Prostate cancer tumor volume: measurement with endorectal MR and MR spectroscopic imaging

PURPOSE: To determine accuracy of magnetic resonance (MR) and three-dimensional (3D) MR spectroscopic imaging in prostate cancer tumor volume measurement. MATERIALS AND METHODS: Endorectal MR and 3D MR spectroscopic imaging were performed in 37 patients before radical prostatectomy. Two independent readers recorded peripheral zone tumor nodule location and volume. Results were analyzed with step-section histopathologic tumor localization and volume measurement as the standard. Accuracy of tumor volume measurement was assessed with the Pearson correlation coefficient. P values were calculated with a random effects model. Bland-Altman regression analysis was used to evaluate systematic bias between tumor volumes measured with MR imaging and true tumor volumes. Analyses were performed for all nodules and nodules greater than 0.50 cm(3). RESULTS: Mean volume of peripheral zone tumor nodules (n = 51) was 0.79 cm(3) (range, 0.02-3.70 cm(3)). Two readers detected 20 (65%) and 23 (74%) of 31 peripheral zone tumor nodules greater than 0.50 cm(3). For these nodules, measurements of tumor volume with MR imaging, 3D MR spectroscopic imaging, and a combination of both were all positively correlated with histopathologic volume (Pearson correlation coefficients of 0.49, 0.59, and 0.55, respectively); only measurements with 3D MR spectroscopic imaging and a combination of MR and 3D MR spectroscopic imaging demonstrated statistical significance (P <.05). Tumor volume estimation with all three methods was more accurate for higher tumor volumes. CONCLUSION: Addition of 3D MR spectroscopic imaging to MR imaging increases overall accuracy of prostate cancer tumor volume measurement, although measurement variability limits consistent quantitative tumor volume estimation, particularly for small tumors.     

Prostate cancer localization with endorectal MR imaging and MR spectroscopic imaging: effect of clinical data on reader accuracy

PURPOSE: To determine the effect of digital rectal examination findings, sextant biopsy results, and prostate-specific antigen (PSA) levels on reader accuracy in the localization of prostate cancer with endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging. MATERIALS AND METHODS: This was a retrospective study of 37 patients (mean age, 57 years) with biopsy-proved prostate cancer. Transverse T1-weighted, transverse high-spatial-resolution, and coronal T2-weighted MR images and MR spectroscopic images were obtained. Two independent readers, unaware of clinical data, recorded the size and location of suspicious peripheral zone tumor nodules on a standardized diagram of the prostate. Readers also recorded their degree of diagnostic confidence for each nodule on a five-point scale. Both readers repeated this interpretation with knowledge of rectal examination findings, sextant biopsy results, and PSA level. Step-section histopathologic findings were the reference standard. Logistic regression analysis with generalized estimating equations was used to correlate tumor detection with clinical data, and alternative free-response receiver operating characteristic (AFROC) curve analysis was used to examine the overall effect of clinical data on all positive results. RESULTS: Fifty-one peripheral zone tumor nodules were identified at histopathologic evaluation. Logistic regression analysis showed awareness of clinical data significantly improved tumor detection rate (P <.02) from 15 to 19 nodules for reader 1 and from 13 to 19 nodules for reader 2 (27%-37% overall) by using both size and location criteria. AFROC analysis showed no significant change in overall reader performance because there was an associated increase in the number of false-positive findings with awareness of clinical data, from 11 to 21 for reader 1 and from 16 to 25 for reader 2. CONCLUSION: Awareness of clinical data significantly improves reader detection of prostate cancer nodules with endorectal MR imaging and MR spectroscopic imaging, but there is no overall change in reader accuracy, because of an associated increase in false-positive findings. A stricter definition of a true-positive result is associated with reduced sensitivity for prostate cancer nodule detection.     

Prostate cancer: localization with three-dimensional proton MR spectroscopic imaging--clinicopathologic study.

