Prostate cancer detection with 3 T MRI: Comparison of diffusion‐weighted imaging and dynamic contrast‐enhanced MRI in combination with T2‐weighted imaging

Purpose:

To evaluate the diagnostic ability of diffusion‐weighted imaging (DWI) and dynamic contrast‐enhanced imaging (DCEI) in combination with T2‐weighted imaging (T2WI) for the detection of prostate cancer using 3 T magnetic resonance imaging (MRI) with a phased‐array body coil.

Materials and Methods:

Fifty‐three patients with elevated serum levels of prostate‐specific antigen (PSA) were evaluated by T2WI, DWI, and DCEI prior to needle biopsy. The obtained data from T2WI alone (protocol A), a combination of T2WI and DWI (protocol B), a combination T2WI and DCEI (protocol C), and a combination of T2WI plus DWI and DCEI (protocol D) were subjected to receiver operating characteristic (ROC) curve analysis.

Results:

The sensitivity, specificity, accuracy, and area under the ROC curve (Az) for region‐based analysis were: 61%, 91%, 84%, and 0.8415, respectively, in protocol A; 76%, 94%, 90%, and 0.8931, respectively, in protocol B; 77%, 93%, 89%, and 0.8655, respectively, in protocol C; and 81%, 96%, 92%, and 0.8968, respectively in protocol D. ROC analysis revealed significant differences between protocols A and B (P = 0.0008) and between protocols A and D (P = 0.0004).

Conclusion:

In patients with elevated PSA levels the combination of T2WI, DWI, DCEI using 3 T MRI may be a reasonable approach for the detection of prostate cancer. J. Magn. Reson. Imaging 2010;31:625–631. © 2010 Wiley‐Liss, Inc.     

Combined T2‐weighted and diffusion‐weighted MRI for diagnosis of urinary bladder invasion in patients with prostate carcinoma

Purpose

To retrospectively determine the diffusion‐weighted imaging (DWI) characteristics and apparent diffusion coefficient (ADC) values of prostate carcinoma (PCa) with urinary bladder invasion, and to compare the accuracy of T2‐weighted MRI alone and T2 combined with DWI for predicting urinary bladder invasion.

Materials and Methods

Sixty‐eight patients with proven PCa were diagnosed with urinary bladder invasion after conventional magnetic resonance imaging (MRI) and DWI (b value = 750 sec/mm²) examinations. All the 68 cases underwent cystoscopy examination. DWI appearances of all urinary bladder invasion and a normal urinary bladder wall were analyzed, and their ADC values were measured. T2 images alone and then T2 images combined with DWI were scored for the likelihood of urinary bladder invasion on the basis of radiologists' written reports. The area under the receiver operating characteristic curve (AUC) was used to assess accuracy. Statistical significance was inferred at P < 0.05.

Results

After cystoscopy examination, 45 (66%) of 68 cases were pathologically proven urinary bladder invasion. The mean ADCs for urinary bladder invasion and normal urinary bladder wall were (0.963 ± 0.155) × 10^?3mm²/sec and (1.517 ± 0.103) × 10^?3mm²/sec, respectively. The ADC values of urinary bladder invasion were significantly lower than those of normal urinary bladder wall (P = 0.000). The AUC for T2‐weighted imaging plus DW imaging (0.861) was significantly larger than that for T2‐weighted imaging alone (0.734) or for DW imaging alone (0.703) (P < 0.001).

Conclusion

Urinary bladder invasion had lower ADC values compared with normal urinary bladder wall. T2 images plus DWI is significantly better than T2‐weighted imaging alone in the detection of urinary bladder invasion in patients with PCa. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.

     

Prostate cancer detection with multi‐parametric MRI: Logistic regression analysis of quantitative T2, diffusion‐weighted imaging,and dynamic contrast‐enhanced MRI

Purpose

To develop a multi‐parametric model suitable for prospectively identifying prostate cancer in peripheral zone (PZ) using magnetic resonance imaging (MRI).

