Faculty Bibliography

To determine the added value of reimaging the female pelvis with ultrasound (US) immediately following multidetector CT (MDCT) in the emergent setting. CT and US exams of 70 patients who underwent MDCT for evaluation of abdominal/pelvic pain followed by pelvic ultrasound within 48 h were retrospectively reviewed by three readers. Initially, only the CT images were reviewed followed by evaluation of CT images in conjunction with US images. Diagnostic confidence was recorded for each reading and an exact Wilcoxon signed rank test was performed to compare the two. Changes in diagnosis based on combined CT and US readings versus CT readings alone were identified. Confidence intervals (95%) were derived for the percentage of times US reimaging can be expected to lead to a change in diagnosis relative to the diagnosis based on CT interpretation alone. Ultrasound changed the diagnosis for the ovaries/adnexa 8.1% of the time (three reader average); the majority being cases of a suspected CT abnormality found to be normal on US. Ultrasound changed the diagnosis for the uterus 11.9% of the time (three reader average); the majority related to the endometrial canal. The 95% confidence intervals for the ovaries/adnexa and uterus were 5-12.5% and 8-17%, respectively. Ten cases of a normal CT were followed by a normal US with 100% agreement across all three readers. Experienced readers correctly diagnosed ruptured ovarian cysts and tubo-ovarian abscesses (TOA) based on CT alone with 100% agreement. US reimaging after MDCT of the abdomen and pelvis is not helpful: (1) following a normal CT of the pelvic organs or (2) when CT findings are diagnostic and/or characteristic of certain entities such as ruptured cysts and TOA. Reimaging with ultrasound is warranted for (1) less-experienced readers to improve diagnostic confidence or when CT findings are not definitive, (2) further evaluation of suspected endometrial abnormalities. A distinction should be made between the need for immediate vs. follow-up imaging with US after CT

PURPOSE: To assess the accuracy of glomerular filtration rate (GFR) measurements obtained with low-contrast agent dose dynamic contrast material-enhanced magnetic resonance (MR) renography in patients with liver cirrhosis who underwent routine liver MR imaging, with urinary clearance of technetium 99m ((99m)Tc) pentetic acid (DTPA) as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved. Written informed patient consent was obtained. Twenty patients with cirrhosis (14 men, six women; age range, 41-70 years; mean age, 54.6 years) who were scheduled for routine 1.5-T liver MR examinations to screen for hepatocellular carcinoma during a 6-month period were prospectively included. Five-minute MR renography with a 3-mL dose of gadoteridol was performed instead of a routine test-dose timing examination. The GFR was estimated at MR imaging with use of two kinetic models. In one model, only the signal intensities in the aorta and kidney parenchyma were considered, and in the other, renal cortical and medullary signal intensities were treated separately. The GFR was also calculated by using serum creatinine levels according to the Cockcroft-Gault and modification of diet in renal disease (MDRD) formulas. All patients underwent a (99m)Tc-DTPA urinary clearance examination on the same day to obtain a reference GFR measurement. The accuracies of all MR- and creatinine-based GFR estimations were compared by using Wilcoxon signed rank tests. RESULTS: The mean reference GFR, based on (99m)Tc-DTPA clearance, was 74.9 mL/min/1.73 m(2) +/- 27.7 (standard deviation) (range, 10.3-120.7 mL/min/1.73 m(2)). With both kinetic models, 95% of MR-based GFRs were within 30% of the reference values, whereas only 40% and 60% of Cockcroft-Gault- and MDRD-based GFRs, respectively, were within this range. MR-based GFR estimates were significantly more accurate than creatinine level-based estimates (P < .001). CONCLUSION: GFR assessment with MR imaging, which outperformed the Cockcroft-Gault and MDRD formulas, adds less than 10 minutes of table time to a clinically indicated liver MR examination without ionizing radiation. Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101338/-/DC1

