Imaging modalities in prostate cancer Bahjat moussa PGY4 urology Dr Georges Assaf Moderator 24-04-14

PET in PC patients Role of functional imaging The aim of this review not well established yet The aim of this review to offer an overview about the main applications of choline PET in PC patients

Detection of intra-prostatic cancer

The only potential application of PET/CT Use of choline PET/CT for initial diagnosis and local staging of prostate cancer not recommended as a first line screening method The only potential application of PET/CT increase the detection rate of cancer on repeated TRUS-guided biopsies in patients in which at least 2 inconclusive TRUS-guided biopsy have been already performed

Staging

The use of choline PET/CT for preoperative LN staging showed very contradictory results However good specificity and PPV limited to patients with very high risk for LN positive status according to nomograms

At the present time routine clinical use of choline PET/CT cannot be recommended in staging patients with PC

A negative Choline PET/CT is not sufficient to rule out a lymph-adenectomy PET could be useful to exclude from surgery patients with high surgical risk in which the presence of LN lesions were assessed by PET (high PPV)

PET/CT showed sensitivity 60% a much better specificity 97%

Restaging

Imaging should be able to find the site of recurrence distinguish between local failure and distant metastasis

significantly high detection rate Detection of LN and distant recurrence in PC patients with biochemical recurrence significantly high detection rate relationship between detection rate and Trigger PSA values a relationship between detection rate and PSA kinetics a crucial role as first diagnostic procedure in patients who demonstrate a fast growing PSA kinetics and low Trigger PSA

In case of slow growing PSA kinetics sensitivity of PET does not seems to be so high questionable if a PET/CT should be performed as first imaging procedure

In case of local relapse TRUS and/or pelvic endorectal MR remain the first procedures choline PET/CT could have only a complementary role to exclude the presence of distant metastasis, before a local RT salvage treatment

Conclusion Use of choline PET/CT for initial diagnosis and staging is not recommended as a first-line method Most important application of choline PET/CT restaging of the disease in case of biochemical relapse for the detection of LN and distant recurrence

Conclusion Choline PET/CT could play a crucial role as first diagnostic procedure in PC patients who show a fast growing PSA kinetics

The diagnostic evidence is stronger in restaging than in staging settings

Proper patient selection PSA level PSA doubling time initial tumor stage is the key to avoiding FN results up front

The use of choline PET/CT scanning May accurately provide the localisation of the site of prostate recurrence in a single step Choline PET/CT’s detection rate of recurrences rises together with the increase in PSA serum value

According to the current available data the routine use of choline PET/CT scanning cannot be commonly recommended for PSA values <1 ng/ml

Independent predictors of positive choline PET/CT PSA DT previous biochemical failure locally advanced tumour pathologic lymph node disease at initial staging

Can choline positron emission tomography/computed tomography help individualise treatment decisions?

Confirmatory data are still needed Choline PET/CT imaging has recently been proposed to allow new opportunities for individualised treatment on recurrent lesions after radical treatment for PCa

Patients with local recurrence after RP best treated by salvage RT when the PSA serum level is <0.5 ng/ml Choline PET/CT scanning is not commonly useful in this scenario low detection rate for PSA serum values <1 ng/ml

Choline PET/CT scanning, providing whole-body information on Pca spread may be useful in selecting patients to be referred to local treatment by distinguishing those patients with local recurrences from those who present with distant metastases

Salvage lymphadenectomy Choline PET/CT scanning very useful for indicating the presence of lymph nodal involvement in patients who present with a progressive PSA increase after radical treatment it provides a basis for further treatment decisions

Role of MRI

According to the guidelines PSA increase over a threshold of 0.2 ng/ml later than 6 to 12 months after radical prostatectomy suggests treatment failure with a high risk of local recurrence increase within a shorter period correlates with distant metastasis For EBRT; biochemical failure increasing PSA level after a nadir level

