Till Örebro universitet

PURPOSE: To assess the accuracy of conventional MRI with T1- and T2-weighted sequences in detecting lymphatic nodal spread (N1) in intermediate- and high-risk prostate cancer (PCa) patients via morphological criteria alone, extended pelvic lymph node dissection (ePLND) was used as the reference standard.

METHODS: This prospective observational study included patients between 2009 and 2016 with intermediate- and high-risk PCa according to the D'Amico criteria and an estimated risk of N1 > 20% on the basis of the Briganti nomogram. All patients underwent MRI prior to ePLND. Interobserver analysis was conducted across three centers.

RESULTS: Ninety-nine men, mean age 67 (5.7 SD), 93% high-risk PCa patients and 39.4% with N1 disease, according to ePLND, were evaluated. The pooled sensitivity of MRI for detecting N1 was 24.6% (95% CI: 16.3-35.1), whereas the pooled specificity was 95% (95% CI: 85.3-98.8). Interobserver agreement was moderate (Fleiss' κ = 0.56). All readers failed to identify patients with high-volume N1, and the identification of those with a high number of N1 events was inconsistent across readers. The strengths of this study include the high number of N1 cases, with a median of 17 (6-40) harvested lymph nodes per participant. Limitations include the time interval between MRI and ePLND (median of 44 days) and the lack of standardized lymph node evaluation criteria, reflecting real-world clinical practice.

CONCLUSION: MRI using only T1W and T2W sequences has demonstrated limited effectiveness in lymph node staging for intermediate- and high-risk prostate cancer, even in high-volume metastatic disease. Additionally, interobserver analysis shows only moderate agreement.

AIM: To prospectively validate 3 T magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) for preoperative lymph node (LN) staging in a clinical setting, in intermediate- and high-risk prostate cancer (PCa) patients using laparoscopic extended LN dissection (ePLND) as the reference standard.

MATERIALS AND METHODS: Between August 2011 and May 2013, 40 newly diagnosed intermediate and high-risk PCa patients underwent preoperative LN staging with 3 T MRI DWI using histopathology of ePLND as the reference standard. The sensitivity, specificity, and accuracy of MRI DWI were calculated. A subgroup analysis of proven LN-positive patients was made to investigate differences in PSA, Gleason score, number, and size of LN metastases, estimated risk of LN involvement, and if curative treatment was indicated, between the true-positive and the false-negative groups.

RESULTS: A total of 728 LN were harvested from six anatomical regions per patient (external, obturator, internal) with a mean number of 18 LNs per patient (range 11-40). Twenty patients had histologically proven LN-positive disease. MRI DWI was true positive in 11 patients, false negative in nine patients, false positive in two patients, and true negative in 18 patients, resulting in 90% specificity, 55% sensitivity, and 72.5% accuracy. The true-positive patients had significantly more involved LNs (mean 6.9 versus 2.7, p=0.017), with larger diameter (mean 12.3 versus 5.2 mm, p=0.048) and fewer were treated with curative intent (six versus nine, p=0.03), compared with the false-negative group.

CONCLUSION: MRI DWI LN staging has a low sensitivity but high specificity. The true-positive patients have a considerably higher burden of LN metastases compared to false-negative patients.

OBJECTIVES: To evaluate the accuracy of the radiopharmaceutical [(11) C]-acetate combined with positron emission tomography/computer tomography (acetate-PET/CT) in lymph node (LN) staging in newly diagnosed prostate cancer cases. A second aim was to evaluate the potential discriminative properties of acetate-PET/CT in clinical routine.

PATIENTS AND METHODS: In a prospective comparative study, from July 2010 to June 2013, 53 men with newly histologically diagnosed intermediate- or high-risk prostate cancer underwent acetate-PET/CT investigation at one regional centre before laparoscopic extended pelvic LN dissection (ePLND) at one referral centre. The sensitivity, specificity and accuracy of acetate-PET/CT were calculated. Comparisons were made between true-positive and false-negative PET/CT cases to identify differences in the clinical parameters: PSA level, Gleason status, lymph metastasis burden and size, calculated risk of LN involvement, and curative treatment decisions.

RESULTS: In all, 26 patients had surgically/histologically confirmed LN metastasis (LN+). Acetate-PET/CT was true positive in 10 patients, false positive in one, false negative in 16, and true negative in 26. The individual sensitivity was 38%, specificity 96%, and accuracy 68%. The acetate-PET/CT positive cases had significantly more involved LNs (mean 7.9 vs 2.4, P < 0.001) with larger cancer diameters (14.1 vs 4.9 mm, P = 0.001) and fewer eventually had treatment with curative intent (40% vs 94%, P <0.005), although we lack long-term outcome data.

CONCLUSION: Acetate-PET/CT has too low a sensitivity for routine LN staging but the specificity is high. The acetate-PET/CT positive cases have a very high burden of LN spread.