Faculty Bibliography

PURPOSE/OBJECTIVE:To evaluate the role of conventional endorectal prostate MRI in patients with initial suspicion of prostate cancer. MATERIALS AND METHODS/METHODS:Ethics board approval was received for this retrospective study of 87 men who underwent 1.5-Tesla conventional prostate MRI with a combination of endorectal and body phased-array coils for suspected prostate cancer before their first systematic 12-core TRUS-guided biopsy. Three radiologists independently analyzed the images, dividing the prostate into 12 regions corresponding to the biopsy scheme and scoring each region for the presence of prostate cancer on a 5-point scale. Results were analyzed by prostate region. ROC analysis was done and descriptive statistics were calculated. The negative predictive value, specificity, sensitivity and positive predictive value were calculated using dichotomized scores (benign tissue = scores of 1 and 2; malignant tissues = scores of 3, 4, and 5). RESULTS:Biopsy revealed cancer in 47/87 patients (26 low-grade [Gleason score 6]; 21 high-grade [Gleason score ≥ 3 + 4]), and 184/1044 cores (77 low-grade and 107 high-grade) with a median of 3 positive cores per cancer patient (range 1 - 12). The areas under ROC curves were 0.65 - 0.67 for cancer detection by region overall and 0.75 - 0.76 for the detection of high-grade cancer by region. Statistic figures for the detection of all cancers/high-grade cancers by region were as follows: negative predictive value, 87.4 - 88.2 %/92.6 - 93.1 %; specificity, 72.3 - 79.4 %/71.5 - 79.8 %; sensitivity, 49.5 - 54.8 %/62.6 - 69.2 %; and positive predictive value, 29.3 - 34.0 %/29.4 - 34.7 %. CONCLUSION/CONCLUSIONS:In patients with suspected prostate cancer, negative MRI findings indicate the absence of high-grade prostate cancer on subsequent TRUS-guided 12-core biopsy with high probability. However, agreement between conventional 1.5-T endorectal prostate MRI and systematic 12-core TRUS-guided biopsy for the detection of prostate cancer appears to be moderate.

OBJECTIVE:Pelvic radiation therapy (RT) can influence fertility in female rectal cancer survivors. Data regarding its effects on the adult uterus are scant. This study aims to evaluate the uterus before and after RT, using dynamic contrast-enhanced MRI. METHODS:Eligible patients (n=10) received RT for rectal cancer, had an intact uterus and underwent dynamic contrast-enhanced MRI before and after RT. Seven patients were pre-menopausal. RESULTS:Patients received pelvic RT (median, 50.2 Gy) with concurrent 5-fluorouracil. Five patients were treated with intensity modulated RT (IMRT) and five with a three-field technique. The median D95 of the uterus was 30 Gy; D05 was 48 Gy; and V95 was 97%. The median cervical D95 was 45 Gy; D05, 50 Gy; and V95, 100%. Cervical dose was higher with IMRT than with three-field plans (p≤0.038). On T2 MRI, the junctional zone was visible in nine patients before and in one after RT (p=0.001). Median cervical length (2.3 vs 3.0 cm) and endometrial thickness (2.6 vs 5.9 mm) were reduced after RT (p≤0.008). In pre-menopausal patients, the volume transfer constant, K(trans), (0.069 vs 0.195, p=0.006) and the extracellular extravascular volume fraction, V(e), (0.217 vs 0.520, p=0.053) decreased. CONCLUSION/CONCLUSIONS:Pelvic RT significantly affected uterine anatomy and perfusion. Cervical dose was higher with IMRT than three-field plans, but no attempt was made to constrain the dose. ADVANCES IN KNOWLEDGE/CONCLUSIONS:Pelvic RT significantly affects the adult uterus. These findings are crucial to understand the potential consequences of RT on fertility, and they lay the groundwork for further prospective studies.

