Diffusion-weighted magnetic resonance imaging: a potential non-invasive marker of tumour aggressiveness in localized prostate cancer

AIM: To evaluate diffusion-weighted magnetic resonance imaging (DW-MRI) as a marker for disease aggressiveness by comparing tumour apparent diffusion coefficients (ADCs) between patients with low- versus higher-risk localized prostate cancer. METHOD: Forty-four consecutive patients classified as low- [n = 26, stageT1/T2a, Gleason score < or = 6, prostate-specific antigen (PSA)< 10 (group 1)] or intermediate/high- [n = 18, stage > or = T2b and/or Gleason score > or = 7, and/or PSA > 10 (group 2)] risk, who subsequently were monitored with active surveillance or started neoadjuvant hormone and radiotherapy, respectively, underwent endorectal MRI. T2-weighted (T2W) and DW images (5 b values, 0-800 s/mm(2)) were acquired and isotropic ADC maps generated. Regions of interest (ROIs) on T2W axial images [around whole prostate, central gland (CG), and tumour] were transferred to ADC maps. Tumour, CG, and peripheral zone (PZ = whole prostate minus CG and tumour) ADCs (fast component from b = 0-100 s/mm(2), slow component from b = 100-800 s/mm(2)) were compared. RESULTS: T2W-defined tumour volume medians, and quartiles were 1.2 cm(3), 0.7 and 3.3 cm(3) (group 1); and 6 cm(3), 1.3 and 16.5 cm(3) (group 2). There were significant differences in both ADC(fast) (1778 +/- 264 x 10(-6) versus 1583 +/- 283 x 10(-6) mm(2)/s, p = 0.03) and ADC(slow) (1379 +/- 321 x 10(-6) versus 1196 +/- 158 x 10(-6) mm(2)/s, p = 0.001) between groups. Tumour volume (p = 0.002) and ADC(slow) (p = 0.005) were significant differentiators of risk group. CONCLUSION: Significant differences in tumour ADCs exist between patients with low-risk, and those with higher-risk localized prostate cancer. DW-MRI merits further study with respect to clinical outcomes.     

Prostate cancer detection with 3-T MRI: comparison of diffusion-weighted and T2-weighted imaging

OBJECTIVE: To compare the clinical value of diffusion-weighted (DW) and T2-weighted (T2W) imaging in detecting prostate cancer using a 3-Tesla (3T) magnetic resonance (MR) system. MATERIALS AND METHODS: Thirty-seven patients with suspected prostate cancer underwent T2W and DW imaging at 3T using an 8-channel phased-array coil. These images and apparent diffusion coefficient (ADC) maps were read retrospectively and blindly. The results were compared with histopathologic findings, and receiver operating characteristic (ROC) analysis was used to compare the cancer detection performance of T2W and DW imaging. RESULTS: The areas under the ROC curves for DW imaging and T2W imaging were 0.89 and 0.82, respectively. The performance of DW imaging in prostate cancer detection was significantly better than that of T2W imaging (P=0.0371). CONCLUSION: With a 3T MR system, the performance of DW imaging in detecting prostate cancer was better than that of T2W imaging. DW imaging appears to be a robust and reliable method to examine the whole prostate within an acceptable scan time in clinical settings.     

Diffusion-weighted imaging of prostate cancer

OBJECTIVE: The purpose of this study was to assess whether T2-weighted (T2W) imaging with diffusion-weighted (DW) imaging could improve prostate cancer detection as compared with T2W imaging alone. METHODS: The subjects consisted of 37 patients with prostate cancer and 23 without cancer undergoing magnetic resonance (MR) imaging. Using a 1.5-T superconducting magnet, all patients underwent T2W and DW imaging with parallel imaging. Images were independently reviewed by 3 readers to determine the detectability of prostate cancer. The detectability of T2W imaging without and with DW imaging was assessed by means of receiver operating characteristic analysis. RESULTS: Mean areas under the receiver operating characteristic curve for T2W imaging alone and for T2W imaging with DW imaging were 0.87 and 0.93, respectively. The receiver operating characteristic analysis showed that the addition of DW imaging to conventional T2W imaging significantly improved tumor detection (P = 0.0468) compared with T2W imaging alone. CONCLUSIONS: The addition of DW imaging to conventional T2W imaging provides better detection of prostate cancer.     