OBJECTIVE: The purpose of this article is to compare 3D T2-weighted sampling perfection with application-optimized contrast with different flip-angle evolutions (SPACE) with three-plane 2D turbo-spin echo (TSE) sequences for female pelvic imaging at 3 T. MATERIALS AND METHODS: Twenty women were imaged with 2D TSE and 3D SPACE sequences. Three radiologists independently assessed image quality, diagnostic quality, and artifacts; measured normal anatomic structures; evaluated pathologic abnormalities; and recorded interpretation time. Readers subsequently performed a side-by-side comparison, and their preferences were graded according to overall interpretation, sharpness of lesion edges, motion and other artifacts, uterine and cervical zonal anatomy distinction, identification of adnexal pathologic abnormalities, and distinction between fat and fluid. Quantitative comparison of relative signal intensity and relative tissue contrast was performed. RESULTS: The mean acquisition time of 3D SPACE was significantly shorter than that of 2D TSE (6 minutes 35 seconds vs 8 minutes 50 seconds; p < 0.005). Intrareader agreement between interpretations of 2D and 3D sequences was excellent. There were no significant differences among readers in detecting artifacts, normal structures, and pathologic abnormalities or in determining endometrial thickness, image quality, or interpretation time (p > 0.05). Except for distinctions between fat and fluid, the average reader score indicated a slight preference for the 3D sequence. Three-dimensional multiplanar reconstructions were helpful but not considered essential. Relative agreement between readers was moderate (r >/= 0.4) to strong (r >/= 0.7). The relative signal intensity was higher for fat and bladder fluid on the 3D sequence than on the 2D sequence (p = 0.014 and p = 0.018, respectively). Relative tissue contrast was higher for the 3D sequence (p < 0.05), with no significant difference in bladder or fat contrast (p = 0.31) but a trend toward more superior contrast on the 2D sequence. CONCLUSION: At 3 T, 3D SPACE has similar image quality and diagnostic quality with shorter scan time when compared with 2D TSE but with reduced contrast between fat and fluid

PURPOSE: To determine whether inhibition of TGFbeta signaling prior to irradiation sensitizes human and murine cancer cells in vitro and in vivo. EXPERIMENTAL DESIGN: TGFbeta-mediated growth and Smad phosphorylation of MCF7, Hs578T, MDA-MB-231, and T47D human breast cancer cell lines were examined and correlated with clonogenic survival following graded radiation doses with and without pretreatment with LY364947, a small molecule inhibitor of the TGFbeta type I receptor kinase. The DNA damage response was assessed in irradiated MDA-MB-231 cells pretreated with LY364947 in vitro and LY2109761, a pharmacokinetically stable inhibitor of TGFbeta signaling, in vivo. The in vitro response of a syngeneic murine tumor, 4T1, was tested using a TGFbeta neutralizing antibody, 1D11, with single or fractionated radiation doses in vivo. RESULTS: Human breast cancer cell lines pretreated with TGFbeta small molecule inhibitor were radiosensitized, irrespective of sensitivity to TGFbeta growth inhibition. Consistent with increased clonogenic cell death, radiation-induced phosphorylation of H2AX and p53 was significantly reduced in MDA-MB-231 triple-negative breast cancer cells when pretreated in vitro or in vivo with a TGFbeta type I receptor kinase inhibitor. Moreover, TGFbeta neutralizing antibodies increased radiation sensitivity, blocked gammaH2AX foci formation, and significantly increased tumor growth delay in 4T1 murine mammary tumors in response to single and fractionated radiation exposures. CONCLUSION: These results show that TGFbeta inhibition prior to radiation attenuated DNA damage responses, increased clonogenic cell death, and promoted tumor growth delay, and thus may be an effective adjunct in cancer radiotherapy. Clin Cancer Res; 17(21); 6754-65. (c)2011 AACR

