MR Imaging of Treated Prostate Cancer

MR Imaging of Treated Prostate Cancer

Nieprzeczytany postautor: zosia bluszcz » 06 lip 2021, 09:12

MR Imaging of Treated Prostate Cancer

Essentials

• The most important role of imaging is to localize recurrence when it is suspected, so that observation (if no recurrence is detected), salvage therapy (in the presence of local recurrence), or systemic therapy (in the presence of widespread disease) can be promptly instituted.

• The most common site of local recurrence after radical prostatectomy is the vesicourethral anastomosis;
the typical MR imaging appearance of recurrence is an enhancing soft-tissue nodule that is isointense to muscle on T1-weighted images and slightly hyperintense to muscle on T2-weighted images.

• The main effects of radiation therapy (RT) on the MR imaging appearance of the prostate are a decrease in size and diffusely decreased signal intensity on T2-weighted images due to glandular loss and fibrosis;
recurrent tumor typically appears on T2-weighted images as a nodular lesion of lower signal intensity than the adjacent treated prostate, with restricted diffusion and rapid enhancement, in the same location as the pre-RT tumor.

• The imaging features of the treated prostate and of prostate cancer recurrence after androgen-deprivation therapy may be similar to those after RT (decreased volume, decreased signal intensity on T2-weighted images, loss of zonal differentiation);
however, RT-induced changes in adjacent structures are absent;
at MR imaging and MR spectroscopic imaging, patients demonstrate diverse morphologic and metabolic responses, with the magnitude of responses depending on the type and duration of therapy.

After focal therapies, MR imaging is used to assess the extent and distribution of the expected necrosis in the target region:
On contrast-enhanced T1-weighted images, nonenhancing low-signal-intensity regions are expected at sites of treated tumors (representing necrosis), while focal areas of enhancement (representing viable tissue) are suspicious for recurrence


https://pubs.rsna.org/doi/full/10.1148/radiol.11101996
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