Prediction of locally recurrent prostate cancer after radiation therapy: Incremental value of 3T diffusion‐weighted MRI

Purpose

To prospectively evaluate the incremental value of diffusion‐weighted imaging (DWI) with apparent diffusion coefficient (ADC) maps in addition to T2‐weighted imaging (T2WI) for predicting locally recurrent prostate cancer in patients with biochemical failure after radiation therapy.

Materials and Methods

Thirty‐six consecutive patients with an increased prostate‐specific antigen level after radiation therapy underwent 3T MRI followed by transrectal biopsy. The MRI findings and biopsy results were correlated in sextant prostate sectors of peripheral zones (PZs). Two radiologists in consensus reviewed T2WI and combined T2WI and DWI with ADC maps, and rated the likelihood of recurrent cancer on a five‐point scale. ADC values were calculated for recurrent cancer and benign tissue.

Results

Of 216 sectors, 65 prostate sectors (30%) were positive for cancer in 18 patients. For predicting recurrent cancer, combined T2WI and DWI showed a greater sensitivity compared to T2WI (P < 0.001). A significantly greater area under the receiver operating characteristics curve (Az) was determined for combined T2WI and DWI (Az = 0.879, P < 0.01) as compared to T2WI (Az = 0.612). Mean ADC values between recurrent cancer and benign tissue showed a statistically significant difference (P < 0.01).

Conclusion

For predicting locally recurrent prostate cancer after radiation therapy, the use of combined T2WI and DWI showed a better diagnostic performance compared to T2WI. J. Magn. Reson. Imaging 2009;29:391–397. © 2009 Wiley‐Liss, Inc.     

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.     

Diffusion-weighted MR imaging of abdominopelvic abscesses

This study was conducted to determine the incremental value of diffusion-weighted MR imaging (DW-MRI) over T2-weighted imaging diagnosing abdominopelvic abscesses and compare apparent diffusion coefficient (ADC) values of abscesses and non-infected ascites. In this IRB-approved, HIPAA-compliant study, two radiologists retrospectively compared T2-weighted, T2-weighted + DW-MRI and T2-weighted + contrast enhanced MR images of 58 patients (29 with abscess, 29 with ascites) who underwent abdominal MRI for abscess detection. Confidence and sensitivity was compared using McNemar’s test. ADC of abscesses and ascites was compared by t test, and a receiver operating characteristic (ROC) curve was constructed. Detection of abscesses and confidence improved significantly when T2-weighted images were combined with DW-MRI (sensitivity: observer 1—100%, observer 2—96.6%) or contrast enhanced images (sensitivity: both observers—100%) compared to T2-weighted images alone (sensitivity: observer 1—65.5%, observer 2—72.4%). All abscesses showed restricted diffusion. Mean ADC of abscesses (observer 1—1.17 ± 0.42 × 10⁻3 mm2/s, observer 2—1.43 ± 0.48 × 10⁻³ mm2/s) was lower than ascites (observer 1—3.57 ± 0.68 × 10⁻³ mm2/s, observer 2—3.42 ± 0.67 × 10⁻³ mm2/s) (p < 0.01). ROC analysis showed perfect discrimination of abscess from ascites with threshold ADC of 2.0 × 10⁻³ mm2/s (Az value 1.0). DW-MRI is a valuable adjunct to T2-weighted images diagnosing abdominopelvic abscesses. ADC measurements may have the potential to differentiate abdominal abscesses from ascites.     

