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I maging modalities in prostate cancer. Bahjat moussa PGY4 urology Dr Georges Assaf Moderator 24-04-14. PET in PC patients. Role of functional imaging not well established yet The aim of this review
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Imaging modalities in prostate cancer Bahjatmoussa PGY4 urology Dr Georges Assaf Moderator 24-04-14
PET in PC patients • Role of functional imaging • not well established yet • The aim of this review • to offer an overview about the main applications of choline PET in PC patients
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
The use of cholinePET/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 CholinePET/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%
Imaging should be able to find the site of recurrence • distinguish between local failure and distant metastasis
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 cholinePET/CT for initial diagnosis and staging • is not recommended as a first-line method • Most important application of cholinePET/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 cholinePET/CT scanning • May accurately provide the localisation of the site of prostate recurrence in a single step • CholinePET/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 • CholinePET/CT scanning is not commonly useful in this scenario • low detection rate for PSA serum values <1 ng/ml
CholinePET/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 • CholinePET/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
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 lymphotropicsuperparamagneticnanoparticles • 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 • 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
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%)