Improved prostate cancer imaging with SPECT/CT and MRI/MRSI

Abstract

We propose a combined imaging technique for prostate cancer using /sup 111/In-ProstaScint SPECT/CT and MRI/MRSI. When used alone, either SPECT/CT or MRI/MRSI has limitations in assessing the patient undergoing clinical prostate cancer management. However, combined imaging can use MRI/MRSI to assess the prostate gland while SPECT/CT /sup 111/In-ProstaScint imaging can evaluate nearby and distant lymph nodes for metastases. The combined imaging study thereby provides complementary information useful for the cancer management. /sup 111/In-ProstaScint SPECT data are reconstructed using an iterative algorithm that includes CT-derived attenuation correction and depth-dependent collimator blurring compensation. 3D MR spectra are overlaid on the T2-weighted MR image. Image data from 3 patient studies demonstrate the potential role of combined /sup 111/In-ProstaScint SPECT/CT and MRI/MRSI imaging of prostate cancer. In the first, SPECT/CT revealed increased uptake of /sup 111/In-ProstaScint, but that occurred beyond the sensitive region of MRSI. Images from a second patient sequentially received /sup 111/In-ProstaScint SPECT/CT and MRI/MRSI in one and half months and were correlative and complementary to each other. Images from a third patient who had undergone androgen deprivation therapy show that MRI improved anatomical definition in comparison to CT, with /sup 111/In-ProstaScint indicating disease where MRSI was either equivocal or indicated atrophy. Overall, MRI/MRSI generally provided better specificity for the cancer detection within the prostate in the absence of androgen deprivation therapy, and better anatomic details of the prostate than /sup 111/In-ProstaScint SPECT/CT. Yet, /sup 111/In-ProstaScint SPECT/CT improves sensitivity for detection of distant lymph node metastases, and also is more sensitive when the patient is undergoing androgen deprivation therapy and thereby provides useful diagnostic information that complements the MRI/MRSI study alone.