Prostate cancer: correlation of MR imaging and MR spectroscopy with pathologic findings after radiation therapy-initial experience

PURPOSE: To prospectively evaluate magnetic resonance (MR) imaging and MR spectroscopy for depiction of local prostate cancer recurrence after external-beam radiation therapy, with step-section pathologic findings as the standard of reference. MATERIALS AND METHODS: Study received institutional approval, and written informed consent was obtained. Study was compliant with Health Insurance Portability and Accountability Act. Sextant biopsy, digital rectal examination, MR imaging, MR spectroscopy, and salvage radical prostatectomy with step-section pathologic examination were performed in nine patients with increasing prostate-specific antigen levels after external-beam radiation therapy. MR imaging criterion for tumor was a focal nodular region of reduced signal intensity at T2-weighted imaging. MR spectroscopic criteria for tumor were voxels with choline (Cho) plus creatine (Cr) to citrate (Cit) ratio ([Cho + Cr]/Cit) of at least 0.5 or voxels with detectable Cho and no Cit in the peripheral zone. Sensitivity and specificity of sextant biopsy, digital rectal examination, MR imaging, and MR spectroscopy were determined by using a prostate sextant as the unit of analysis. For feature analysis, MR imaging and MR spectroscopic findings were correlated with step-section pathologic findings. RESULTS: MR imaging and MR spectroscopy showed estimated sensitivities of 68% and 77%, respectively, while sensitivities of biopsy and digital rectal examination were 48% and 16%, respectively. MR spectroscopy appears to be less specific (78%) than the other three tests, each of which had a specificity higher than 90%. MR spectroscopic feature analysis showed that a metabolically altered benign gland could be falsely identified as tumor by using MR spectroscopic criteria; further analysis of MR spectroscopic features did not lead to improved MR spectroscopic criteria for recurrent tumor. CONCLUSION: In summary, MR imaging and MR spectroscopy may be more sensitive than sextant biopsy and digital rectal examination for sextant localization of cancer recurrence after external-beam radiation therapy.     

Diagnostic performance of diffusion-weighted magnetic resonance imaging in bladder cancer: potential utility of apparent diffusion coefficient values as a biomarker to predict clinical aggressiveness

Objectives

The diagnostic performance of diffusion-weighted magnetic resonance imaging (DW-MRI) in bladder cancer and the potential role of apparent diffusion coefficient (ADC) values in predicting pathological bladder cancer phenotypes associated with clinical aggressiveness were investigated.

Methods

One hundred and four bladder cancer patients underwent DW-MRI and T2-weighted magnetic resonance imaging (T2W-MRI) before transurethral resection. The image sets were reviewed by two independent radiologists. ADC values were measured in 121 eligible tumours.

Results

In detecting patients with bladder cancer, DW-MRI exhibited high sensitivity equivalent to that of T2W-MRI (>90%). Interobserver agreement was excellent for DW-MRI (κ score, 0.88) though moderate for T2W-MRI (0.67). ADC values were significantly lower in high-grade (vs. low-grade, P?P?Conclusion DW-MRI exhibits high diagnostic performance in bladder cancer with excellent objectivity. The ADC value could potentially serve as a biomarker to predict clinical aggressiveness in bladder cancer.     

Value of diffusion-weighted imaging for the prediction of prostate cancer location at 3T using a phased-array coil: preliminary results