PURPOSE: To assess the efficacy of combined magnetic resonance (MR) imaging and three-dimensional (3D) proton MR spectroscopic imaging in the detection and localization of prostate cancer. MATERIALS AND METHODS: MR imaging and 3D MR spectroscopic imaging examinations were performed in 53 patients with biopsy-proved prostate cancer and subsequent radical prostatectomy with step-section histopathologic examination. The prostate was divided into sextants. At MR imaging, the presence or absence of cancer in the peripheral zone of each sextant was assessed independently by two readers (readers 1 and 2) unaware of the findings at 3D MR spectroscopic imaging and histopathologic examination. At 3D MR spectroscopic imaging, cancer was diagnosed as possible if the ratio of choline plus creatine to citrate exceeded 2 SD above population norms or as definite if that ratio exceeded 3 SDs above the norm. RESULTS: On the basis of sextants, sensitivity and specificity, respectively, for MR imaging were 77% and 61% (reader 1) and 81% and 46% (reader 2) with moderate interreader agreement (kappa = 0.43). The 3D MR spectroscopic imaging diagnosis of definite cancer had significantly higher specificity (75%, P < .05) but lower sensitivity (63%, P < .05). Receiver operating characteristic analysis showed significantly (P < .001) improved tumor localization for both readers when 3D MR spectroscopic imaging was added to MR imaging. High specificity (up to 91%) was obtained when combined MR imaging and 3D MR spectroscopic imaging indicated cancer, whereas high sensitivity (up to 95%) was obtained when either test alone indicated a positive result. CONCLUSION: The addition of 3D MR spectroscopic imaging to MR imaging provides better detection and localization of prostate cancer in a sextant of the prostate than does use of MR imaging alone.     

Characterization of bone and soft-tissue tumors with in vivo 1H MR spectroscopy: initial results

PURPOSE: To determine if in vivo detection of choline by using hydrogen 1 (1H) magnetic resonance (MR) spectroscopy with dynamic contrast material-enhanced MR imaging can help differentiate between benign and malignant musculoskeletal tumors. MATERIALS AND METHODS: MR imaging was performed in 36 consecutive patients with bone and soft-tissue tumors larger than 1.5 cm in diameter. Examinations were performed at 1.5 T with a surface coil appropriate for the location of the lesions. Single-voxel 1H MR spectroscopy was performed by using a point-resolved spectroscopic sequence with echo times of 40, 135, and 270 msec. The volume of interest within lesions was positioned on the areas of early enhancement (<8 seconds after arterial enhancement) according to the findings of dynamic contrast-enhanced MR imaging with subtraction. The criterion for determining whether choline was present in a lesion was a clearly identifiable peak at 3.2 ppm in at least two of the three spectra acquired at echo times. MR spectroscopic results and histopathologic findings were determined in blinded fashion and compared with kappa statistics. P <.001 was considered to indicate a significant difference. RESULTS: Choline was detected in 18 of 19 patients with malignant tumors and in three of 17 patients with benign lesions. The three benign lesions included one perineurioma, one giant cell tumor, and one abscess. Choline was not detected in 14 patients with benign lesions nor in one patient with a densely ossifying low-grade parosteal osteosarcoma. In vivo 1H MR spectroscopy characterized bone and soft-tissue tumors, resulting in a sensitivity of 95%, specificity of 82%, and accuracy of 89% (P <.001). CONCLUSION: Choline can be reliably detected in large malignant bone and soft-tissue tumors by using a multiecho point-resolved spectroscopic protocol. 1H MR spectroscopy can help differentiate malignant from benign musculoskeletal tumors by revealing the presence or absence of water-soluble choline metabolites.     

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-four consecutive men with a mean age of 60 years and a mean prostate-specific antigen level of 8 ng/mL were examined. The median biopsy Gleason score was 6. T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and 3D MR spectroscopic imaging were performed, and on the basis of the image data, two readers with different levels of experience recorded the location of the suspicious peripheral zone and central gland tumor nodules on each of 14 standardized regions of interest (ROIs) in the prostate. The degree of diagnostic confidence for each ROI was recorded on a five-point scale. Localization accuracy and ROI-based receiver operating characteristic (ROC) curves were calculated. RESULTS: For both readers, areas under the ROC curve for T2-weighted MR, dynamic contrast-enhanced MR, and 3D MR spectroscopic imaging were 0.68, 0.91, and 0.80, respectively. Reader accuracy in tumor localization with dynamic contrast-enhanced imaging was significantly better than that with quantitative spectroscopic imaging (P < .01). Reader accuracy in tumor localization with both dynamic contrast-enhanced imaging and spectroscopic imaging was significantly better than that with T2-weighted imaging (P < .01). CONCLUSION: Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.     