Materials and Methods

Twenty‐five radical prostatectomy patients (median age, 63 years; range, 44–72 years) had T2‐weighted, diffusion‐weighted imaging (DWI), T2‐mapping, and dynamic contrast‐enhanced (DCE) MRI at 1.5 Tesla (T) with endorectal coil to yield parameters apparent diffusion coefficient (ADC), T2, volume transfer constant (K^trans) and extravascular extracellular volume fraction (v_e). Whole‐mount histology was generated from surgical specimens and PZ tumors delineated. Thirty‐eight tumor outlines, one per tumor, and pathologically normal PZ regions were transferred to MR images. Receiver operating characteristic (ROC) curves were generated using all identified normal and tumor voxels. Step‐wise logistic‐regression modeling was performed, testing changes in deviance for significance. Areas under the ROC curves (A_z) were used to evaluate and compare performance.

Results

The best‐performing single‐parameter was ADC (mean A_z [95% confidence interval]: A_z,ADC: 0.689 [0.675, 0.702]; A_z,T2: 0.673 [0.659, 0.687]; A_z,Ktrans: 0.592 [0.578, 0.606]; A_z,ve: 0.543 [0.528, 0.557]). The optimal multi‐parametric model, LR‐3p, consisted of combining ADC, T2 and K^trans. Mean A_z,LR‐3p was 0.706 [0.692, 0.719], which was significantly higher than A_z,T2, A_z,Ktrans, and A_z,ve (P < 0.002). A_z,LR‐3p tended to be greater than A_z,ADC, however, this result was not statistically significant (P = 0.090).

Conclusion

Using logistic regression, an objective model capable of mapping PZ tumor with reasonable performance can be constructed. J. Magn. Reson. Imaging 2009;30:327–334. © 2009 Wiley‐Liss, Inc.     

Diffusion‐weighted imaging of prostate cancer: Correlation between apparent diffusion coefficient values and tumor proliferation

Purpose

To investigate whether the apparent diffusion coefficient (ADC) values of prostate cancer (PCa) are able to reflect tumor proliferation.

Materials and Methods

The clinical and pathological information for 38 patients with PCa and 33 patients with benign prostate hyperplasia (BPH) were studied. Examination of the patients was performed using a 1.5 T superconducting magnetic scanner equipped with a pelvic phased‐array multicoil. Diffusion‐weighted images (DWIs) were acquired using an echo‐planar imaging sequence. The ADC values of PCa, BPH, and peripheral zone (PZ) were calculated. The cellularity of PCa was recorded based on hematoxylin and eosin staining. The proliferating cell nuclear antigen (PCNA) was detected using an immunohistochemical technique.

Results

The ADC values of PCa, BPH, and PZ were 49.32 ± 12.68 × 10^?5 mm²/s, 86.73 ± 26.75 × 10^?5 mm²/s, and 126.25 ± 27.21 × 10^?5 mm²/s, respectively. The ADC values of PCa were lower than those of BPH and PZ (P < 0.05). The cellularity and PCNA labeling index (LI) of PCa were higher than those of BPH (P < 0.05). The ADC values of PCa were negatively correlated with those of cellularity and PCNA LI (r = ?0.646 and ?0.446, respectively; P < 0.05).

Conclusion

The ADC values of PCa can reveal the differences in proliferative activity between PCa and BPH. These values are therefore able to predict the proliferative rate of variously differentiated prostate cancers. J. Magn. Reson. Imaging 2009;29:1360–1366. © 2009 Wiley‐Liss, Inc.

     

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.     

Characterization of chondroblastic osteosarcoma: Gadolinium‐enhanced versus diffusion‐weighted MR imaging

Purpose

To detect differences in magnetic resonance imaging (MRI) between chondroblastic osteosarcoma and the other types of osteosarcomas or chondrosarcomas using gadolinium‐enhanced versus diffusion‐weighted sequences.

Materials and Methods

Contrast‐enhanced MRI and diffusion‐weighted imaging (DWI) were performed in five chondroblastic osteosarcoma (CO) cases, 17 other types of osteosarcomas (OS), and 18 chondrosarcomas (CS). DWI was obtained with a single‐shot echo‐planar imaging (EPI) sequence using a 1.5T MR imager. The apparent diffusion coefficients (ADCs) of the minimum and maximum values were also obtained. The contrast‐enhancement pattern was evaluated and minimum‐maximum ADC value of CO was compared with other types of OS and CS.

