Faculty Bibliography

MRI provides exquisite views of the pelvic anatomy through its high spatial resolution and tissue contrast, and as such plays a key role in the work up of ovarian lesions, identifying features that distinguish benign and malignant lesions. In the case of primary tumors it enables local staging and detection of metastatic disease to help guide management options such as complex surgery or the consideration of neoadjuvant chemotherapy. Functional MRI techniques such as diffusion-weighted MRI (DW-MRI), dynamic contrast-enhanced MRI (DCE-MRI) and tumor-selective molecular imaging are currently being evaluated as possible predictive and prognostic biomarkers in the context of ovarian malignancy, and may play a larger role in routine clinical practice in the future. Herein we provide an overview of the conventional and advanced MRI techniques used to characterize ovarian masses and of the role that MR plays in the staging, treatment selection and follow up of patients with ovarian cancer.

OBJECTIVE:In patients undergoing pelvic exenteration for recurrent gynecological malignancies, we assessed the performance of [(18)F]-FDG PET/CT for delineating disease extent and evaluated the association between quantitative FDG uptake metrics (SUVmax, total lesion glycolysis [TLG] and metabolic tumor volume [MTV]) and progression-free survival (PFS) and overall survival (OS). METHODS:Retrospective study of patients undergoing pelvic exenteration for gynecologic malignancies between January 2002 and November 2011 who had FDG PET/CT within 90days before surgery. Two readers (R1, R2) independently determined the presence of bladder, rectum, vagina, cervix and pelvic side wall invasion and measured SUVmax, TLG and MTV in each patient. Areas under the curve (AUCs), for detecting organ invasion were calculated. Kaplan-Meier graphs were used to determine associations between FDG uptake and PFS/OS. Inter-reader agreement was assessed. RESULTS:33 patients (mean age 56years, range: 28-81) were included; primary sites of disease were the cervix (n=18), uterus (n=8) and vagina/vulva (n=7). AUCs for organ invasion ranged from 0.74 to 0.96. There was a significant association between FDG uptake metrics incorporating tumor volume (TLG and MTV) and OS (p≤0.001) as well as between MTV and PFS (p=0.001). No significant association was identified between SUVmax and OS/PFS (p=0.604/0.652). Inter-reader agreement for organ invasion was fair to substantial (k=0.36-0.74) and almost perfect for FDG quantification (ICC=0.97-0.99). CONCLUSION/CONCLUSIONS:In patients undergoing pelvic exenteration for recurrent gynecological malignancies, (18)F-FDG PET/CT is useful for preoperative assessment of disease extent. Furthermore, quantitative metrics of FDG uptake incorporating MTV serve as predictive biomarkers of progression-free and overall survival in this population.

PURPOSE/OBJECTIVE:Based on prior reports suggesting a positive correlation between fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)/CT and total sperm count and concentration, we sought to identify changes in testicular FDG uptake over the course of chemotherapy in young men with Hodgkin's lymphoma. METHODS:Fifty-two patients with a mean age of 24.2 years (range 15.5-44.4) at diagnosis monitored with FDG PET/CT to assess treatment response for Hodgkin's lymphoma were selected for this retrospective analysis under an Institutional Review Board waiver. Of the patients, 26 were treated with a chemotherapy regimen known to cause prolonged and sometimes permanent azoospermia (BEACOPP--bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone) and 26 with a regimen known to have a much milder effect on gonadal function (ABVD--doxorubicin, bleomycin, vincristine, and dacarbazine). Each patient underwent one FDG PET/CT before treatment and at least one FDG PET/CT after start of chemotherapy. In all examinations, FDG activity was measured in the testes with different quantification metrics: maximum standardized uptake value (SUVmax), SUVmean, functional volume (FV) and total testicular glycolysis (TTG), and blood pool activity determined (SUVmean). RESULTS:Testicular FDG uptake (SUVmax) was significantly associated with blood pool activity (p < 0.001). Furthermore, testicular FDG uptake metrics incorporating volume (e.g., FV and TTG) were associated with age. There was no significant change in SUVmax, SUVmean, FV, and TTG from the PET/CT at baseline to the PET/CTs over the course of chemotherapy either for patients treated with BEACOPP or for patients treated with ABVD. CONCLUSION/CONCLUSIONS:For patients undergoing chemotherapy for Hodgkin's lymphoma, there is a significant association between testicular FDG uptake and blood pool activity, but no significant changes in FDG uptake over the course of chemotherapy. Therefore, FDG uptake may not be a feasible surrogate marker for fertility monitoring in patients with Hodgkin's lymphoma undergoing chemotherapy.

