Monitoring radiotherapy induced tissue changes in localized prostate cancer by multi-parametric magnetic resonance imaging (MP-MRI).

PURPOSE: To evaluate the utility of multi-parametric magnetic resonance imaging (MP-MRI), including dynamic contrast-enhanced MRI and diffusion-weighted MRI, for monitoring tumor tissue changes after volumetric-modulated arc radiotherapy in localized prostate cancer (PCa), and to compare the radiotherapy induced tumor tissue changes between conventional, moderate and extreme hypofractionated groups. Furthermore, we aimed to evaluate if follow-up by MRI has an incremental value compared to the standard care by prostate-specific antigen (PSA) serum level measurement. MATERIALS AND METHODS: Fifty-five men (mean age: 70±5 [SD] years; range: 60-79 years) with biopsy-proven PCa underwent MRI examination before radiotherapy, and at 3 and 12 months after radiotherapy. Pharmacokinetic analysis post-processing platform with dedicated software (Tissue 4D) was used to generate colorized parametric maps of enhancing tumors. The volume transfer constant (Ktrans), reflux constant (Kep), and initial area under curve (iAUC) were calculated from the tumors. Tumor apparent diffusion coefficient (ADC) value was measured on the ADC map. The patients were allocated into three radiotherapy groups: 17 conventional (39×2Gy), 16 moderate (20×3Gy) and 22 extreme hypofractionated (5×7.25Gy) regimen. RESULTS: Sixty lesions were detected in the prostates of the 55 patients. Follow-up MRI showed decreases in tumor size and degree of enhancement. Ktrans, Kep, and iAUC all decreased at 3 months (P<0.001, respectively) and decreased further at 12 months (P<0.001, respectively). ADC increased at 3 months (P<0.001) and increased further at 12 months (P<0.001). There were no significant differences in the percentage changes of the measured MP-MRI parameters of the tumors from baseline to 12 months between the conventional, moderate and extreme hypofractionated regimen groups. CONCLUSION: MP-MRI is a reliable tool for lesion detection and follow-up, providing both qualitative and quantitative data.

Correlation between apparent diffusion coefficient value on diffusion-weighted MR imaging and Gleason score in prostate cancer.

OBJECTIVES: To investigate whether diffusion-weighted imaging (DWI) apparent diffusion coefficient (ADC) correlates with prostate cancer aggressiveness and further to compare the diagnostic performance of ADC and normalized ADC (nADC: normalized to non-tumor tissue). PATIENTS AND METHODS: Thirty pre-treatment patients (mean age, 69years; range: 59-78years) with prostate cancer underwent magnetic resonance imaging (MRI) examination, including DWI with three b values: 50, 400, and 800s/mm2. Both ADC and nADC were correlated with the Gleason score obtained through transrectal ultrasound-guided biopsy. RESULTS: The tumor minimum ADC (ADCmin: the lowest ADC value within tumor) had an inverse correlation with the Gleason score (r=-0.43, P<0.05), and it was lower in patients with Gleason score 3+4 than in those with Gleason score 3+3 (0.54±0.11×103mm2/s vs. 0.64±0.12×10-3mm2/s, P<0.05). Both the nADCmin and nADCmean correlated with the Gleason score (r=-0.52 and r=-0.55, P<0.01; respectively), and they were lower in patients with Gleason score 3+4 than those with Gleason score 3+3 (P<0.01; respectively). Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve was 0.765, 0.818, or 0.833 for the ADCmin, nADCmin, or nADCmean; respectively, in differentiating between Gleason score 3+4 and 3+3 tumors. CONCLUSION: Tumor ADCmin, nADCmin, and nADCmean are useful markers to predict the aggressiveness of prostate cancer.

Chest CT screening of asbestos-exposed workers: lung lesions and incidental findings.

The objective of the present study is to determine the feasibility of chest computed tomography (CT) in screening for lung cancer among asbestos-exposed workers. In total, 633 workers were included in the present study and were examined with chest radiography and high-resolution CT (HRCT). A total of 180 current and ex-smokers (cessation within the previous 10 yrs) were also screened with spiral CT. Noncalcified lung nodules were considered positive findings. The incidental CT findings not related to asbestos exposure were registered and further examined when needed. Noncalcified lung nodules were detected in 86 workers. Five histologically confirmed lung cancers were found. Only one of the five cancers was also detected by plain chest radiography and three were from the group of patients with a pre-estimated lower cancer probability. Two lung cancers were stage Ia and were radically operated. In total, 277 individuals presented 343 incidental findings of which 46 required further examination. Four of these were regarded as clinically important. In conclusion, computed tomography and high-resolution computed tomography proved to be superior to plain radiography in detecting lung cancer in asbestos-exposed workers with many confounding chest findings. The numerous incidental findings are a major concern for future screenings, which should be considered for asbestos-exposed ex-smokers and current smokers.