High-grade prostatic intraepithelial neoplasia in patients with prostate cancer: MR and MR spectroscopic imaging features--initial experience

PURPOSE: To retrospectively determine the magnetic resonance (MR) and MR spectroscopic imaging features of high-grade prostatic intraepithelial neoplasia (HGPIN) in patients with prostate cancer. MATERIALS AND METHODS: Approval of the committee on human research was obtained, with a waiver of consent for this HIPAA-compliant study. Endorectal MR imaging and MR spectroscopic imaging were performed in 48 men (mean age, 59 years; range, 47-75 years) prior to radical prostatectomy for prostate cancer. T2-weighted signal intensity and metabolic ratios of peripheral zone HGPIN foci of 6 mm or greater in diameter were recorded by two readers with knowledge of step-section histopathologic findings using areas of confirmed normal and cancerous peripheral zone tissue for comparison. A random effects statistical model was used to compare metabolic ratios from normal, HGPIN, and cancer voxels. RESULTS: A total of 123 peripheral zone HGPIN foci with a mean diameter of 3 mm (range, 1-28 mm) were identified in 37 (77%) patients, but only 20 foci in 14 patients had a diameter of 6 mm or greater. Six foci were excluded, yielding 14 large HGPIN lesions from 11 patients in the final statistical analysis. The larger HGPIN foci were not associated with any focal reduction in T2-weighted signal intensity but demonstrated metabolic findings intermediate between normal and cancerous tissue; the mean ratios of choline (Cho) to creatine (Cr) for normal, HGPIN, and cancer were 0.92, 1.75, and 1.99, respectively, (P < .01), and the corresponding ratios of Cho plus Cr to citrate were 0.34, 0.50, and 0.78 (P < .01). CONCLUSION: HGPIN is metabolically intermediate between normal peripheral zone tissue and prostate cancer at MR spectroscopic imaging but does not manifest any MR imaging abnormality and is rarely of sufficient size to cause substantial error in evaluation of peripheral zone tumor extent in patients with prostate cancer.     

Prostate cancer: prediction of extracapsular extension with endorectal MR imaging and three-dimensional proton MR spectroscopic imaging.

PURPOSE: To determine if the addition of three-dimensional (3D) proton magnetic resonance (MR) spectroscopic imaging to endorectal MR imaging helps diagnose extracapsular extension (ECE) of prostate cancer. MATERIALS AND METHODS: Endorectal MR imaging and 3D MR spectroscopic imaging were performed in 53 patients with prostate cancer before radical prostatectomy. MR imaging studies were evaluated by two independent readers unaware of histopathologic findings. The presence of ECE was graded on a five-point scale. At 3D MR spectroscopic imaging, cancer was diagnosed if the ratio of choline plus creatine to citrate was 2 or more SDs above normal. The accuracy of MR imaging alone was compared with that of combined MR imaging and 3D MR spectroscopic imaging, with use of the step-section histopathologic results as the standard of reference. RESULTS: For the less experienced reader, the addition of 3D MR spectroscopic imaging to MR imaging significantly improved accuracy (area under the receiver operating characteristic curve [Az] = 0.75 vs Az = 0.62, P < .05). For the more experienced reader, the addition improved accuracy but not significantly (Az = 0.86 vs Az = 0.78). The addition also reduced interobserver variability (Az = 0.86 vs Az = 0.75). CONCLUSION: The addition of 3D MR spectroscopic imaging to MR imaging improves accuracy for less experienced readers and reduces interobserver variability in the diagnosis of ECE of prostate cancer.     