OBJECTIVES: To retrospectively evaluate the imaging quality of diffusion-weighted imaging (DWI), compare the apparent diffusion coefficient (ADC) values for malignant and benign tissues in the peripheral zone (PZ) and transition zone (TZ), and evaluate whether T2-weighted imaging (T2WI) with DWI could improve the prediction of prostate cancer location when compared with T2WI at 3T using a phased-array coil. MATERIALS AND METHODS: Thirty-seven patients underwent T2WI and DWI before radical prostatectomy. The DWI technique with b = 0 and b = 1000 s/mm2 was used. ADC values were measured in benign and malignant tissues in the PZ or TZ. The prediction of prostate cancer location was evaluated in the PZ and TZ using T2WI and T2WI with DWI, respectively. Two readers in consensus recorded the presence of prostate cancer at magnetic resonance imaging and rated the imaging quality of DWI. RESULTS: For the prediction of 68 prostate tumors, the overall sensitivity and positive predictive value of T2WI with DWI were 84% and 86%, whereas those of T2WI were 66% and 63%, respectively (P < 0.05). The mean ADC values of malignant and benign tissues in the PZ and TZ were 1.30 +/- 0.26 and 1.96 +/- 0.20, and 1.35 +/- 0.24 and 1.75 +/- 0.23 x 10(-3)mm2/s, respectively (P < 0.01). The overall imaging quality was satisfactory or better in 97% of patients. CONCLUSION: DWI is a feasible technique that can be used for the differentiation of malignant and benign tissues in the PZ and TZ. Additionally, T2WI with DWI is superior to T2WI alone for the prediction of prostate cancer location.     

Usefulness of apparent diffusion coefficient map in diagnosing prostate carcinoma: correlation with stepwise histopathology

PURPOSE: To elucidate the performance of apparent diffusion coefficient (ADC) map in localizing prostate carcinoma (PC) using stepwise histopathology as a reference. MATERIALS AND METHODS: Preoperative MR images of 37 patients with PC who had undergone radical prostatectomy were retrospectively evaluated. First, T2-weighted images (T2WI) alone were interpreted (T2WI reading), and then T2WI along with ADC map were interpreted (T2WI/ADC map reading). Sextant-based sensitivity and specificity, and the ratio of the detected volume to the whole tumor volume (% tumor volume) were compared between the two interpretations, and results were also correlated to Gleason's scores (GS). ADC values were correlated to histological grades. RESULTS: Sensitivity was significantly higher in T2WI/ADC map reading than in T2WI reading (71% vs. 51%), but specificity was similar (61% vs. 60%). By adding ADC map to T2WI, % tumor volume detected increased significantly in transitional zone (TZ) lesions, but not in peripheral zone (PZ) lesions. % tumor volume detected with T2WI/ADC map reading showed a positive correlation with GS of the specimens. Less differentiated PC were associated with lower ADC values and higher detectability. CONCLUSION: T2WI/ADC map reading was better than T2WI reading in PC detection and localization. This approach may be particularly useful for detecting TZ lesions and biologically aggressive lesions.     

Predictors of prostate carcinoma: accuracy of gray-scale and color Doppler US and serum markers

PURPOSE: To determine the accuracy of detecting prostate cancer by using (a) gray-scale and color Doppler transrectal ultrasonography (US), (b) serum and excess prostate-specific antigen (PSA) levels, and (c) targeted and sextant transrectal US-guided biopsy. The relationship between US-detected neovascularity and tumor biologic activity was also evaluated. MATERIALS AND METHODS: Between 1995 and 1999, 544 patients with elevated PSA levels and/or abnormal digital rectal examination underwent transrectal US-guided sextant biopsy and targeted biopsy of US abnormalities. Sensitivity, specificity, and accuracy of gray-scale US, color Doppler US, targeted biopsy, and PSA and excess PSA were calculated. RESULTS: Gray-scale US depicted 78 (41.1%) of 190 cancers, whereas color Doppler US depicted 30 (15.8%) additional cancers. Targeted biopsy was used to detect 108 (56.8%) cancers, whereas sextant biopsy was used to detect 82 (43.2%) additional cancers. Although US-visible cancers had a higher Gleason grade than did cancers discovered at sextant biopsy (P <.05), 25 of the 66 cancers identified with sextant biopsy alone were Gleason grade 6 or higher. Color Doppler US-depicted hypervascularity correlated with biologically aggressive tumors. Excess PSA was normal in 58 (30.5%) cancers, with an accuracy of 67.3%, resulting in better prediction of prostate tumors than with serum PSA level alone. CONCLUSION: Gray-scale transrectal US, even coupled with color Doppler US, is inadequate for prostate carcinoma screening; therefore, targeted biopsy should always be accompanied by complete sextant biopsy sampling.     

