Image-Guided High-Dose-Rate (HDR) Boost Localization Using MRI/MR Spectroscopy: A Correlation Study with Biopsy

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Accurate localization of dominant intraprostatic lesions (DILs) is crucial for effective dose escalation in prostate cancer treatment.
• High-dose-rate (HDR) brachytherapy requires precise targeting of cancerous areas within the prostate gland.
• Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) offer advanced imaging capabilities for prostate cancer assessment.

Purpose of the Study:

• To evaluate the diagnostic performance of MRI sequences, including diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) mapping, and MRS, in identifying DILs.
• To compare the accuracy of these imaging techniques against prostate biopsy results for guiding dose escalation in HDR brachytherapy.

Main Methods:

• Twenty patients with intermediate-risk prostate adenocarcinoma underwent 1.5 T MRI/MRS with pelvic and endorectal coils.
• Radiologists interpreted T1W, T2W, DWI-ADC, and MRS sequences, comparing findings with transrectal ultrasonography-guided biopsy results.
• Sensitivity, specificity, and predictive values were calculated per sextant to assess diagnostic accuracy.

Main Results:

• Combined MRI/MRS/DWI-ADC mapping achieved 100% sensitivity and 49% specificity in identifying DILs compared to biopsy.
• Individual modalities showed varying performance: MRI/MRS had 98.6% sensitivity and 60.8% specificity; MRS alone had 96.4% sensitivity and 54.8% specificity; DWI-ADC mapping had 93.7% sensitivity and 82.1% specificity.
• The combined approach demonstrated high negative predictive value (100%), indicating strong reliability in ruling out DILs when negative.

Conclusions:

• The combination of MRI and MRS is a highly sensitive tool for both structural and metabolic evaluation of prostate cancer.
• MRI/MRS are effective in delineating DILs, supporting their use for planning high-dose-rate (HDR) intraprostatic boosts.
• The integrated imaging approach enhances the precision of treatment targeting in prostate cancer management.