Improved detection of skull metastasis with diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: Metastasis to the skull is clinically important, but routine MR imaging offers moderate sensitivity for skull-metastasis detection in our experience. We sought to determine if diffusion-weighted MR imaging (DWI) could improve the detection of skull metastasis in patients with primary carcinomas that metastasized to bone compared with conventional MR imaging. MATERIALS AND METHODS: Seventy-five patients from the tumor registry of our institution with extracranial primary malignancy who had brain MR imaging with DWI and radionuclide bone scanning (RNBS, gold standard) within a 6-week interval were evaluated. Thirty-eight patients demonstrated increased radiopharmaceutical uptake on RNBS, consistent with skull metastasis of any size, and the remaining 37 were control subjects. Two readers correlated the DWI and conventional MR imaging with RNBS. RESULTS: The overall sensitivity of DWI for detection of skull metastases was 68.4%-71.1% (kappa=0.68) versus 42.1%-55.3% (kappa=0.65) for conventional MR imaging. Breast cancer (n=20) was detected with greatest sensitivity of 86.7%-93.3% (kappa=0.80) for DWI versus 60%-80% (kappa=0.5) for conventional MR imaging. Lung cancer (n=32) was detected with 63.6%-72.7% sensitivity (kappa=0.56), and prostate cancer (n=8) with 14.3% sensitivity (kappa=0.5) for DWI versus 27.3%-36.4% (kappa=0.81) and 14.3-42.9% (kappa=0), respectively, for conventional MR imaging. CONCLUSIONS: DWI is a useful sequence for identifying focal skull metastases for breast and lung malignancies and, compared with conventional MR imaging, provides improved detection of these lesions. DWI is insensitive for detecting skull metastases from prostate carcinoma.     

Localized prostate cancer: effect of hormone deprivation therapy measured by using combined three-dimensional 1H MR spectroscopy and MR imaging: clinicopathologic case-controlled study.

PURPOSE: To determine the accuracy of combined magnetic resonance (MR) imaging and three-dimensional (3D) proton MR spectroscopic imaging in localizing prostate cancer to a sextant of the gland in patients receiving hormone deprivation therapy. MATERIALS AND METHODS: Combined MR imaging/3D MR spectroscopic imaging examinations were performed in 16 hormone-treated patients and 48 nontreated matched control patients before radical prostatectomy and step-section histopathologic analysis. At MR imaging, cancer presence within the peripheral zone was assessed on a per sextant basis by two readers. At 3D MR spectroscopic imaging, cancer was identified by using (choline plus creatine)-to-citrate ratios at cutoff values of 2 and 3 SDs above mean normal peripheral zone values. Data were compared by using receiver operating characteristic analysis. RESULTS: There was no significant difference in the ability of combined MR imaging/3D MR spectroscopic imaging to localize prostate cancer in treated versus control patients. For MR imaging alone, the sensitivity and specificity were 91% and 48% (reader 1) and 75% and 60% (reader 2) in treated patients versus 79% and 60% (reader 1) and 84% and 43% (reader 2) in control patients. For 3D MR spectroscopic imaging alone (>3 SDs cutoff), higher specificity (treated, 80%; controls, 73%) but lower sensitivity (treated, 56%; controls, 53%) was attained. In treated patients, high sensitivity or specificity (up to 92%) was achieved when either or both modalities indicated cancer. CONCLUSION: When performed within 4 months after initiating hormone deprivation therapy, combined MR imaging/3D MR spectroscopic imaging had the same accuracy in localizing prostate cancer as in nontreated patients.     

Human breast lesions: characterization with contrast-enhanced in vivo proton MR spectroscopy--initial results.

PURPOSE: To assess the clinical usefulness of localized proton (hydrogen 1) magnetic resonance (MR) spectroscopy in the characterization of contrast material-enhanced breast lesions on the basis of choline detection. MATERIALS AND METHODS: Examinations were performed at 1.5 T with use of a standard breast coil. Contrast-enhanced MR imaging was performed in 30 consecutive patients (mean age, 50 years; age range, 20--80 years) who had nonspecific lesions (>1.5 cm in diameter) on sonograms or mammograms. Single-voxel (1)H MR spectroscopy was performed in the enhancing lesions by using a point-resolved spectroscopic sequence with echo times of 38, 135, and 270 msec. MR spectroscopic and histopathologic findings were determined in blinded fashion and compared. RESULTS: Twenty-four patients had carcinoma of the breast (tumor size, 2.0--11.2 cm; mean, 4.7 cm), and six had benign lesions (lesion size, 1.8--3.8 cm; mean, 2.7 cm). Choline was detected in 22 patients with carcinoma. Choline was not detected in five patients with benign lesions and in two patients with carcinoma. The preliminary results indicate that this technique had a sensitivity of 92%, specificity of 83%, and accuracy of 90%. CONCLUSION: Choline can be reliably detected in less than 45 minutes in large contrast-enhanced breast lesions by using a multiecho point-resolved spectroscopic protocol. The presence of water-soluble choline metabolites obtainable with (1)H MR spectroscopy could complement MR imaging findings to improve specificity and to reduce the number of unnecessary biopsies.     