OBJECTIVE:: To compare free-breathing radially sampled 3D fat suppressed T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with breath-hold (BH) and free-breathing conventional (rectilinearly sampled k-space) VIBE acquisitions for postcontrast imaging of the liver. MATERIALS AND METHODS:: Eighteen consecutive patients referred for clinically indicated liver magnetic resonance imaging were imaged at 3 T. Three minutes after a single dose of gadolinium contrast injection, free-breathing radial VIBE, BH VIBE, and free-breathing VIBE with 4 averages were acquired in random order with matching sequence parameters. Radial VIBE was acquired with the 'stack-of-stars' scheme, which uses conventional sampling in the slice direction and radial sampling in-plane.All image data sets were evaluated independently by 3 radiologists blinded to patient and sequence information. Each reader scored the following parameters: overall image quality, respiratory motion artifact, pulsation artifact, liver edge sharpness, and hepatic vessel clarity using a 5-point scale, with the highest score indicating the most optimum examination. Mixed model analysis of variance was used to compare sequences in terms of each measure of image quality. RESULTS:: When scores were averaged over readers, there was no statistically significant difference between radial VIBE and BH VIBE regarding overall image quality (P = 0.1015), respiratory motion artifact (P = 1.0), and liver edge sharpness (P = 0.2955). Radial VIBE demonstrated significantly lower pulsation artifact (P < 0.0001), but had lower hepatic vessel clarity (P = 0.0176), when compared with BH VIBE. Radial VIBE had significantly higher image quality scores for all parameters when compared with free-breathing VIBE (P < 0.0001). Acquisition time for BH VIBE was 14 seconds and that of free-breathing radial VIBE and conventional VIBE with multiple averages was 56 seconds each. CONCLUSION:: Radial VIBE can be performed during free breathing for contrast-enhanced imaging of the liver with comparable image quality to BH VIBE. However, further work is necessary to shorten the acquisition time to perform dynamic imaging

AIM: To determine whether the location of the computed tomography (CT) whirl sign can be used to help differentiate caecal from sigmoid volvulus. MATERIALS AND METHODS: Thirty-one patients (mean age 64.6 years) underwent multidetector CT and had confirmed colonic volvulus. There were 15 patients with caecal volvulus and 16 with sigmoid volvulus. Axial and coronal images were retrospectively evaluated on the picture archiving and communication system (PACS) by two reviewers in consensus without knowledge of the final diagnosis to determine whether a CT whirl sign was present and, if so, was the location to the right of midline or in the midline/left. The location of the twisting at imaging was correlated with whether the patient had caecal or sigmoid volvulus. Fisher's exact test was used to determine whether there was an association between the location of the twist (right versus mid-left) and the location of the colonic volvulus (caecal versus sigmoid). The non contrast CT (NCCT) examinations of 30 additional patients without colonic volvulus were evaluated for the presence or absence of a CT whirl sign. RESULTS: All 31 patients with colonic volvulus had a CT whirl sign. No patient who underwent NCCT for kidney stones demonstrated a CT whirl sign. According to Fisher's exact test, there was a highly significant association (p<0.0001) between the location of the twist (right versus mid-left) and the location of the colonic volvulus (caecal versus sigmoid). Using the location of the twist as a predictor of whether the volvulus was caecal or sigmoid provided a correct diagnosis for 93.3% (14/15) of the patients with caecal volvulus and 100% (16/16) of those with sigmoid volvulus, yielding an overall diagnostic accuracy of 96.8% (30/31). CONCLUSION: The location of the mesenteric twist (CT whirl sign) is a highly accurate finding in discriminating caecal from sigmoid volvulus