Diffusion-weighted imaging of normal and malignant prostate tissue at 3.0T

PURPOSE: To measure the apparent diffusion coefficient (ADC) of normal and malignant prostate tissue at 3.0T using a phased-array coil and parallel imaging, and determine the utility of ADC values in differentiating tumor from normal peripheral zone (PZ). MATERIALS AND METHODS: ADC values were calculated for 49 patients (tumor and PZ) with evidence of prostate cancer. Additionally, for nine asymptomatic volunteers, ADC values were determined for apparently normal central gland and PZ. A single-shot EPI diffusion-weighted imaging (DWI) technique with b = 0 and 500 seconds/mm2 was employed. RESULTS: ADC values were significantly lower for tumor (1.38 +/- 0.32 x 10(-3) mm2/second) than for patient PZ (1.95 +/- 0.50 x 10(-3) mm2/second, P < 0.001) and volunteer PZ (1.60 +/- 0.25 x 10(-3) mm2/second, P = 0.031). A considerable overlap of ADC values was noted between patient tissue types. CONCLUSION: DWI of the prostate at 3.0T in conjunction with a phased-array coil and parallel imaging allows ADC calculation of the prostate. ADC values were lower for tumors compared to normal-appearing PZ; however, there was considerable intersubject variability.     

Prostate cancer: sextant localization with MR imaging, MR spectroscopy, and 11C-choline PET/CT

PURPOSE: To retrospectively compare sensitivity and specificity of magnetic resonance (MR) imaging, three-dimensional (3D) MR spectroscopy, combined MR imaging and 3D MR spectroscopy, and carbon 11 (11C)-choline positron emission tomography (PET)/computed tomography (CT) for intraprostatic tumor sextant localization, with histologic findings as reference standard. MATERIALS AND METHODS: The local ethics committee on human research provided approval and a waiver of informed consent for the retrospective study. MR imaging, 3D MR spectroscopy, and 11C-choline PET/CT results were retrospectively reviewed in 26 men with biopsy-proved prostate cancer (mean age, 64 years; range, 51-75 years) who underwent radical prostatectomy. Cancer was identified as areas of nodular low signal intensity on T2-weighted MR images. At 3D MR spectroscopy, choline-plus-creatine-to-citrate and choline-to-creatine ratios were used to distinguish healthy from malignant voxels. At PET/CT, focal uptake was visually assessed, and maximum standardized uptake values (SUVs) were recorded. Agreement between 3D MR spectroscopic and PET/CT results was calculated, and ability of maximum SUV to help localize cancer was assessed with receiver operating characteristic analysis. Significant differences between positive and negative sextants with respect to mean maximum SUV were calculated with a paired t test. RESULTS: Sensitivity, specificity, and accuracy were, respectively, 55%, 86%, and 67% at PET/CT; 54%, 75%, and 61% at MR imaging; and 81%, 67%, and 76% at 3D MR spectroscopy. The highest sensitivity was obtained when either 3D MR spectroscopic or MR imaging results were positive (88%) at the expense of specificity (53%), while the highest specificity was obtained when results with both techniques were positive (90%) at the expense of sensitivity (48%). Concordance between 3D MR spectroscopic and PET/CT findings was slight (kappa=0.139). CONCLUSION: In localizing cancer within the prostate, comparable specificity was obtained with either 3D MR spectroscopy and MR imaging or PET/CT; however, PET/CT had lower sensitivity relative to 3D MR spectroscopy alone or combined with MR imaging.     