Endorectal MR imaging and MR spectroscopic imaging for locally recurrent prostate cancer after external beam radiation therapy: preliminary experience

PURPOSE: To evaluate endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging for the depiction of locally recurrent prostate cancer after external beam radiation therapy. MATERIALS AND METHODS: Endorectal MR imaging and MR spectroscopic imaging were performed in 21 patients with biochemical failure after external beam radiation therapy for prostate cancer. Two readers independently and retrospectively reviewed MR images and rated the likelihood of recurrent tumor on a five-point scale. Spectroscopic voxels were considered suspicious for malignancy if the choline level was elevated and citrate was absent. Receiver operating characteristic curve analysis was used to assess cancer detection in each side of the prostate with endorectal MR imaging and spectroscopic imaging at different thresholds based on the scores assigned by the two readers and on the number of suspicious voxels in each hemiprostate, respectively. The presence or absence of cancer at subsequent transrectal biopsy was used as the standard of reference. RESULTS: Biopsy demonstrated locally recurrent prostate cancer in nine hemiprostates in six patients. The area under the receiver operating characteristic curve for the detection of locally recurrent cancer with MR imaging was 0.49 and 0.51 for readers 1 and 2, respectively. By using the number of suspicious voxels to define different diagnostic thresholds, the area under the receiver operating characteristic curve for MR spectroscopic imaging was significantly (P < .005) higher, at 0.81. In particular, the presence of three or more suspicious voxels in a hemiprostate showed a sensitivity and specificity of 89% and 82%, respectively, for the diagnosis of local recurrence. Seven hemiprostates demonstrated complete metabolic atrophy at spectroscopic imaging and only postirradiation atrophy at biopsy. CONCLUSION: Preliminary data suggest that MR spectroscopic imaging, but not endorectal MR imaging, may be of value for the depiction of locally recurrent prostate cancer after radiation therapy.     

Correlation of proton MR spectroscopic imaging with gleason score based on step-section pathologic analysis after radical prostatectomy

PURPOSE: To determine whether hydrogen 1 magnetic resonance (MR) spectroscopic imaging can be used to predict aggressiveness of prostate cancer. MATERIALS AND METHODS: All patients gave informed consent according to an institutionally approved research protocol. A total of 123 patients (median age, 58 years; age range, 40-74 years) who underwent endorectal MR imaging and MR spectroscopic imaging between January 2000 and December 2002 were included. MR imaging and spectroscopy were performed by using combined pelvic phased-array and endorectal probe. Water and lipids were suppressed, and phase-encoded data were acquired with 6.2-mm resolution. Voxels in the peripheral zone were considered suspicious for cancer if (Cho + Cr)/Cit was at least two standard deviations above the normal level, where Cho represents choline-containing compounds, Cr represents creatine and phosphocreatine, and Cit represents citrate. Correlation between metabolite ratio and four Gleason score groups identified at step-section pathologic evaluation (3 + 3, 3 + 4, 4 + 3, and > or =4 + 4) was assessed with generalized estimating equations. RESULTS: Data from 94 patients were included. Pathologic evaluation was used to identify 239 lesions. Overall sensitivity of MR spectroscopic imaging was 56% for tumor detection, increasing from 44% in lesions with Gleason score of 3 + 3 to 89% in lesions with Gleason score greater than or equal to 4 + 4. There was a trend toward increasing (Cho + Cr)/Cit with increasing Gleason score in lesions identified correctly with MR spectroscopic imaging. Tumor volume assessed with MR spectroscopic imaging increased with increasing Gleason score. CONCLUSION: MR spectroscopic imaging measurement of prostate tumor (Cho + Cr)/Cit and tumor volume correlate with pathologic Gleason score. There is overlap between MR spectroscopic imaging parameters at various Gleason score levels, which may reflect methodologic and physiologic variations. MR spectroscopic imaging has potential in noninvasive assessment of prostate cancer aggressiveness.     

