Yannick Hervieux

Seed migration in prostate brachytherapy depends on experience and technique

PURPOSE To determine seed loss and pulmonary migration rate over time in permanent seed prostate brachytherapy. METHODS AND MATERIALS We analyzed the first 495 patients treated in our department. All patients were treated with loose (125)I seeds with automated seed delivery system and real-time intraoperative planning. Pelvic fluoroscopic imaging was done 30 days after the implant. Patients were divided into five groups of 100 patients according to the order they were treated, and groups were compared using χ(2) test and one-way analysis of variance. RESULTS A total of 22.8% of patients lost at least one seed. The highest percentage of patients losing any number of seeds was in the first 100. Thirty-eight percent lost at least one seed. This number decreased gradually and was only 9% in Patients 400-499. The mean total seed loss rate (number of seeds lost/number seeds implanted) changed significantly over time (p<0.001). There was a continuous significant (p<0.001) decline after the first 100 patients (1.25% for the first 100 patients) followed by a rise in Patients 300-399, followed by another decline (0.21% for the last 100 patients). The seed loss rate to the thorax changed significantly over time (p=0.009). It rose after an initial rate of 0.25-0.42% in Patients 200-299 and 300-399 and declined later to a rate of 0.21% in the last 100 patients. CONCLUSIONS We found a learning curve for seed migration. Avoiding implanting seeds outside of the capsule and modern transrectal ultrasound imaging can help decrease migration.

Urethra-Sparing, Intraoperative, Real-Time Planned, Permanent-Seed Prostate Brachytherapy: Toxicity Analysis

PURPOSE To report the toxicity outcome in patients with localized prostate cancer undergoing (125)I permanent-seed brachytherapy (BT) according to a urethra-sparing, intraoperative (IO), real-time planned conformal technique. METHODS AND MATERIALS Data were analyzed on 250 patients treated consecutively for low- or intermediate-risk prostate cancer between 2005 and 2009. The planned goal was urethral V(150) = 0. Acute and late genitourinary (GU), gastrointestinal (GI), and erectile toxicities were scored with the International Prostate Symptom Score (IPSS) questionnaire and Common Terminology Criteria for Adverse Events (version 3.0). Median follow-up time for patients with at least 2 years of follow-up (n = 130) was 34.4 months (range, 24-56.9 months). RESULTS Mean IO urethra V(150) was 0.018% ± 0.08%. Mean prostate D(90) and V(100) on day-30 computed tomography scan were 158.0 ± 27.0 Gy and 92.1% ± 7.2%, respectively. Mean IPSS peak was 9.5 ± 6.3 1 month after BT (mean difference from baseline IPSS, 5.3). No acute GI toxicity was observed in 86.8% of patients. The 3-year probability of Grade ≥2 late GU toxicity-free survival was 77.4% ± 4.0%, with Grade 3 late GU toxicity encountered in only 3 patients. Three-year Grade 1 late GI toxicity-free survival was 86.1% ± 3.2%. No patient presented Grade ≥2 late GI toxicity. Of patients with normal sexual status at baseline, 20.7% manifested Grade ≥2 erectile dysfunction after BT. On multivariate analysis, elevated baseline IPSS (p = 0.016) and high-activity sources (median 0.61 mCi) (p = 0.033) predicted increased Grade ≥2 late GU toxicity. CONCLUSIONS Urethra-sparing IO BT results in low acute and late GU toxicity compared with the literature. High seed activity and elevated IPSS at baseline increased long-term GU toxicity.

Analysis of seed loss and pulmonary seed migration in patients treated with virtual needle guidance and robotic seed delivery.