OBJECT: The goal of this study was to determine the feasibility of performing quantitative 7 T magnetic resonance imaging (MRI) assessment of trabecular bone micro-architecture of the wrist, a common fracture site. MATERIALS AND METHODS: The wrists of 4 healthy subjects (1 woman, 3 men, 28+/-8.9 years) were scanned on a 7 T whole body MR scanner using a 3D fast low-angle shot (FLASH) sequence (TR/TE = 20/4.5 m s, 0.169x0.169x0.5 mm). Trabecular bone was segmented and divided into 4 or 8 angular subregions. Total bone volume (TBV), bone volume fraction (BVF), surface-curve ratio (SC), and erosion index (EI) were computed. Subjects were scanned twice to assess measurement reproducibility. RESULTS: Group mean subregional values for TBV, BVF, SC, and EI (8 subregion analysis) were as follows: 8489 +/- 3686, 0.27 +/- 0.045, 9.61 +/- 6.52; and 1.43 +/- 1.25. Within each individual, there was subregional variation in TBV, SC, and EI (>5%), but not BVF (<5%). Intersubject variation (>/=12%) existed for all parameters. Within-subject coefficients of variation were </=10%. CONCLUSION: This is the first study to perform quantitative 7T MRI assessment of trabecular bone micro-architecture of the wrist. This method could be utilized to study perturbations in bone structure in subjects with osteoporosis or other bone disorders

BACKGROUND AND PURPOSE: Although NAA is often used as a marker of neural integrity and health in different neurologic disorders, the temporal behavior of WBNAA is not well characterized. Our goal therefore was to establish its normal variations in a cohort of healthy adults over typical clinical trial periods. MATERIALS AND METHODS: Baseline amount of brain NAA, Q(NAA), was obtained with nonlocalizing proton MR spectroscopy from 9 subjects (7 women, 2 men; 31.2 +/- 5.6 years old). Q(NAA) was converted into absolute millimole amount by using phantom-replacement. The WBNAA concentration was derived by dividing Q(NAA) with the brain parenchyma volume, V(B), segmented from MR imaging. Temporal variations were determined with 4 annual scans of each participant. RESULTS: The distribution of WBNAA levels was not different among time points with respect to the mean, 12.1 +/- 1.5 mmol/L (P > .6), nor was its intrasubject change (coefficient of variation = 8.6%) significant between any 2 scans (P > .5). There was a small (0.2 mL) but significant (P = .05) annual V(B) decline. CONCLUSIONS: WBNAA is stable over a 3-year period in healthy adults. It qualifies therefore as a biomarker for global neuronal loss and dysfunction in diffuse neurologic disorders that may be well worth considering as a secondary outcome measure candidate for clinical trials

PURPOSE: To retrospectively assess the utility of fusion of T2-weighted images (T2WI) and high b-value diffusion-weighted images (DWI) for prostate cancer detection and localization. MATERIALS AND METHODS: In this IRB-approved HIPAA-compliant study, 42 patients with prostate cancer underwent MRI including multiplanar T2WI and axial DWI before prostatectomy. Two independent radiologists first assessed multiplanar T2WI and axial DWI(b-1000) images and recorded whether tumor was present in each sextant. Axial T2WI was then fused with axial DWI(b-1000) images, and the radiologists re-evaluated each sextant for tumor. Accuracy was compared using generalized estimating equations based on a binary logistic regression model. RESULTS: The accuracy, sensitivity, specificity, PPV, and NPV for tumor detection on a sextant-basis using separate and fused image sets was 65.1%, 50.8%, 78.0%, 67.8%, and 63.6% and 71.0%, 60.8%, 80.3%, 73.7%, and 69.3%, respectively, for reader 1, and 54.0%, 42.5%, 64.4%, 52.0%, and 55.2%, and 61.1%, 56.7%, 65.2%, 59.6%, and 62.3%, respectively, for reader 2. The improvements in accuracy, sensitivity, and NPV using fused images were statistically significant for both readers, as was the improvement in PPV for reader 2 (P ranging from <0.0001 to 0.041). With either separate or fused images, there was greater sensitivity for tumors of higher grade or larger size (P ranging from <0.001 to 0.099). CONCLUSION: Fusion of T2WI and high b-value DWI resulted in significant improvements in sensitivity and accuracy for tumor detection on a sextant-basis, with similar specificity. J. Magn. Reson. Imaging 2011;. (c) 2011 Wiley-Liss, Inc