Prostate cancer: local staging at 3-T endorectal MR imaging--early experience

PURPOSE: To prospectively investigate the local staging accuracy of 3-T endorectal magnetic resonance (MR) imaging for prostate cancer by using whole-mount-section histopathologic analysis as the standard of reference. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. In 35 consecutive patients (median age, 62.3 years) with biopsy-proved prostate cancer, 3-T endorectal MR imaging was performed. High-spatial-resolution endorectal T2-weighted fast spin-echo images of the prostate were obtained in three planes. MR images were prospectively evaluated by two experienced radiologists and a third radiologist who was less experienced with regard to local disease extent by using five established extracapsular criteria. Whole-mount-section histopathologic analysis was the standard of reference. Evaluation was performed according to octant and patient. Sensitivity, specificity, positive and negative predictive values, overall accuracy, and interobserver agreement were calculated. RESULTS: Thirty-two patients who underwent radical prostatectomy were enrolled in this study. Accuracy, sensitivity, and specificity of local staging were 94% (30 of 32), 88% (seven of eight), and 96% (23 of 24), respectively, for both experienced radiologists, and these values were 81% (26 of 32), 50% (four of eight), and 92% (22 of 24), respectively, for the less experienced radiologist. There was substantial agreement between both experienced readers (kappa = 0.42-0.79) and moderate agreement between the less experienced reader and the experienced readers with respect to all extracapsular criteria. In regard to the three cases of minimal capsular invasion, two were detected by both experienced radiologists. CONCLUSION: In this study, high accuracy for staging of prostate cancer at 3-T endorectal MR imaging, with moderate to substantial observer agreement, was demonstrated. In addition, minimal capsular invasion could be detected.     

Improved detection of focal liver lesions at MR imaging: multicenter comparison of gadoxetic acid-enhanced MR images with intraoperative findings

PURPOSE: To evaluate the safety and efficacy of gadoxetic acid disodium-enhanced magnetic resonance (MR) imaging for the detection of focal liver lesions, with results of histopathologic examination and/or intraoperative ultrasonography used as a standard of reference. MATERIALS AND METHODS: One hundred sixty-nine patients who were known to have or suspected of having focal liver lesions and were scheduled for liver surgery were included in this study. Results in 131 patients could be included in the efficacy analysis. MR imaging was performed before and immediately and 20 minutes after bolus injection of 0.025 mmol/kg of the liver-specific hepatobiliary contrast agent gadoxetic acid. T1-weighted gradient-echo (with and without fat saturation and including dynamic data sets) and T2-weighted fast spin-echo/turbo spin-echo sequences were performed. All images were evaluated on site and by three independent and blinded off-site reviewers. Lesion matching based on the standard-of-reference results was performed. Differences in lesion detection with precontrast and with postcontrast MR images were assessed with the two-sided Wilcoxon signed rank test. RESULTS: Gadoxetic acid was well tolerated. In the on-site review, the number of patients in whom all lesions were correctly matched increased from 89 of 129 patients at precontrast MR imaging to 103 of 129 patients at postcontrast MR imaging. In the off-site evaluation, the number of patients in whom all lesions were correctly matched and the corresponding sensitivity values increased from 72 (55.8%), 68 (52.7%), and 66 (51.2%) with the precontrast images to 88 (68.2%), 69 (53.5%), and 76 (58.9%) with the postcontrast images for readers 1, 2, and 3, respectively. Two of the three blinded readers showed a statistically significant difference in lesion detection between precontrast and postcontrast MR imaging (P <.001 and P =.008). A large number of additionally correctly detected and localized lesions were smaller than 1 cm. CONCLUSION: MR imaging with gadoxetic acid is safe and improves lesion detection and localization.     