Prostate cancer vs. post‐biopsy hemorrhage: Diagnosis with T2‐ and diffusion‐weighted imaging

Purpose:

To assess the value of quantitative T2 signal intensity (SI) and apparent diffusion coefficient (ADC) to differentiate prostate cancer from post‐biopsy hemorrhage, using prostatectomy as the reference.

Materials and Methods:

Forty‐five men with prostate cancer underwent prostate magnetic resonance imaging (MRI), including axial T1‐weighted imaging (T1WI), T2WI, and single‐shot echo‐planar image (SS EPI) diffusion‐weighted imaging. Two observers measured, in consensus, normalized T2 signal intensity (SI) (nT2, relative to muscle T2 SI), ADC, and normalized ADC (nADC, relative to urine ADC) on peripheral zone (PZ) tumors, benign PZ hemorrhage, and non‐hemorrhagic benign PZ. Tumor maps from prostatectomy were used as the reference. Mixed model analysis of variance was performed to compare parameters among the three tissue classes, and Pearson's correlation coefficient was utilized to assess correlation between parameters and tumor size and Gleason score. Receiver‐operating characteristic (ROC)‐curve analysis was used to determine the performance of nT2, ADC, and nADC for diagnosis of prostate cancer.

Results:

nT2, ADC, and nADC were significantly lower in tumor compared with hemorrhagic and non‐hemorrhagic benign PZ (P < 0.0001). There was a weak but significant correlation between ADC and Gleason score (r = ?0.30, P = 0.0119), and between ADC and tumor size (r = ?0.40, P = 0.0027), whereas there was no correlation between nT2 and Gleason score and tumor size. The areas under the curve to distinguish tumor from benign hemorrhagic and non‐hemorrhagic PZ were 0.97, 0.96, and 0.933 for nT2, ADC, and nADC, respectively.

Conclusion:

Quantitative T2 SI and ADC/nADC values may be used to reliably distinguish prostate cancer from post‐biopsy hemorrhage. J. Magn. Reson. Imaging 2010;31:1387–1394. © 2010 Wiley‐Liss, Inc.

     

The value of diffusion-weighted imaging in combination with T2-weighted imaging for rectal cancer detection

OBJECTIVE: To evaluate the clinical value of diffusion-weighted imaging (DWI) in combination with T(2)-weighted imaging (T(2)WI) for the detection of rectal cancer as compared with T(2)WI alone. MATERIALS AND METHODS: Forty-five patients with rectal cancer and 20 without rectal cancer underwent DWI with parallel imaging and T(2)WI on a 1.5 T scanner. Images were independently reviewed by two readers blinded to the results to determine the detectability of rectal cancer. The detectability of T(2)W imaging without and with DW imaging was assessed by means of receiver operating characteristic analysis. The interobserver agreement between the two readers was calculated with kappa statistics. RESULTS: The ROC analysis showed that each of two readers achieved more accurate results with T(2)W imaging combined with DW imaging than with T(2)W imaging alone significantly. The A(z) values for the two readers for each T(2)WI and T(2)WI combined with DWI were 0.918 versus 0.991 (p=0.0494), 0.934 versus 0.997 (p=0.0475), respectively. The values of kappa were 0.934 for T(2)WI and 0.948 for T(2)WI combined with DWI between the two readers. CONCLUSION: The addition of DW imaging to conventional T(2)W imaging provides better detection of rectal cancer.     

PI-RADS 3 Lesions: Role of Prostate MRI Texture Analysis in the Identification of Prostate Cancer

