Faculty Bibliography

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:To assess the association between clear-cell carcinoma pathology grade at nephrectomy and magnetic resonance imaging (MRI) tumor enhancement. MATERIALS AND METHODS/METHODS:The Institutional Review Board approved this retrospective study and waived the informed consent requirement. In all, 32 patients underwent multiphase contrast-enhanced MRI prior to nephrectomy. MRI tumor enhancement was measured using two approaches: 1) the most enhancing portion of the tumor on a single slice and 2) volumetric analysis of enhancement in the entire tumor. Associations between pathological grade, tumor size, and enhancement were evaluated using the Kruskal-Wallis test and generalized logistic regression models. RESULTS:No significant association between pathology grade and enhancement was found when measurements were made on a single slice. When measured in the entire tumor, significant associations were found between higher pathology grades and lower mean, median, top 10%, top 25%, and top 50% tumor enhancement (P < 0.001-0.002). On multivariate analysis the association between grade and enhancement remained significant (P = 0.041-0.043), but tumor size did not make an additional contribution beyond tumor enhancement alone in differentiating between tumor grades. CONCLUSION/CONCLUSIONS:There is significant association between tumor grade and enhancement, but only when measured in the entire tumor and not on the most enhancing portion on a single slice.

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.

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.

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.

PURPOSE/OBJECTIVE:To prospectively evaluate the diagnostic performance of magnetic resonance imaging (MRI), (11)C-acetate positron emission tomography/computed tomography (PET/CT) and contrast-enhanced CT for bladder cancer staging, using whole-mount pathologic review of radical cystectomy and pelvic lymph node specimens as the reference standard. MATERIALS AND METHODS/METHODS:The institutional review board approved this prospective study, which was compliant with the Health Insurance Portability and Accountability Act. Written informed consent was obtained from 16 patients with histologically confirmed bladder cancer who underwent MRI, (11)C-acetate PET/CT and contrast-enhanced CT before radical cystectomy and pelvic lymph node dissection. Before imaging 4/16 patients had received intravesical Bacillus Calmette-Guérin treatment, 6 had received systemic chemotherapy, 3 had received both and 3 had received neither. Measures of diagnostic performance including accuracy, sensitivity and specificity were estimated separately for each imaging modality. RESULTS:MRI correctly staged 56% of patients (9/16), overstaged 38% (6/16) and understaged 6% (1/16). CT correctly staged 50% of patients (8/16), overstaged 44% (7/16) and understaged 6% (1/16). In 9 patients, (11)C-acetate PET/CT showed uptake within the bladder wall; the uptake was true-positive in 7 patients and false-positive in 2 patients. Of the remaining 7 patients, 5 had true-negative and 2 had false-negative PET/CT results for cancer in the bladder wall. For all modalities, staging accuracy was reduced in patients with a history of prior intravesical and/or systemic chemotherapy. CONCLUSION/CONCLUSIONS:In staging bladder cancer, MRI, (11)C-acetate PET/CT and CT displayed similar levels of accuracy. For all modalities, a history of intravesical and/or systemic chemotherapy affected staging accuracy.

PURPOSE/OBJECTIVE:To prospectively evaluate diagnostic performance of T2-weighted magnetic resonance (MR) imaging and MR spectroscopic imaging in detecting lesions stratified by pathologic volume and Gleason score in men with clinically determined low-risk prostate cancer. MATERIALS AND METHODS/METHODS:The institutional review board approved this prospective, HIPAA-compliant study. Written informed consent was obtained from 183 men with clinically low-risk prostate cancer (cT1-cT2a, Gleason score≤6 at biopsy, prostate-specific antigen [PSA] level<10 ng/mL [10 μg/L]) undergoing MR imaging before prostatectomy. By using a scale of 1-5 (score 1, definitely no tumor; score 5, definitely tumor), two radiologists independently scored likelihood of tumor per sextant on T2-weighted images. Two spectroscopists jointly recorded locations of lesions with metabolic features consistent with tumor on MR spectroscopic images. Whole-mount step-section histopathologic analysis constituted the reference standard. Diagnostic performance at sextant level (T2-weighted imaging) and detection sensitivities (T2-weighted imaging and MR spectroscopic imaging) for lesions of 0.5 cm3 or larger were calculated. RESULTS:For T2-weighted imaging, areas under the receiver operating characteristic curves for sextant-level detection were 0.77 (reader 1) and 0.82 (reader 2). For lesions of ≥0.5 cm3 and, 1<cm3, sensitivities were significantly lower when the lesion Gleason score was ≤6 (0.44 [reader 1] and 0.61 [reader 2]) rather than when the Gleason score was ≥7 (0.73, P=.02 [reader 1]; and 0.84, P=.05 [reader 2]). For lesions of ≥1 cm3, lesion Gleason score did not significantly affect sensitivity (0.83 [reader 1] and 1.00 [reader 2] for Gleason score≤6 vs 0.82 and 0.92 for Gleason score≥7; P≥.07). MR spectroscopic imaging sensitivity was low and was not significantly affected by pathologic lesion volume or Gleason score. CONCLUSION/CONCLUSIONS:In men with clinically low-risk prostate cancer, detection of lesions of <1 cm3 with T2-weighted imaging is significantly dependent on lesion Gleason score; detection of lesions of ≥1 cm3 is significantly better than detection of smaller lesions and is not affected by lesion Gleason score. The role of MR spectroscopic imaging alone in this population is limited.