PURPOSE/OBJECTIVE:To compare diagnostic accuracy of T2-weighted magnetic resonance (MR) imaging with that of multiparametric (MP) MR imaging combining T2-weighted imaging with diffusion-weighted (DW) MR imaging, dynamic contrast material-enhanced (DCE) MR imaging, or both in the detection of locally recurrent prostate cancer (PCa) after radiation therapy (RT). MATERIALS AND METHODS/METHODS:This retrospective HIPAA-compliant study was approved by the institutional review board; informed consent was waived. Fifty-three men (median age, 70 years) suspected of having post-RT recurrence of PCa underwent MP MR imaging, including DW and DCE sequences, within 6 months after biopsy. Two readers independently evaluated the likelihood of PCa with a five-point scale for T2-weighted imaging alone, T2-weighted imaging with DW imaging, T2-weighted imaging with DCE imaging, and T2-weighted imaging with DW and DCE imaging, with at least a 4-week interval between evaluations. Areas under the receiver operating characteristic curve (AUC) were calculated. Interreader agreement was assessed, and quantitative parameters (apparent diffusion coefficient [ADC], volume transfer constant [K(trans)], and rate constant [k(ep)]) were assessed at sextant- and patient-based levels with generalized estimating equations and the Wilcoxon rank sum test, respectively. RESULTS:At biopsy, recurrence was present in 35 (66%) of 53 patients. In detection of recurrent PCa, T2-weighted imaging with DW imaging yielded higher AUCs (reader 1, 0.79-0.86; reader 2, 0.75-0.81) than T2-weighted imaging alone (reader 1, 0.63-0.67; reader 2, 0.46-0.49 [P ≤ .014 for all]). DCE sequences did not contribute significant incremental value to T2-weighted imaging with DW imaging (reader 1, P > .99; reader 2, P = .35). Interreader agreement was higher for combinations of MP MR imaging than for T2-weighted imaging alone (κ = 0.34-0.63 vs κ = 0.17-0.20). Medians of quantitative parameters differed significantly (P < .0001 to P = .0233) between benign tissue and PCa (ADC, 1.64 × 10(-3) mm(2)/sec vs 1.13 × 10(-3) mm(2)/sec; K(trans), 0.16 min(-1) vs 0.33 min(-1); k(ep), 0.36 min(-1) vs 0.62 min(-1)). CONCLUSION/CONCLUSIONS:MP MR imaging has greater accuracy in the detection of recurrent PCa after RT than T2-weighted imaging alone, with no additional benefit if DCE is added to T2-weighted imaging and DW imaging.

In patients with a clinical suspicion of recurrence after treatment for prostate cancer, imaging can be used to distinguish between local recurrence and metastatic disease. Multiparametric magnetic resonance imaging (mpMRI) of the prostate may be a valuable imaging modality for the detection and localization of local recurrence in patients treated for prostate cancer. In mpMRI, morphological T2-weighted images are combined with functional MRI techniques including diffusion-weighted imaging, dynamic contrast-enhanced imaging, and magnetic resonance spectroscopic imaging to improve accuracy. In this paper, the current status of imaging techniques used to detect and to localize tumor recurrence in patients treated for prostate cancer will be reviewed, with emphasis on mpMRI for local prostate cancer recurrence.

PURPOSE/OBJECTIVE:To determine the diagnostic performance of MRI in assessing local tumour extent and evaluate associations between MRI features and survival in patients undergoing MRI before pelvic exenteration for persistent or recurrent gynaecological cancers. METHODS AND MATERIALS/METHODS:The study included 50 patients with persistent or recurrent gynaecological malignancies who underwent pelvic exenteration between January 1999 and December 2011 and had MRI at most 90 days before surgery. Two radiologists independently assessed invasion of adjacent organs (on a 5-point scale). Diagnostic accuracy, inter-reader agreement, and associations between organ invasion on MRI and patient survival were evaluated. RESULTS:Areas under receiver operating characteristic curves (AUCs) for invasion of the bladder, rectum and pelvic sidewall were 0.96, 0.90 and 0.98 for reader 1 and 0.95, 0.88 and 0.90 for reader 2. Corresponding sensitivities/specificities were 87.0 %/92.6 %, 81.3 %/97.0 % and 87.5 %/97.2 % for reader 1, and 87.0 %/100.0 %, 75.0 %/97.0 % and 75.0 %/94.4 % for reader 2. Inter-reader agreement was excellent for organ invasion (κ = 0.81-0.85). Pelvic sidewall invasion on MRI was associated with overall and recurrence-free survival (P = 0.01-0.04 for the two readers). CONCLUSION/CONCLUSIONS:Preoperative MRI is accurate in predicting organ invasion. It may guide surgical planning and serve as a predictive biomarker in patients undergoing pelvic exenteration for gynaecological malignancies. KEY POINTS/CONCLUSIONS:• MRI can accurately assess bladder and rectal wall invasion before major surgery. • MRI identifies patients requiring extended pelvic exenteration by detecting sidewall invasion. • Inter-reader agreement for detecting organ invasion and tumor size is excellent. • Pelvic sidewall invasion on MRI is associated with shorter overall and recurrence-free survival.

