Prostate cancer: Endorectal MR imaging and MR spectroscopic imaging - Distinction of true-positive results from chance-detected lesions
ABSTRACT To retrospectively investigate size criteria for the identification of chance-detected lesions at endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging of prostate cancer.
Approval of the committee on human research and written informed consent were obtained. This study was HIPAA compliant. Endorectal MR imaging and MR spectroscopic imaging were performed with a 1.5-T MR imager in 48 men with a mean age of 59 years (age range, 47-75 years) prior to radical prostatectomy. Two independent readers recorded the size and location of all suspected peripheral zone tumor nodules on MR images alone and on images obtained with combined MR imaging and MR spectroscopic imaging. Nodules detected at MR imaging were classified as matched lesions if tumor was present in the same location at step-section histopathologic review. For all matched lesions, kappa values were calculated to examine agreement between measured and actual tumor size. Lesions that were overmeasured at MR imaging with a kappa value of less than 0.2 were considered chance-detected lesions.
At MR imaging, two of 27 and four of 35 matched lesions for readers 1 and 2, respectively, were chance-detected lesions. The corresponding numbers of lesions at combined MR imaging and MR spectroscopic imaging were one of 21 and one of 31, respectively. In all but two cases, the measured diameter of chance-detected lesions was more than twice that of the diameter at histopathologic analysis. By using this diameter threshold to distinguish true-positive results, the mean diameter of detected tumors at histopathologic analysis was 15 mm compared with 4 mm for both undetected and chance-detected tumors (P < .05).
To ensure uniformity in the comparison of scientific studies, peripheral zone tumors detected at MR imaging and MR spectroscopic imaging of the prostate that are in the same location as tumors detected at histopathologic review should be considered chance-detected lesions if the MR transverse diameter is more than twice the histopathologic transverse diameter.
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ABSTRACT: Prostatic neoplasms are not uniformly distributed within the prostate volume. With recent developments in three-dimensional intensity-modulated and image-guided radiation therapy, it is possible to treat different volumes within the prostate to different thresholds of doses. This approach has the potential to adapt the dose to the biologic aggressiveness of various clusters of tumor cells within the gland. The definition of tumor burden volume in prostate cancer can be facilitated by the use of magnetic resonance spectroscopy (MRS). The increasing sensitivity and specificity of MRS to the prostate is causing new interest in its potential role in the definition of target subvolumes at higher risk of failure following radical radiotherapy. Prostate MRS might also play a role as a noninvasive predictive factor for tumor response and treatment outcome. We review the use of MRS in radiation therapy for prostate cancer by evaluating its accuracy in the classification of aggressive cancer regions and target definition; its current role in the radiotherapy planning process, with special interest in technical issues behind the successful inclusion of MRS in clinical use; and available early experiences as a prognostic tool.Neoplasia (New York, N.Y.) 07/2007; 9(6):455-63. DOI:10.1593/neo.07277 · 5.40 Impact Factor
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ABSTRACT: To prospectively determine the accuracy of in vivo proton ((1)H) magnetic resonance (MR) spectroscopy in distinguishing adrenal adenomas, pheochromocytomas, adrenocortical carcinomas, and metastases, with histologic or computed tomographic findings and follow-up data as the reference standards. This study was approved by the institutional ethics committee, and informed consent was obtained. Sixty consecutive patients (24 male and 36 female patients; mean age, 53 years) harboring adrenal tumors larger than 2 cm in diameter (mean diameter, 4.6 cm +/- 3.4 [standard deviation]) entered the study and were examined with a 1.5-T MR imaging system and point-resolved multivoxel (1)H MR spectroscopy. Thirty-eight patients had adenomas; 10, pheochromocytomas; five, carcinomas; and seven, metastases. Amplitude values for choline, creatine, lipid, and a metabolite peak at precession frequency of 4.0-4.3 ppm were measured. Metabolite ratios (choline-creatine, choline-lipid, lipid-creatine, and 4.0-4.3 ppm/creatine) and cutoff values (obtained by using receiver operating characteristic analyses) were obtained and compared for each type of adrenal mass, which was identified previously on the basis of clinical, hormonal, and pathologic evidence. Results were evaluated with chi(2) and Student t tests. Significance was inferred at P < .05. Cutoff values of 1.20 for the choline-creatine ratio (92% sensitivity, 96% specificity; P < .01), 0.38 for the choline-lipid ratio (92% sensitivity, 90% specificity; P < .01), and 2.10 for the lipid-creatine ratio (45% sensitivity, 100% specificity) enabled adenomas and pheochromocytomas to be distinguished from carcinomas and metastases. A 4.0-4.3 ppm/creatine ratio greater than 1.50 enabled distinction of pheochromocytomas and carcinomas from adenomas and metastases (87% sensitivity, 98% specificity; P < .01). The best distinction was obtained by comparing choline-creatine and 4.0-4.3 ppm/creatine ratios. (1)H MR spectroscopy can be used to characterize adrenal masses on the basis of spectral findings for benign adenomas, carcinomas, pheochromocytomas, and metastases.Radiology 12/2007; 245(3):788-97. DOI:10.1148/radiol.2453061854 · 6.21 Impact Factor
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ABSTRACT: PURPOSE: To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy. MATERIALS AND METHODS: We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm(3) ) dominant intraprostatic tumor foci. RESULTS: Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio = 1.75; 95% confidence interval = 1.08 to 2.82; P value = 0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm(3) of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci. CONCLUSION: Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm(3) of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.Journal of Magnetic Resonance Imaging 03/2014; 39(3). DOI:10.1002/jmri.24187 · 2.79 Impact Factor