Diffusion-weighted magnetic resonance diagnosis of local recurrences of prostate cancer after radical prostatectomy: preliminary evaluation on twenty-seven cases.
OBJECTIVE
To assess the diagnostic performance of diffusion-weighted MR imaging (DWI) in patients affected by prostatic fossa (PF) relapse after radical prostatectomy (RP) for prostatic carcinoma (PC).


METHODS
Twenty-seven patients showing a nodular lesion in the PF at T2-weighted MR imaging after RP, with diagnosis of PC relapse established by biopsy or PSA determinations, were investigated by DWI. Two readers evaluated the DWI results in consensus and the apparent diffusion coefficient (ADC) of the nodules, separately; a mean value was obtained (ADCm).


RESULTS
Relapses did not significantly differ in size in respect of postsurgical benign nodules. The DWI qualitative evaluation showed sensitivity, specificity, accuracy, ppv, and npv values, respectively, of 83.3%, 88.9%, 85.2%, 93.7%, and 72.7% (100%, 87.5%, 95.6%, 93.7%, and 100%, for nodules >6 mm). The intraclass correlation coefficient (ICC) for ADC evaluation between the two readers was 0.852 (95% CI 0.661-0.935; P = 0.0001). The ADCm values for relapses and benign nodules were, respectively, 0.98 ± 0.21 × 10(-3) mm(2)/sec and 1.24 ± 0.32 × 10(-3) mm(2)/sec (P = 0.006). Sensitivity, specificity, accuracy, ppv and npv of ADCm were, respectively, 77.8%, 88.9%, 81.8%, 93.3%, and 66.7% (93.3%, 87.5%, 85.4%, 93.3%, and 87.5% for nodules >6 mm).


CONCLUSIONS
Diffusion-weighted MR imaging is a promising tool in the management of a hyperintense nodule detected by T2-weighted sequences. This might have a relevant importance in contouring radiotherapy treatment volumes.
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Diagnostic Imaging, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Salvatore Francesco
SF
Carbone
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Radiotherapy, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Luigi
L
Pirtoli
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Diagnostic Imaging, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Veronica
V
Ricci
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Radiotherapy, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Tommaso
T
Carfagno
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Radiotherapy, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Paolo
P
Tini
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Diagnostic Imaging, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Augusto
0000-0003-4819-1910
A
La Penna
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Diagnostic Imaging, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Eleonora
E
Cacchiarelli
Istituto Toscano Tumori, via Taddeo Alderotti 26/N, 50139 Florence, Italy ; Unit of Diagnostic Imaging, University Hospital of Siena, Policlinico S. Maria alle Scotte, Viale Bracci, 53100 Siena, Italy.
Luca
L
Volterrani
D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000601:surgery*; D011467:Prostate / Q000473:pathology / Q000601:surgery; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D012372:ROC Curve; D012015:Reference Standards