PURPOSE/OBJECTIVE:To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC+PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T. METHODS:The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Twenty-five patients with biopsy-proven prostate cancer underwent standard 3-T MRI using 2 different coil arrangements (ERC+PAC and PAC only) in the same session. DW-MRI at five b-values (0, 600, 1000, 1200, and 1500 s/mm(2)) were acquired using both coil arrangements. On b=0 images, signal-to-noise ratios (SNRs) were measured as the ratio of the mean signal from PZ and TZ ROIs to the standard deviation from the mean signal in an artifact-free ROI in the rectum. Matching regions-of-interest (ROIs) were identified in the peripheral zone and transition zone on ERC-MRI and PAC-MRI. For each ROI, mean ADC values for all zero and non-zero b-value combinations were computed. RESULTS:Mean SNR with ERC-MRI at PZ (66.33 ± 27.07) and TZ (32.69 ± 12.52) was 9.27 and 5.52 times higher than with PAC-MRI ((7.32 ± 2.30) and (6.13 ± 1.56), respectively) (P<0.0001 for both). ADCs from DW-MR images obtained with all b-values in the PZ and TZ were significantly lower with PAC-MRI than with ERC-MRI (P<0.001 for all). CONCLUSION/CONCLUSIONS:Lower SNR of DW-MR images of the prostate obtained with a PAC can significantly decrease ADC values at higher b-values compared to similar measurements obtained using the ERC. To address these requirements, clinical MR systems should have image processing capabilities which incorporate the noise distribution.

RATIONALE AND OBJECTIVES/OBJECTIVE:To identify the presence and extent of artifacts in prostate diffusion-weighted magnetic resonance imaging (DW-MRI) and discuss tradeoffs between imaging at 1.5 T (1.5 T) and 3.0 T (3.0 T). In addition, we aim to provide quantitative estimates of signal-to-noise ratios (SNRs) at both field strengths. MATERIALS AND METHODS/METHODS:The institutional review board waived informed consent for this Health Insurance Portability and Accountability Act-compliant, retrospective study of 53 consecutive men who underwent 3.0 T endorectal DW-MRI and 53 consecutive men who underwent 1.5 T endorectal DW-MRI between October and December 2010. One radiologist and one physicist, blinded to patient characteristics, image acquisition parameters, and field strength, scored DW-MRI artifacts. On b = 0 images, SNR was measured as the ratio of the mean signal from a region of interest (ROI) at the level of the verumontanum (the "reference region") to the standard deviation from the mean signal in an artifact-free ROI in the rectum. RESULTS:Both readers found geometric distortion and signal graininess significantly more often at 3.0 T than at 1.5 T (P < .0001, all comparisons). Reader 2 (but not reader 1) found ghosting artifacts more often at 3.0 T (P = .001) and blurring more often at 1.5 T (P = .006). Mean SNR at the urethra (87.92 ± 27.76) at 3.0 T was 1.43 times higher than at 1.5 T (64.51 ± 14.96) (P < .0001). CONCLUSIONS:At 3.0 T (as compared to 1.5 T), increased SNR on prostate DW-MRI comes at the expense of geometric distortion and can also lead to more pronounced ghosting artifacts. Therefore, to take full advantage of the benefits of 3.0 T, further improvements in acquisition techniques are needed to address DW-MRI artifacts corresponding to higher field strengths.

PURPOSE/OBJECTIVE:To evaluate the incremental value of using diffusion-weighted magnetic resonance (MR) imaging in addition to T2-weighted imaging for the detection of prostate cancer in the transition zone and the assessment of tumor aggressiveness. MATERIALS AND METHODS/METHODS:This retrospective HIPAA-compliant institutional review board-approved study included 156 consecutive patients (median age, 59.2 years) who underwent MR imaging before radical prostatectomy. Two readers who were blinded to patient data independently recorded their levels of suspicion on a five-point scale of the presence of transition zone tumors on the basis of T2-weighted imaging alone and then, 4 weeks later, diffusion-weighted imaging and T2-weighted imaging together. Apparent diffusion coefficients (ADCs) were measured in transition zone cancers and glandular and stromal benign prostatic hyperplasia. Areas under the receiver operating characteristic curves were used to evaluate detection accuracy, and generalized linear models were used to test ADC differences between benign and malignant prostate regions. Whole-mount step-section histopathologic examination was the reference standard. RESULTS:In overall tumor detection, addition of diffusion-weighted imaging to T2-weighted imaging improved the areas under the receiver operating characteristic curves for readers 1 and 2 from 0.60 and 0.60 to 0.75 and 0.71, respectively, at the patient level (P = .004 for reader 1 and P = .027 for reader 2) and from 0.64 and 0.63 to 0.73 and 0.68, respectively, at the sextant level (P = .001 for reader 1 and P = .100 for reader 2). Least squares mean ADCs (× 10(-3) mm(2)/sec) in glandular and stromal benign prostatic hyperplasia were 1.44 and 1.09, respectively. Mean ADCs were inversely associated with tumor Gleason scores (1.10, 0.98, 0.87, and 0.75 for Gleason scores of 3 + 3, 3 + 4, 4 + 3, and ≥ 4 + 4, respectively). CONCLUSION/CONCLUSIONS:Use of diffusion-weighted imaging in addition to T2-weighted imaging improved detection of prostate cancer in the transition zone, and tumor ADCs were inversely associated with tumor Gleason scores in the transition zone.