Neuroimaging in pediatric brain tumors: Gd-DTPA-enhanced, hemodynamic, and diffusion MR imaging compared with MR spectroscopic imaging

BACKGROUND AND PURPOSE: Gadolinium-enhanced MR images assist in defining tumor borders; however, the relation between tumor cell extent and contrast-enhanced regions is unclear. Our aim was to improve conventional neuroimaging of pediatric brain tumors with hemodynamic, diffusion, and spectroscopic MR imaging. METHODS: We performed conventional MR and MR spectroscopic imaging in 31 children with neuroglial brain tumors. Hemodynamic MR imaging was performed in 16 patients with a first-pass intravenous bolus of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA); apparent diffusion coefficients (ADCs) were measured in 12 patients. To account for multiple measurements in a patient, we used a nested analysis of variance. RESULTS: At MR spectroscopy, choline (Cho)-containing compounds (indicating tumor) and lipid levels (indicating necrosis) did not correlate with percent Gd-DTPA enhancement on MR images. Percent enhancement was positively correlated with relative cerebral blood volumes (rCBVs) (P =.05) and negatively correlated with ADCs (P <.001). Stepwise multiple linear regression revealed that rCBV (P =.008), ADC (P =.022), and lipid (P <.001) levels were significant independent predictors of percent enhancement. Tumor spectral patterns were detected in tumor regions and outside enhancing tumor beds in patients with clinical progression; these were confirmed at neuropathologic analysis. CONCLUSION: MR spectroscopic imaging improves the assessment of pediatric brain tumors by adding biochemical information regarding tumor involvement and by depicting residual or recurrent tumor outside the Gd-DTPA-enhanced tumor bed. rCBV and ADC mapping complemented MR spectroscopic imaging. We recommend the use of MR spectroscopic imaging in addition to conventional MR imaging in assessing pediatric brain tumors.     

Periampullary tumors: high-spatial-resolution MR imaging and histopathologic findings in ampullary region specimens

PURPOSE: To prospectively determine the magnetic resonance (MR) signal intensity characteristics of structures of the ampullary region and to assess the potential use of MR imaging in evaluation of the extent of periampullary tumors in resected specimens. MATERIALS AND METHODS: Twenty-five specimens from the ampullary region obtained in four autopsy cases without periampullary tumors and in 21 patients with periampullary tumors were examined with a 1.5-T MR system and a circular surface coil with 5-inch (12.7-cm) diameter. High-spatial-resolution MR images were obtained with field of view of 100 x 100 mm, matrix of 256 x 256 or 512 x 256, and section thickness of 2 mm. MR imaging findings were compared with histopathologic findings. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissues were evaluated by two radiologists. RESULTS: T1- and T2-weighted MR images clearly depicted normal structures in the ampullary region that included Oddi muscle, duodenal wall, common bile duct, and pancreas; these findings corresponded well with histologic findings. In 20 (95%) of 21 tumors, high-spatial-resolution MR imaging depicted location and extension of periampullary tumors precisely. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissue were 88%, 100%, 96%, 100%, and 94%, respectively. CONCLUSION: In this study, MR imaging correctly depicted location, extension, and origin of tumor. High-spatial-resolution MR imaging has potential for presurgical staging of tumors in this region.     

MR imaging of the metacarpophalangeal joints of the fingers: part I. Conventional MR imaging and MR arthrographic findings in cadavers

PURPOSE: To demonstrate the normal anatomy of the metacarpophalangeal (MCP) joints of the fingers with magnetic resonance (MR) imaging and MR arthrography in cadavers. MATERIALS AND METHODS: MR images of 20 MCP joints of the fingers of five fresh human cadaveric hands in the extended and flexed positions were obtained before and after arthrography. The MR appearances of all articular and periarticular structures were analyzed and compared with those seen on anatomic sections. Two readers independently graded the visibility of these structures. Interobserver agreement was tested by using the kappa statistic. RESULTS: The main collateral ligaments could be best evaluated on the transverse images of flexed fingers. The accessory bands of the collateral ligament complex were best seen on the transverse images of extended fingers. Sagittal MR images were best for evaluating the palmar plate and the capsule. MR arthrography improved the visualization of all articular and periarticular structures. The kappa values related to conventional MR imaging findings at all sequences, 0.42-0.71, indicated moderate to substantial agreement. The kappa values for the MR arthrographic sequences, 0.59-0.74, were slightly higher than those for the nonenhanced sequences. CONCLUSION: Conventional MR imaging and MR arthrography enable accurate visualization of the important anatomic structures of the MCP joints. MR arthrography enhances visualization of the intraarticular elements.     