PURPOSE/OBJECTIVE:To assess radiotherapy (RT)-induced changes in the urethra and periurethral tissues after treatment for prostate cancer (PCa). METHODS AND MATERIALS/METHODS:This retrospective study included 108 men (median age, 64 years; range, 43-87 years) who received external-beam radiotherapy (EBRT) and/or brachytherapy for PCa and underwent endorectal-coil MRI of the prostate within 180 days before RT and a median of 20 months (range, 2-62 months) after RT. On all MRIs, two readers independently measured the urethral length (UL) and graded the margin definition (MD) of the urethral wall and the signal intensities (SIs) of the urethral wall and pelvic muscles on 4-point scales. RESULTS:The mean urethral length decreased significantly from pre- to post-RT MRI (from 15.2 to 12.6mm and from 14.4 to 12.9 mm for readers 1 and 2, respectively; both p-values <0.0001). Brachytherapy resulted in greater urethral shortening than EBRT. After RT, SI in the urethral wall increased in 57% (62/108) and 35% (38/108) of patients (readers 1 and 2, respectively). The frequency and magnitude of SI increase in pelvic muscles depended on muscle location. In the obturator internus muscle, SI increased more often after EBRT than after brachytherapy, while in the periurethral levator ani muscle SI increased more often after brachytherapy than after EBRT. CONCLUSION/CONCLUSIONS:After RT for PCa, MRI shows urethral shortening and increased SI of the urethral wall and pelvic muscles in substantial percentages of patients.

OBJECTIVE:Magnetic resonance imaging (MRI) is the modality of choice for staging gynecological cancers owing to its superb soft tissue resolution, whereas F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) allows the assessment of glycolytic activity within the tumor microenvironment. In this study, we evaluated the incremental value of fused MRI/PET over MRI or fluorodeoxyglucose PET/CT alone for assessing local disease extent in patients with recurrent gynecological cancers undergoing pelvic exenteration and determined the associations between imaging findings and clinical outcomes in this patient population. MATERIALS AND METHODS/METHODS:The institutional review board approved this retrospective, Health Insurance Portability and Accountability Act (HIPAA)-compliant study of 31 patients who underwent pelvic MRI and PET/CT 3 months or less before pelvic exenteration for recurrent cancers of the uterine cervix, corpus, or vulva/vagina. Using a 1 to 5 scale (1, definitely not present; 5, definitely present), 2 readers independently evaluated MRI, PET/CT, and fused MRI/PET images for the presence of bladder, rectum, and pelvic sidewall invasion. Surgical pathology constituted the reference standard. Measurements of diagnostic accuracy, interreader agreement, and associations between imaging findings and progression-free survival and overall survival were calculated. RESULTS:Compared with MRI or PET/CT, fused MRI/PET correctly improved readers' diagnostic confidence in detecting bladder, rectum, or pelvic sidewall invasion in up to 52% of patients. Interreader agreement was consistently in the highest ("almost perfect") range only for MRI/PET (κ = 0.84-1.0). The highest sensitivities (0.82-1.0), specificities (0.91-1.0), and predictive values (0.80-1.0) were consistently achieved with fused MRI/PET (although the differences were not statistically significant [P > 0.05]). Pelvic sidewall invasion on MRI/PET was the only finding significantly associated with both progression-free and overall survival for both readers (P = 0.0067-0.0440). CONCLUSIONS:In patients with recurrent gynecological cancers undergoing pelvic exenteration, fused MRI/PET served as a predictive biomarker and yielded greater diagnostic confidence and interreader agreement than either MRI or PET/CT.

A 52-year-old woman with metastatic melanoma was treated with ipilimumab. After 2 cycles of treatment, she developed watery diarrhea, sweats, and chills. An FDG PET/CT study demonstrated new FDG-avid (maximum standardized uptake value 15.6) diffuse colonic wall thickening, suggestive of ipilimumab-induced colitis. The patient was treated with systemic steroids, with subsequent resolution of her symptoms. Based on the response to steroids, the diagnosis of ipilimumab-induced enterocolitis was made. Ipilimumab may cause several immune-mediated toxicities, the most common of which is enterocolitis. Physicians interpreting FDG PET/CT examinations of patients treated with ipilimumab should be aware of these FDG-avid immune-mediated toxicities.

