Faculty Bibliography

Prostate cancer treatment is a controversial topic amongst physicians and patients alike. Radical therapies such as prostatectomy and whole gland radiation offer the best outcomes in terms of oncologic efficacy, but the decision to undergo treatment must be weighed against its potential morbidity. Over the past decade, the concept of focal therapy for prostate cancer has been introduced as a potential method of achieving oncologic control with a lesser degree of morbidity. Focal therapy refers to isolated ablation of a tumor focus with sparing of uninvolved, surrounding tissue. While it remains in the early stages of development, considerable research is underway that will help determine the optimal method of achieving this goal. Current areas of investigation include appropriate candidate selection, lesion identification, modality of treatment, and follow-up strategies

OBJECTIVE: The purpose of this article is to review the roles that MRI is expected to play in emerging minimally invasive focal ablative therapies for prostate cancer. CONCLUSION: MRI, in combination with biopsy, will impact patient selection for focal ablation by helping to localize clinically significant tumor foci. Also, some ablation procedures may be performed using real-time MRI guidance. In addition, MRI may be used for assessment of extent of necrosis shortly after therapy and for long-term surveillance for recurrent tumor

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

AIM: To compare image quality and lesion detection in the liver using magnetic resonance imaging (MRI) at 3T between T2-weighted imaging using a standard rectilinear k-space trajectory (standard T2WI) and using the BLADE technique (BLADE-T2WI), a technique that employs periodically rotated overlapping parallel lines with enhanced reconstruction for motion correction. MATERIALS AND METHODS: Twenty-eight consecutive patients who underwent MRI examination of the liver at 3T including standard T2WI and BLADE-T2WI, both performed using multiple breath-holds, comprised the study cohort. Images were reviewed in consensus by two radiologists during separate sessions for a number of measures regarding artefacts and image quality. These two readers also assessed the two image sets for the presence of liver lesions and measured liver-to-lesion contrast. Binary logistic regression for correlated data was used to compare the sequences in terms of sensitivity and positive predictive value (PPV) for lesion detection. RESULTS: BLADE-T2WI received significantly higher scores than did standard T2WI for in-plane respiratory motion (p=0.0195), other ghosting artefacts (p<0.0001), sharpness of the liver edge (p=0.0004), sharpness of intra-hepatic vessels (p<0.0001), flow signal suppression (p<0.0001), and overall image quality (p<0.0001). There was a non-significant trend toward improved B(1)-inhomogeneity artefact with BLADE-T2WI (p=0.0571). There was no difference in through-plane respiratory motion (p=0.6836). BLADE-T2WI demonstrated a significant improvement in PPV for lesion detection (p=0.0129) as well as in liver-to-lesion contrast (p=0.0054). There was no difference regarding lesion sensitivity (p=1.0). CONCLUSIONS: Use of the BLADE technique for T2-weighted MRI of the liver at 3T may lead to a significant improvement in image artefacts and improved PPV for lesion detection

OBJECTIVE: The purpose of this study was to assess the possible clinical significance of bladder urine T1 hyperintensity based upon comparison with urinalysis findings, using a cohort of patients who underwent prostate MRI and urinalysis at a similar point in time during preoperative work-up. METHODS: We identified 56 patients who underwent prostatectomy at our institution who obtained prostate MRI and urinalysis within 1 day of each other preoperatively. A control group of 160 consecutive adult men who underwent pelvic MRI during the same time period for other indications was also identified. Two radiologists independently and in consensus reviewed the T1-weighted images to assess the frequency of bladder urine T1 hyperintensity in both groups. The urinalyses in the 56 men undergoing prostatectomy were reviewed, with the results compared between patients with and without bladder urine T1 hyperintensity. RESULTS: Four (7.1%) of 56 men with prostate cancer exhibited T1 hyperintense bladder urine, compared with six (3.8%) of 160 patients exhibiting this finding in the control group (P=.288). Of the four prostate cancer patients with this finding, all exhibited a normal urinalysis. An abnormal urinalysis was identified for four of the prostate cancer patients, all of whom exhibited normal urine T1 signal intensity. CONCLUSION: Bladder urine T1 hyperintensity may be seen occasionally in patients with prostate cancer but is not associated with abnormal urinalysis and therefore should not be regarded as a sign of acute urinary pathology

Renal replacement lipomatosis is a rare benign entity in which extensive fibrofatty proliferation of the renal sinus is associated with marked renal atrophy. In this report, we present a case of massive renal replacement lipomatosis demonstrated on MRI. The presentation was atypical given an absence of associated renal calculus disease, and an initial CT scan was interpreted as suspicious for a liposarcoma. The differential diagnosis and key MRI findings that served to establish this specific diagnosis are reviewed. Histopathological correlation is also presented, as the patient underwent nephroureterectomy