Results

Both CO and CS showed a similar enhancement pattern; both showed septonodular and peripheral rim enhancement. The minimum ADC value of CO (1.24 ± 0.10 × 10^?3mm²/sec) was significantly higher than that of other types of OS (0.84 ± 0.15 × 10^?3mm²/sec) and was significantly lower than that of CS (1.64 ± 0.20 × 10^?3mm²/sec). In addition, the maximum ADC value of CO (2.28 ± 0.20 × 10^?3mm²/sec) was significantly higher than that of other types of OS (1.33 ± 0.26 × 10^?3mm²/sec).

Conclusion

DWI appears to be more useful for differentiating between chondroblastic osteosarcoma and chondrosarcoma or other types of osteosarcoma than Gd‐enhanced MRI. J. Magn. Reson. Imaging 2009;29:895–900. © 2009 Wiley‐Liss, Inc.

     

Prostate cancer: utility of fusion of T2-weighted and high b-value diffusion-weighted images for peripheral zone tumor detection and localization

Purpose:

To retrospectively assess the utility of fusion of T2‐weighted images (T2WI) and high b‐value diffusion‐weighted images (DWI) for prostate cancer detection and localization.

Materials and Methods:

In this IRB‐approved HIPAA‐compliant study, 42 patients with prostate cancer underwent MRI including multiplanar T2WI and axial DWI before prostatectomy. Two independent radiologists first assessed multiplanar T2WI and axial DWI_b‐1000 images and recorded whether tumor was present in each sextant. Axial T2WI was then fused with axial DWI_b‐1000 images, and the radiologists re‐evaluated each sextant for tumor. Accuracy was compared using generalized estimating equations based on a binary logistic regression model.

Results:

The accuracy, sensitivity, specificity, PPV, and NPV for tumor detection on a sextant‐basis using separate and fused image sets was 65.1%, 50.8%, 78.0%, 67.8%, and 63.6% and 71.0%, 60.8%, 80.3%, 73.7%, and 69.3%, respectively, for reader 1, and 54.0%, 42.5%, 64.4%, 52.0%, and 55.2%, and 61.1%, 56.7%, 65.2%, 59.6%, and 62.3%, respectively, for reader 2. The improvements in accuracy, sensitivity, and NPV using fused images were statistically significant for both readers, as was the improvement in PPV for reader 2 (P ranging from <0.0001 to 0.041). With either separate or fused images, there was greater sensitivity for tumors of higher grade or larger size (P ranging from <0.001 to 0.099).

Conclusion:

Fusion of T2WI and high b‐value DWI resulted in significant improvements in sensitivity and accuracy for tumor detection on a sextant‐basis, with similar specificity. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Use of conventional MR imaging and diffusion‐weighted imaging for evaluating the risk grade of gastrointestinal stromal tumors

Purpose:

To study the risk grade of gastrointestinal stromal tumors (GISTs) with conventional MR imaging and diffusion‐weighted imaging (DWI).

Materials and Methods:

The abdominal MR images with DWI of 23 patients with pathologically proven GISTs during January 2010 to May 2011 were retrospectively reviewed. The conventional MR imaging findings and apparent diffusion coefficient (ADC) values of the tumors related to the risk grade were analyzed.

Results:

In the 23 patients, there were 13 patients with high‐risk, 5 with medium‐risk, 5 with low‐risk, and 0 with very low‐risk GISTs. Most of the conventional MR findings of the tumors did not correlate with the risk grade. The only exception to this was the correlation between risk grade and the enhancement degree of the tumor after Gd‐DTPA. The ADC values were, respectively, (1.04 ± 0.13) × 10^?3 mm²·s^?1, (1.59 ± 0.06) × 10^?3 mm²·s^?1 and (1.94 ± 0.08) × 10^?3 mm²·s^?1 (P < 0.05) in the high‐, medium‐, and low‐risk grade groups. The ADC values of GISTs decreased with the increase of the risk grade of the tumors (r = ?0.957; P < 0.05).

Conclusion:

DWI can be used to assess the risk grade of GISTs, but conventional MR imaging is of limited use. J. Magn. Reson. Imaging 2012; 36:1395–1401. © 2012 Wiley Periodicals, Inc.