PurposeTo determine the diagnostic performance of texture analysis of prostate MRI for the diagnosis of prostate cancer among Prostate Imaging Reporting and Data System (PI-RADS) 3 lesions.Materials and MethodsForty-three patients with at least 1 PI-RADS 3 lesion on prostate MRI performed between June 2016 and January 2019 were retrospectively included. Reference standard was pathological analysis of radical prostatectomy specimens or MRI-targeted biopsies. Texture analysis extraction of target lesions was performed on axial T2-weighted images and apparent diffusion coefficient (ADC) maps using a radiomic software. Lesions were categorized as prostate cancer (Gleason score [GS] ≥ 6), and no prostate cancer. Statistical analysis was performed using the generalized linear model (GLM) regression and the discriminant analysis (DA). AUROC with 95% confidence intervals were calculated to assess the diagnostic performance of standalone features and predictive models for the diagnosis of prostate cancer (GS ≥ 6) and clinically-significant prostate cancer (GS ≥ 7).ResultsThe analysis of 46 PI-RADS 3 lesions (ie, 27 [58.7%] no prostate cancers; 19 [41.3%] prostate cancers) revealed 9 and 6 independent texture parameters significantly correlated with the final histopathological results on T2-weighted and ADC maps images, respectively. The resulting GLM and DA predictive models for the diagnosis of prostate cancer yielded an AUROC of 0.775 and 0.779 on T2-weighted images or 0.815 and 0.821 on ADC maps images. For the diagnosis of clinically-significant prostate cancer, the resulting GLM and DA predictive models for the diagnosis of prostate cancer yielded an AUROC of 0.769 and 0.817 on T2-weighted images or 0.749 and 0.744 on ADC maps images.ConclusionTexture analysis of PI-RADS 3 lesions on T2-weighted and ADC maps images helps identifying prostate cancer. The good diagnostic performance of the combination of multiple radiomic features for the diagnosis of prostate cancer may help predicting lesions where aggressive management may be warranted.     

Prostate cancer screening: the clinical value of diffusion-weighted imaging and dynamic MR imaging in combination with T2-weighted imaging

PURPOSE: To evaluate the clinical value of diffusion-weighted imaging (DWI) and dynamic MRI in combination with T2-weighted imaging (T2W) for the detection of prostate cancer. MATERIALS AND METHODS: A total of 83 patients with elevated serum prostate specific antigen (PSA) levels (>4.0 ng/mL) were evaluated by T2W, DWI, and dynamic MRI at 1.5 T prior to needle biopsy. The data from the results of the T2W alone (protocol A), combination of T2W and DWI (protocol B), and the combination of T2W+DWI and dynamic MRI (protocol C) were entered into a receiver operating characteristic (ROC) curve analysis, under results of systemic biopsy as the standard of reference. RESULTS: Prostate cancer was pathologically detected in 44 of the 83 patients. The sensitivity, specificity, accuracy, and the area under the ROC curve (Az) for the detection of prostate cancer were as follows: 73%, 54%, 64%, and 0.711, respectively, in protocol A; 84%, 85%, 84%, and 0.905, respectively, in protocol B; and 95%, 74%, 86%, and 0.966, respectively, in protocol C. The sensitivity, specificity, and accuracy were significantly different between the three protocols (P < 0.01). CONCLUSION: In patients with elevated serum PSA levels, the combination of T2W, DWI, and dynamic MRI may be a valuable tool for detecting prostate cancer and avoiding an unnecessary biopsy without missing prostate cancer.     

Rectal cancer: MR imaging in local staging--is gadolinium-based contrast material helpful?