PURPOSE: : To compare image quality and lesion detection in postcontrast liver magnetic resonance imaging (MRI) between volumetric interpolated breath-hold examination (VIBE) sequences that achieve fat suppression via chemically selective fat saturation (FS-VIBE) and a 2-point Dixon water-fat separation method (Dixon-VIBE). MATERIALS AND METHODS: : Thirty patients underwent contrast-enhanced liver MRI at 1.5 T in which Dixon-VIBE was performed immediately after a delayed FS-VIBE. Two radiologists in consensus reviewed the sequences for a variety of qualitative and quantitative image quality measures and for lesion detection. RESULTS: : Dixon-VIBE received nearly perfect scores for strength and homogeneity of fat suppression that were significantly better than scores for FS-VIBE, with an associated significant improvement in liver-fat contrast (P < 0.0001 for all comparisons). Dixon-VIBE also received significantly better scores for sharpness of intrahepatic vessels (P = 0.0029) and overall image quality (P < 0.0001). Despite a slightly longer acquisition time for Dixon-VIBE, there was no significant difference in motion artifact (P = 0.3877). There was no significant difference for sensitivity, positive predictive value, or contrast relative to background liver for focal lesions (P = 0.448, P = 0.347, and P = 0.2312, respectively). CONCLUSIONS: : For postcontrast liver MRI, Dixon-VIBE demonstrated significantly improved fat suppression. Various assessments of lesion detection showed no significant difference between sequences

OBJECTIVE: The purpose of our study was to compare the visibility of prostate cancer on trace diffusion-weighted (DW) images and the apparent diffusion coefficient (ADC) map. MATERIALS AND METHODS: In this retrospective study, 45 patients with prostate cancer underwent preoperative MRI, including DW imaging (DWI) (b values 0, 500, and 1,000 s/mm(2)). A single observer reviewed the images in conjunction with tumor maps constructed from prostatectomy. For 132 peripheral zone (PZ) tumor foci, the visibility and contrast relative to benign PZ were recorded for T2-weighted imaging, trace DWI b500 images, trace DWI b1,000 images, and ADC maps. Trace DWI b1,000 images and ADC maps were compared in terms of Gleason score, size, normalized T2 signal intensity, ADC, and normalized ADC of visible tumors. RESULTS: For each image set, the percentage of visible tumor foci and contrast relative to benign PZ were as follows: T2-weighted imaging, 80.3% and 0.411; trace DWI b500, 26.5% and 0.131; trace DWI b1,000, 46.2% and 0.119; and ADC maps, 62.1% and 0.309. Forty-seven tumor foci were visible on both trace DWI b1,000 images and ADC maps, 14 only on trace DWI b1,000 images, 35 only on ADC maps, and 36 on neither image set. There was no significant difference in Gleason score, size, normalized T2 signal intensity, ADC, or normalized ADC between tumors visible only on trace DWI b1,000 images and those visible only on ADC maps. CONCLUSION: Given a greater proportion of tumors visible on the ADC map than trace DWI and greater contrast relative to benign PZ on the ADC map, we suggest that, when performing DWI of the prostate, careful attention be given to the ADC map for tumor identification

PURPOSE: To compare single-shot echo-planar imaging (SS EPI) diffusion-weighted MRI (DWI) of abdominal organs between 1.5 Tesla (T) and 3.0T in healthy volunteers in terms of image quality, apparent diffusion coefficient (ADC) values, and ADC reproducibility. MATERIALS AND METHODS: Eight healthy volunteers were prospectively imaged in this HIPAA-compliant IRB-approved study. Each subject underwent two consecutive scans at both 1.5 and 3.0T, which included breathhold and free-breathing DWI using a wide range of b-values (0 to 800 s/mm(2) ). A blinded observer rated subjective image quality (maximum score= 8), and a separate observer placed regions of interest within the liver, renal cortices, pancreas, and spleen to measure ADC at each field strength. Paired Wilcoxon tests were used to compare abdominal DWI between 1.5T and 3.0T for specific combinations of organs, b-values, and acquisition techniques. RESULTS: Subjective image quality was significantly lower at 3.0T for all comparisons (P = 0.0078- 0.0156). ADC values were similar at 1.5T and 3.0T for all assessed organs, except for lower liver ADC at 3.0T using b0-500-600 and breathhold technique. ADC reproducibility was moderate at both 1.5T and 3.0T, with no significant difference in coefficient of variation of ADC between field strengths. CONCLUSION: Compared with 1.5T, SS EPI at 3.0T provided generally similar ADC values, however, with worse image quality. Further optimization of abdominal DWI at 3.0T is needed. J. Magn. Reson. Imaging 2011;33:128-135. (c) 2010 Wiley-Liss, Inc