PURPOSE/OBJECTIVE:To compare the accuracy of standard and revised monoexponential models of diffusion-weighted magnetic resonance imaging (DW-MRI) data for differentiating malignant from benign prostate tissue, using surgical pathology as the reference standard. MATERIALS AND METHODS/METHODS:The Institutional Review Board waived informed consent for this Health Insurance Portability and Accountability Act (HIPAA)-compliant, retrospective study of 46 patients (median age = 61 years; range: 42-85 years) who underwent DW-MRI between May and December 2008 before radical prostatectomy for biopsy-proven prostate cancer, had no prior treatment, and had whole-mount step-section pathology maps available showing at least one peripheral zone (PZ) lesion >0.1 cm(3) . DW-MRI data were obtained for b-values of 0, 400, and 700 s/mm(2) . Apparent diffusion coefficients (ADCs) were estimated from PZ regions of interest (ROIs) on b = 0, 700 and b = 0, 400 s/mm(2) images, using a standard monoexponential model. The true diffusion coefficient (D) and perfusion fraction (f) were measured using a revised monoexponential model incorporating all three b-values. Areas under receiver operating characteristic curves (AUCs) were calculated to assess the accuracy of individual parameters and a logistic regression model combining D and f (D+f) in distinguishing malignant ROIs; P < 0.05 denoted significance. RESULTS:ADC(400) (AUC = 0.81, P < 0.0001), ADC(700) (AUC = 0.79, P < 0.0001), D (AUC = 0.71, P = 0.0001) and D + f distinguished malignant from benign ROIs (AUC = 0.82, P < 0.0001), but f did not (AUC = 0.56, P = 0.28); D + f was significantly more accurate than D (P = 0.016) but not more accurate than ADC(400) (P = 0.26) or ADC(700) (P = 0.12). CONCLUSION/CONCLUSIONS:The true diffusion coefficient provides an additional DW-MRI parameter for distinguishing prostate cancer that is less influenced than the ADC by b-value selection.

Many management options are available to patients with newly diagnosed prostate cancer. Magnetic resonance (MR) imaging plays an important role in initial staging of prostate cancer, but it also aids in tumor detection when there is clinical or biochemical suspicion of residual or recurrent disease after treatment. The purpose of this review is to describe the normal appearances of the prostatic region after different kinds of treatment for prostate cancer and to discuss how these appearances differ from those of recurrent and residual disease. Several MR imaging techniques used in evaluating patients with prostate cancer are described, including conventional MR imaging sequences (mainly T1- and T2-weighted sequences), MR spectroscopic imaging, diffusion-weighted imaging, and dynamic contrast agent-enhanced MR imaging. Clinical considerations, together with the different approaches for interpreting serum prostate-specific antigen values in the posttreatment setting, are also presented. All forms of treatment alter the MR imaging features of the prostatic region to a greater or lesser extent, and it is important to be able to recognize expected posttreatment appearances and distinguish them from the features of recurrent or residual cancer to aid subsequent clinical management.

PURPOSE/OBJECTIVE:To describe the anatomic features of the central zone of the prostate on T2-weighted and diffusion-weighted (DW) magnetic resonance (MR) images and evaluate the diagnostic performance of MR imaging in detection of central zone involvement by prostate cancer. MATERIALS AND METHODS/METHODS:The institutional review board waived informed consent and approved this retrospective, HIPAA-compliant study of 211 patients who underwent T2-weighted and DW MR imaging of the prostate before radical prostatectomy. Whole-mount step-section pathologic findings were the reference standard. Two radiologists independently recorded the visibility, MR signal intensity, size, and symmetry of the central zone and scored the likelihood of central zone involvement by cancer on T2-weighted MR images and on T2-weighted MR images plus apparent diffusion coefficient (ADC) maps generated from the DW MR images. Descriptive summary statistics were calculated for central zone imaging features. Sensitivity, specificity, and area under the curve were used to evaluate reader performance in detecting central zone involvement. RESULTS:For readers 1 and 2, the central zone was visible, at least partially, in 177 (84%) and 170 (81%) of 211 patients, respectively. The most common imaging appearance of the central zone was symmetric, homogeneous low signal intensity. Cancers involving the central zone had higher prostate-specific antigen values, Gleason scores, and rates of extracapsular extension and seminal vesicle invasion compared with cancers not involving the central zone (P < .05). Area under the curve, sensitivity, and specificity in detecting central zone involvement were 0.70, 0.30, and 0.96 for reader 1 and 0.65, 0.35, and 0.93 for reader 2, and these values did not differ significantly between T2-weighted imaging and T2-weighted imaging plus ADC maps. CONCLUSION/CONCLUSIONS:The central zone was visualized in most patients. Cancers involving the central zone were associated with more aggressive disease than those without central zone involvement.

