificity were lower for the TZ than for the PZ. Degree of hemorrhage was significantly lower in regions of positive biopsy findings than in regions of negative biopsy findings (P = .001) and correlated negatively with tumor size (P = .043).

Conclusion: Interpretation of combined T2-weighted, dynamic contrast-enhanced, and DW MR image findings can yield reasonable diagnostic accuracy in both the PZ (80% [191 of 240 regions]) and the TZ (74% [59 of 80 regions]).

© RSNA, 2008

Materials and Methods: The study protocol was approved by the institutional review board, and all patients gave written informed consent. One hundred eighty-one patients (79 men, 102 women; age range, 36–85 years) underwent ultrasonographically (US) guided percutaneous RF ablation of 361 primary or secondary (metastatic) liver tumors. Forty-four patients had one or more subcapsular nodules (group 1), and 137 had nonsubcapsular nodules only (group 2). Overall, 80 nodules were subcapsular and 281 were nonsubcapsular. The completeness of the ablation was assessed with contrast material–enhanced computed tomography (CT) 1 month after RF ablation. If residual tumor was documented, RF ablation was repeated. All patients in whom the ablation was complete after the first or second ablation session were monitored with CT or contrast-enhanced US every 3 months. Major complication, complete ablation, and local tumor progression rates were compared by using the ² test or Fisher exact test.

Results: Three (7%) major complications (intraperitoneal bleeding, skin burn, and tumor seeding) occurred in group 1, and two (1.5%) cases of tumor seeding occurred in group 2 (P = .093). No RF ablation–related deaths occurred. The complete ablation rate was 98% (43 of 44 patients) in group 1 and 98.5% (135 of 137 patients) in group 2 (P = .756). The local tumor progression rate after a median follow-up of 25 months (range, 13–54 months) was 16% (seven of 43 patients) in group 1 and 9.6% (13 of 135 patients) in group 2 (P = .355).

Conclusion: The difference in major complication rate between the subcapsular and nonsubcapsular liver tumors was not significant. The safety of RF ablation of subcapsular tumors seems acceptable, and the effectiveness is comparable to that of RF ablation of nonsubcapsular tumors.

© RSNA, 2008

Materials and Methods: Institutional review board approval and waiver of informed consent were obtained for this HIPAA–compliant study; 121 patients with ovarian cancer (age range, 29–94 years; mean age, 57.8 years) formed the study group. Two radiologists blinded to patient clinical data (radiologist 1, 6 months of experience; radiologist 2, 2 years 6 months of experience) retrospectively and independently recorded presence of perihepatic metastases, liver regions involved, and presence of LPI by perihepatic metastases visible on CT images. Sensitivities and specificities for detecting the presence of perihepatic metastases and liver regions involved and sensitivities for detecting LPI were calculated. Statistics were used to analyze interradiologist agreement.

Results: Pathologic examination results showed 66 perihepatic metastases in 43 (36%) of 121 patients. Sixty (91%) of 66 perihepatic metastases did not show signs of LPI and six (9%) did. Sensitivity and specificity combinations for radiologists 1 and 2 were 56% and 87% and 86% and 99%, respectively, for detecting the presence of perihepatic metastases and 46% and 97% and 82% and 100%, respectively, for determining liver regions involved. Radiologists 1 and 2 had sensitivities of 35% and 80%, respectively, for detecting regions with perihepatic metastases without LPI and sensitivities of 50% and 100%, respectively, for detecting regions with perihepatic metastases with LPI.

Conclusion: CT can be used to detect perihepatic metastases in patients with ovarian cancer and allows for distinction between metastases that invade the liver and those that do not.

© RSNA, 2008