Prostate cancer: accurate determination of extracapsular extension with high-spatial-resolution dynamic contrast-enhanced and T2-weighted MR imaging--initial results

PURPOSE: To prospectively compare the sensitivity and specificity of high-spatial-resolution dynamic contrast material-enhanced magnetic resonance (MR) imaging with those of high-spatial-resolution T2-weighted MR imaging, performed with an endorectal coil (ERC), for assessment of extracapsular extension (ECE) and staging in patients with prostate cancer, with histopathologic findings as reference. MATERIALS AND METHODS: The study was approved by the institutional internal review board; a signed informed consent was obtained. MR imaging of the prostate at 1.5 T was performed with combined surface coils and ERCs in 32 patients (mean age, 65 years; range, 42-78 years) before radical prostatectomy. High-spatial-resolution T2-weighted fast spin-echo and high-spatial-resolution dynamic contrast-enhanced three-dimensional gradient-echo images were acquired with gadopentetate dimeglumine. Dynamic contrast-enhanced MR images were analyzed with a computer-generated color-coded scheme. Two experienced readers independently assessed ECE and tumor stage. MR imaging-based staging results were compared with histopathologic results. For the prediction of ECE, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Staging accuracy was determined with the area under the receiver operating characteristic curve (AUC) by using the Wilcoxon-Mann-Whitney index of diagnostic accuracy. RESULTS: The mean sensitivity, specificity, PPV, and NPV for assessment of ECE with the combined data sets for both readers were 86%, 95%, 90%, and 93%, respectively. The sensitivity of MR images for determination of ECE was significantly improved for both readers (>25%) with combined data sets compared with T2-weighted MR images alone. The combined data sets had a mean overall staging accuracy for both readers of 95%, as determined with AUC. Staging results for both readers were significantly improved (P<.05) with the combined data sets compared with T2-weighted MR images alone. CONCLUSION: The combination of high-spatial-resolution dynamic contrast-enhanced MR imaging and T2-weighted MR imaging yields improved assessment of ECE and better results for prostate cancer staging compared with either technique independently.     

Endorectal MR imaging before salvage prostatectomy: tumor localization and staging

PURPOSE: To evaluate retrospectively the accuracy of endorectal magnetic resonance (MR) imaging for the depiction of tumor, extracapsular extension (ECE), and seminal vesicle invasion (SVI) before salvage prostatectomy in patients with locally recurrent prostate cancer after radiation therapy, by using pathologic analysis as the reference standard. MATERIALS AND METHODS: The Institutional Review Board granted exempt status for this HIPAA-compliant study, with a waiver of informed consent. Forty-five consecutive patients (age range, 43-76 years) were identified who underwent salvage radical prostatectomy for prostate cancer at Memorial Sloan-Kettering Cancer Center between December 1, 1998, and October 31, 2004, and who underwent endorectal MR imaging prior to surgery. Tumor localization and determination of local stage with MR imaging were performed independently by two radiologists. Interpretations were compared to pathologic findings from surgical specimens. Interrater variability was estimated with the kappa statistic. Areas under the receiver operating characteristic curve (AUCs) were used to assess the accuracy of endorectal MR imaging in tumor detection and determination of ECE and SVI. RESULTS: Findings of histologic examination showed that tumor was present in all patients. For tumor detection, the AUC value for reader 1 was 0.75 (95% confidence interval [CI]: 0.67, 0.84), whereas the AUC value for reader 2 was 0.61 (95% CI: 0.52, 0.71). The AUC values for prediction of ECE were 0.87 (95% CI: 0.80, 0.94) for reader 1 and 0.76 (95% CI: 0.67, 0.85) for reader 2. The AUC values for prediction of SVI were 0.76 (95% CI: 0.62, 0.90) for reader 1 and 0.70 (95% CI: 0.56, 0.85) for reader 2. For all variables, the kappa statistics used to assess interrater agreement between readers were fair (0.45, 0.52, and 0.47 for tumor location, ECE, and SVI, respectively). CONCLUSION: Endorectal MR imaging following radiation therapy can help identify tumor sites and depict ECE and SVI with reasonable accuracy in patients with recurrent prostate cancer.