PURPOSE/OBJECTIVE:To retrospectively determine the prevalence and positive predictive value (PPV) of the hemorrhage exclusion sign on T1-weighted magnetic resonance (MR) images in conjunction with findings on T2-weighted images in the detection of prostate cancer, with use of whole-mount step-section pathologic specimens from prostatectomy as the reference standard. MATERIALS AND METHODS/METHODS:The institutional review board approved this retrospective study, which was compliant with HIPAA, and the requirement to obtain informed consent was waived. Two hundred ninety-two patients with biopsy-proved prostate cancer underwent endorectal MR imaging followed by prostatectomy. The hemorrhage exclusion sign was defined as the presence of a well-defined area of low signal intensity surrounded by areas of high signal intensity on T1-weighted images. Two readers independently assessed the presence and extent of postbiopsy changes and the hemorrhage exclusion sign. The presence of a corresponding area of homogeneous low signal intensity on T2-weighted images was also recorded. The prevalence and PPV of the hemorrhage exclusion sign were calculated. RESULTS:Readers 1 and 2 found postbiopsy changes in the peripheral zone in 184 (63%) and 189 (64.7%) of the 292 patients, respectively. In these patients, the hemorrhage exclusion sign was observed in 39 of 184 patients (21.2%) by reader 1 and 36 of 189 patients (19.0%) by reader 2. A corresponding area of homogeneous low signal intensity was seen on T2-weighted images in the same location as the hemorrhage exclusion sign in 23 of 39 patients (59%) by reader 1 and 19 of 36 patients (53%) by reader 2. The PPV of the hemorrhage exclusion sign alone was 56% (22 of 39 patients) for reader 1 and 50% (18 of 36 patients) for reader 2 but increased to 96% (22 of 23 patients) and 95% (18 of 19 patients) when the sign was identified in an area of homogeneous low signal intensity on T2-weighted images. CONCLUSION/CONCLUSIONS:Postbiopsy change is a known pitfall in the interpretation of T2-weighted images. The authors have shown that a potential benefit of postbiopsy change is the presence of excluded hemorrhage, which, in conjunction with a corresponding area of homogeneous low signal intensity at T2-weighted imaging, is highly accurate for cancer identification.

BACKGROUND AND PURPOSE/OBJECTIVE:The role of DCE-MR imaging in the study of bone marrow perfusion is only partially developed, though potential applications for routine use in the clinical setting are beginning to be described. We hypothesize that DCE-MR imaging can be used to discriminate between hypervascular and hypovascular metastases based on measured perfusion variables. MATERIALS AND METHODS/METHODS:We conducted a retrospective study of 26 patients using conventional MR imaging and DCE-MR imaging. Patients were assigned to a hypervascular or hypovascular group based on tumor pathology. ROIs were drawn around normal-appearing bone marrow (internal controls) and enhancing tumor areas. Average wash-in enhancement slope, average peak enhancement signal percentage change, and average peak enhancement signal percentage change in areas of highest wash-in enhancement slope were calculated. Indices were compared among control, hypervascular, and hypovascular groups. Conventional imaging was assessed by calculating pre- to postgadolinium signal percentage changes in hypervascular and hypovascular lesions. RESULTS:Hypervascular and hypovascular tumors differed significantly with regard to wash-in enhancement slope (P < .01; hypervascular 95% CI, 22.5-26.5 AU/s; hypovascular 95% CI, 14.1-20.9 AU/s) and peak enhancement signal percentage change in areas of highest wash-in enhancement slope (P < .01; hypervascular 95% CI, 174.1-323.3%; hypovascular 95% CI, 39.5-150.5%). Peak enhancement signal percentage change over all voxels was not significant (P = .62). Areas of normal-appearing marrow showed no appreciable contrast enhancement. Conventional contrast-enhanced MR imaging was unable to differentiate between hypervascular and hypovascular tumors (P = .58). CONCLUSIONS:Our data demonstrate that, unlike conventional MR imaging sequences, DCE-MR imaging may be a more accurate technique in discriminating hypervascular from hypovascular spinal metastases.