Purpose and BackgroundTo determine whether automated seed delivery system and real-time intraoperative (IO) virtual needle guidance reduce seed loss and pulmonary seed migration. Patients and MethodsWe analyzed 279 patients with low and intermediate risk prostate cancer treated in our institution with radioactive iodine (I-125) permanent seed implants. Loose seeds were exclusively used. To account for lost seeds, pelvic fluoroscopic imaging from 3 different angles was done 30 days after the implant. Posteroanterior and lateral chest x-rays were done when seed loss was confirmed. Patients were compared using the &khgr;2 test and Fisher exact test. ResultsAt least 1 seed was lost in 31.5% of patients with a migration rate of 1.02%; 9.3% of patients had at least 1 seed in the lung with a migration rate of 0.22%. The population was divided into 3 groups according to the order in which they were treated. Seed loss (P=0.02) and pulmonary seed embolization (P=0.008) were significantly lower in the second hundred than in the first hundred patients. No difference was noted between groups 1 and 3 (patient, 201–279). Peri- or extracapsular seed placement was not correlated to seed loss (P=0.780 and P=0.092, respectively). No serious complications from seed migration were reported. Seed loss did not influence dosimetry parameters (V100, V150, and D90). ConclusionOur pulmonary seed migration and total seed loss rates are comparable to the ones reported in the literature. Virtual needle guidance and automated seed delivery system are in our hand as accurate as the manual technique.

Poor Predictive Value of Intraoperative Real-Time Dosimetry for Prostate Seed Brachytherapy

PURPOSE To identify dosimetric parameters predictive of a good prostate seed I(125) quality implant. We analyzed preimplant and postimplant realtime dosimetry in patients treated with intraoperative (IO) inverse planning. METHODS AND MATERIALS We analyzed 127 consecutively treated patients with primarily low-risk prostate carcinoma who underwent prostate permanent seed I(125) brachytherapy using an IO planning approach. The implant was done using the three-dimensional transrectal ultrasound (PRE-TRUS)-guided IO interactive inverse preplanning system. The TRUS was repeated in the operating room after the implant procedure was complete (POST-TRUS). The prostate was recontoured and postimplant dosimetry was calculated. Each patient underwent computed tomography scan on Day 28 (CT-D28) to evaluate implant quality. Area under the receiver operating characteristic curves (AUROC) was evaluated for models predictive of a V100 of > or =90% and a D90 of > or =140 Gy on the basis of CT-D28 values. RESULTS On CT-D28, 72.4% of patients had a V100 of > or =90% and 74.8% had a D90 of > or =140 Gy. AUROC for a V100 of > or =90% was 0.665 (p = 0.004) on PRE-TRUS and 0.619 (p = 0.039) on POST-TRUS. AUROC for D90 of > or =140 Gy was 0.602 (p = 0.086) on PRE-TRUS and 0.614 (p = 0.054) on POST-TRUS. Using PRE-TRUS V100 cutoff of >97% gives sensitivity of 88% and a false-positive rate of 63%. A POST-TRUS D90 cutoff of >170 Gy resulted in a sensitivity of 62% and a false-positive rate of 34%. CONCLUSIONS Because of unacceptably high false-positive rates, IO preimplant and postimplant TRUS-based dosimetry are not accurate tools to predict for postimplant computed tomography-based dosimetry.

Fusion of Intraoperative Transrectal Ultrasound Images with Post-implant Computed Tomography and Magnetic Resonance Imaging

Purpose To compare the impact of the fusion of intraoperative transrectal ultrasound (TRUS) images with day 30 computed tomography (CT) and magnetic resonance imaging (MRI) on prostate volume and dosimetry. Methods and materials Seventy-five consecutive patients with CT and MRI obtained on day 30 with a Fast Spin Echo T2-weighted magnetic resonance (MR) sequence were analyzed. A rigid manual registration was performed between the intraoperative TRUS and day-30 CT based on the prostate volume. A second manual rigid registration was performed between the intraoperative TRUS and the day-30 MRI. The prostate contours were manually modified on CT and MRI. The difference in prostate volume and dosimetry between CT and MRI were compared. Results Prostate volume was on average 8% (standard deviation (SD) ± 16%) larger on intraoperative TRUS than on CT and 6% (18%) larger than on MRI. In 48% of the cases, the difference in volume on CT was > 10% compared to MRI. The difference in prostate volume between CT and MRI was inversely correlated to the difference in D90 (minimum dose that covers 90% of the prostate volume) between CT and MRI (r = -0.58, P < .001). A D90 < 90% was found in 5% (n = 4) on MRI and in 10% (n = 7) on CT (Fisher exact test one-sided P = .59), but in no patient was the D90 < 90% on both MRI and CT. Conclusions When fusing TRUS images with CT and MRI, the differences in prostate volume between those modalities remain clinically important in nearly half of the patients, and this has a direct influence on how implant quality is evaluated.