PURPOSE: To determine retrospectively whether addition of gadolinium-enhanced T1-weighted magnetic resonance (MR) sequence to T2-weighted turbo spin-echo (SE) MR imaging is valuable for preoperative assessment of T stage and circumferential resection margin in patients with primary rectal cancer. MATERIALS AND METHODS: Local institutional review board approved study and waived informed patient consent. Eighty-three patients with operable primary rectal cancer underwent preoperative MR imaging. Retrospectively, two observers independently scored T2-weighted turbo SE MR images and, in a second reading, T2-weighted images combined with gadolinium-enhanced T1-weighted turbo SE MR images for tumor penetration through rectal wall and tumor extension into mesorectal fascia. A confidence level scoring system was used, and receiver operating characteristic (ROC) curves were generated. Histologic findings were standard of reference. Difference in performance of T2-weighted and combined T2-weighted plus gadolinium-enhanced T1-weighted sequences was analyzed by comparing corresponding areas under ROC curves (A(z)) for each observer. Interobserver agreement was calculated by using linear weighted kappa statistics. RESULTS: Addition of contrast-enhanced T1-weighted to T2-weighted MR imaging did not significantly improve diagnostic accuracy for prediction of tumor penetration through rectal wall (A(z) of T2-weighted vs T2-weighted plus T1-weighted images for observer 1, 0.740 vs 0.764; observer 2, 0.856 vs 0.768) and tumor extension into mesorectal fascia (A(z) for observer 1, 0.962 vs 0.902; observer 2, 0.902 vs 0.911). Diagnostic performance (A(z)) of MR and interobserver agreement were high for prediction of tumor extension into mesorectal fascia (kappa = 0.61, 0.74) but only moderate for penetration through rectal wall (kappa = 0.47, 0.45). CONCLUSION: Gadolinium-enhanced MR sequences did not improve diagnostic accuracy for assessment of tumor penetration through rectal wall and tumor extension into mesorectal fascia.     

High-resolution MRI of excised human prostate specimens acquired with 9.4T in detection and identification of cancers: validation of a technique

Purpose:

To evaluate feasibility of high‐resolution, high‐field ex vivo prostate magnetic resonance imaging (MRI) as an aid to guide pathologists' examination and develop in vivo MRI methods.

Materials and Methods:

Unfixed excised prostatectomy specimens (n = 9) were obtained and imaged immediately after radical prostatectomy under an Institutional Review Board‐approved protocol. High‐resolution T2‐weighted (T2W) MRI of specimens were acquired with a Bruker 9.4 T scanner to correlate with whole‐mount histology. Additionally, T2 and apparent diffusion coefficient (ADC) maps were generated.

Results:

By visual inspection of the nine prostate specimens imaged, high‐resolution T2W MRI showed improved anatomical detail compared to published low‐resolution images acquired at 4 T as published by other investigators. Benign prostatic hyperplasia, adenocarcinomas, curvilinear duct architecture distortion due to adenocarcinomas, and normal radial duct distribution were readily identified. T2 was ≈10 msec longer (P < 0.03) and the ADC was ≈1.4 times larger (P < 0.002) in the normal peripheral zone compared to the peripheral zone with prostate cancer.

Conclusion:

Differences in T2 and ADC between benign and malignant tissue are consistent with in vivo data. High‐resolution, high‐field MRI has the potential to improve the detection and identification of prostate structures. The protocols and techniques developed in this study could augment routine pathological analysis of surgical specimens and guide treatment of prostate cancer patients. J. Magn. Reson. Imaging 2011. © 2011 Wiley‐Liss, Inc.     

The role of diffusion – Weighted MRI in evaluation of prostate cancer

The aim of work

To illustrate the role of T2WI combined with diffusion WI (DWI) in the evaluation of patients with prostate cancer.

Patients and methods

This prospective study included 36 patients (mean age 61) with clinical suspicion of prostate cancer using surface coil at 1.5 T MR Unit. Axial, coronal, and sagittal high resolution (HR) T2WI were performed, DWI was applied using a single-shot echo-planar imaging sequence in axial orientation. Regions of interest were drawn on ADC maps on the site of visible restricted diffusion as well as the normal tissue, then the ADC value was calculated. Considering histopathological diagnosis the standard of reference, the results of T2WI alone were compared with those of combined T2WI and DWI.

Results

In this prospective study, 36 men were examined and T2WI, DWI, ADC map and ADC values were measured. T2 low SI was detected in the peripheral zone of the prostate of 36 patients, and restricted diffusion in 31 patients.

Conclusion

Our study indicates that the addition of the ADC map and DWI to T2WI provide significantly more accurate results for prostate cancer detection and staging.