Transrectal ultrasound-guided biopsy The current reference standard for the detection of local recurrence in patients with biochemical failure Invasive may fail to depict some tumours because only a small fraction of the gland is sampled

Computed tomography Not widely used for the detection of local recurrence low accuracy in the differentiation of local recurrence from postsurgical scarring

MRI MRI can accurately detect local recurrences after EBRT and radical prostatectomy DCE MRI is particularly accurate The addition of 1H-MRSI to DCE MRI significantly improve the diagnostic accuracy of local prostate cancer recurrence

MRI usually used for local staging in intermediate and high risk patient groups useful in low risk patients as well sensitivity and specificity 75% and 95% respectively

Functional MRI techniques diffusion-weighted magnetic resonance (DW-MR) dynamic contrast-enhanced (DCE-MR) MR spectroscopy

Conventional MRI only able to diagnose metastatic lymph nodes bigger than 10 mm A newly invented MRI technique lymphotropic superparamagnetic nanoparticles detect occult lymph node metastasis smaller than 10 mm 100% sensitivity and 95.7% specificity

MR Spectroscopy Measures the level of specific metabolites in the prostate gland Combination of choline and creatine is measured in MRS The other metabolite that MRS measures is citrate accumulate in peripheral zone high in normal prostate tissue but decreases in malignant tissues

MR Spectroscopy The ratio of Cho+Cr/Ci Higher ratio used for evaluation of prostate cancer Higher ratio in favor of higher risk of malignancy more than 0.75 is considered as significant and is consistent with prostate cancer

MR Spectroscopy More accurate in detecting prostate cancers with high grade of malignancy in low grade cancers its accuracy is limited

Dynamic Contrast Study Works based on neo angiogenesis in tumor cells Angiogenesis rate is high newly made vessels have low integrity in their wall more permeable than normal vessels

Dynamic Contrast Study Gadolinium contrast agent is injected then serial 3D T1- weighted images are obtained Fast leakage of contrast agent from leaky tumoral vasculature early enhancement of tumoral tissue in T1 - weighted MRI early wash out of contrast agent are seen in prostate cancer

Diffusion Weighted Imaging Works based on water molecules movements Water molecules movement decrease in a high cellular environment so diffusion become lower Sensitivity and specificity of DWI when added to T2-Weighted MRI for detecting prostate cancer is about 84% and 87% respectively

MRI Ability to Detection Bony Metastasis The most sensitive and specific technique in detecting bony metastasis

Whole-body DW imaging The most newly MRI technique Very helpful in detection of prostate cancer and its metastasis as well as post cancer therapy fallow up

Local Staging of Prostate Cancer High resolution MR images especially with the use of endorectal coil can show with high accuracy whether the tumor is confined to prostate gland or there is extra capsular extension

The gold standard approach for: Diagnosis Staging and management of prostate cancer Is using 1.5 T MR machines with both endorectal and pelvic phased-array coils

Evaluation of Local Recurrence After Treatment MR spectroscopy detects recurrence after radical prostatectomy 84% and 88% sensitivity and specificity respectively DWMRI capable to detect cancer recurrence after radical prostatectomy in patients that conventional MRI has missed recurrence

In combination with T2-Weighted MRI DW-MR imaging alone shows low sensitivity in cancer recurrence detection after radiotherapy (25%) In combination with T2-Weighted MRI sensitivity increases to 62% Specificity in both condition is acceptable (92% vs 97%)

High resolution Multiparametric MR imaging includes: regular T1 weighted and T2 weighted images dynamic contrast-enhanced MRI diffusion weighted imaging MR spectroscopy

High resolution Multiparametric MR imaging Obtained in 1.5 T MR machines with simultaneous use of pelvic and endorectal coils best imaging modality in prostate cancer useful for detection and local staging of prostate cancer follow-up of patients after radical prostatectomy or radiation therapy detection of skeletal metastasis targeting biopsies in patients highly suspicious of prostate cancer but with previous negative TRUS guided biopsies

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