Multi-centre calibration of an adaptive thresholding method for PET-based delineation of tumour volumes in radiotherapy planning of lung cancer.

PURPOSE: To evaluate the calibration of an adaptive thresholding algorithm (contrast-oriented algorithm) for FDG PET-based delineation of tumour volumes in eleven centres with respect to scanner types and image data processing by phantom measurements. METHODS: A cylindrical phantom with spheres of different diameters was filled with FDG realizing different signal-to-background ratios and scanned using 5 Siemens Biograph PET/CT scanners, 5 Philips Gemini PET/CT scanners, and one Siemens ECAT-ART PET scanner. All scans were analysed by the contrast-oriented algorithm implemented in two different software packages. For each site, the threshold SUVs of all spheres best matching the known sphere volumes were determined. Calibration parameters a and b were calculated for each combination of scanner and image-analysis software package. In addition, "scanner-type-specific" calibration curves were determined from all values obtained for each combination of scanner type and software package. Both kinds of calibration curves were used for volume delineation of the spheres. RESULTS: Only minor differences in calibration parameters were observed for scanners of the same type (Δa ≤4%, Δb ≤14%) provided that identical imaging protocols were used whereas significant differences were found comparing calibration parameters of the ART scanner with those of scanners of different type (Δa ≤60%, Δb ≤54%). After calibration, for all scanners investigated the calculated SUV thresholds for auto-contouring did not differ significantly (all p>0.58). The resulting sphere volumes deviated by less than -7% to +8% from the true values. CONCLUSION: After multi-centre calibration the use of the contrast-oriented algorithm for FDG PET-based delineation of tumour volumes in the different centres using different scanner types and specific imaging protocols is feasible.

[Endovascular brachytherapy (EVBT) with Rhenium-188 for restenosis prophylaxis after angioplasty of infrainguinal lesions: early experience]. / Endovaskuläre Brachytherapie (EVBT) mit Rhenium-188 zur Restenoseprophylaxe nach Angioplastie infrainguinaler Läsionen: Erste Erfahrungen.

PURPOSE: Restenosis remains a major problem in percutaneous transluminal angioplasty (PTA) of peripheral arteries. The aim of this feasibility study was to evaluate the technical feasibility and safety of a new endovascular brachytherapy (EVBT) device with Rhenium-188 in restenosis prophylaxis of infrainguinal arteries. MATERIALS AND METHODS: From March 2006 to April 2009, 52 patients with 71 infrainguinal arterial lesions were treated with Re-188 to prevent restenosis after PTA. 40 patients with 53 lesions (24 de-novo lesions and 29 restenoses) were reexamined (clinic, color-coded duplex ultrasound) after a mean follow-up period of 12.7 months (2.6 to 25.1 months). The liquid beta-emitter Re-188 was introduced to the target lesion via an EVBT certified PTA balloon and a tungsten applicator. After the calculated irradiation time, Re-188 was aspirated back into the tungsten applicator. A dose of 13 Gy was applied at a depth of 2 mm into the vessel wall. RESULTS: After a mean follow-up of 12.7 months, the overall restenosis rate after Re-PTA was 15.1 % (8 / 53 lesions). The restenosis rate for de-novo lesions was 20.8 % (5 / 24) and 10.3 % for restenoses (3 / 29). In 4 patients reintervention was necessary (3 PTAs and 2 major amputations). No periprocedural complications were observed. No elevated radiation dose for the patient or the interventionalist was measured. CONCLUSION: EVBT with a Re-188 filled balloon catheter was technically feasible and safe after PTA of infrainguinal arterial lesions with restenosis rates lower than expected compared to published results. Treatment of restenoses seems to be more effective than de-novo lesions.

Endovascular brachytherapy with (192)Ir and (188)Re to treat de novo and recurrent infrainguinal restenoses.

We present a review of the literature on endovascular brachytherapy (EVBT) after percutaneous transluminal angioplasty (PTA) in the femoropopliteal and tibial arteries. The pathophysiological changes induced by PTA and EVBT within the vessel wall, technical considerations regarding 192Ir and 188Re, the results of clinical trials, and the medication required before, during, and after EVBT are summarized.

[Procedure guideline for sentinel lymph node diagnosis]. / Verfahrensanweisung für die nuklearmedizinische Wächter-Lymphknoten-Diagnostik.

The authors present a procedure guideline for scintigraphic detection of sentinel lymph nodes in malignant melanoma and other skin tumours, in breast cancer, in head and neck cancer, and in prostate and penile carcinoma. Important goals of sentinel lymph node scintigraphy comprise reduction of the extent of surgery, lower postoperative morbidity and optimization of histopathological examination focussing on relevant lymph nodes. Sentinel lymph node scintigraphy itself does not diagnose tumorous lymph node involvement and is not indicated when lymph node metastases have been definitely diagnosed before sentinel lymph node scintigraphy. Procedures are compiled with the aim to reliably localise sentinel lymph nodes with a high detection rate typically in early tumour stages. Radiation exposure is low so that pregnancy is not a contraindication for sentinel lymph node scintigraphy. Even with high volumes of scintigraphic sentinel lymph node procedures surgeons, theatre staff and pathologists receive a radiation exposure <1 mSv/year so that they do not require occupational radiation surveillance.

Validation of sentinel lymph node dissection in prostate cancer: experience in more than 2,000 patients.

PURPOSE: Sentinel lymph node dissection (SLND) has replaced extended lymphadenectomy for nodal staging in several solid tumours. We present our results of SLND in prostate cancer in regard to detection and false-negative rate. METHODS: In a 2-day protocol about 300 MBq (99m)Tc-nanocolloid are injected into the prostate. Two hours later static scans of the pelvis are performed to get information about the number and location of radioactive lymph nodes. During surgery the radioactive nodes are excised with the help of a gamma probe and sent separately to the pathologist. The histological procedure includes haematoxylin and eosin staining, serial sections and immunohistochemistry. RESULTS: Since 1999, a total of 2,020 men underwent SLND alone or in combination with either standard or extended lymphadenectomy after radical retropubic prostatectomy. Lymph nodes positive for metastases were found in 16.7% of patients. The scintigraphic detection rate was 97.6% and the intraoperative detection rate 98%. For 187 lymph node-positive men who had either standard or extended lymphadenectomy in addition to SLND the false-negative rate could be calculated, resulting in false-negative findings in 11 of 187 patients (6%). CONCLUSION: Our results demonstrate that SLND in prostate cancer is a reliable procedure for nodal staging.

[Radioiodine therapy for combined disseminated and nodular thyroid autonomy. Results after using a correction term for the disseminated part]. / Radioiodtherapie bei kombinierter Schilddrüsenautonomie: Ergebnisse nach Korrektur für disseminierte Anteile.

AIM: In combined focal and disseminated thyroid autonomy a variety of concepts in the treatment with radioiodine are used. The difference lies mainly in the calculation of the autonomous volume. This retrospective study shows a new method of calculating the autonomous volume. PATIENTS AND METHODS: In 398 patients with combined thyroid autonomy and good correlation of scintigraphically hot nodules and lesions defined by ultrasound the volume of the nodules is ascertained from scintigraphic and ultrasound parameters and the volume of the disseminated autonomous tissue is assessed with a weighting factor (VF). This factor is the ratio of impulse density in a ROI over the disseminated volume divided by the corresponding impulse density over the nodular volume of the thyroid scintigraphy. The sum of nodular volume and weighted perinodular volume gives the total autonomous volume. A standard radioiodine test gives the maximum iodine-131-uptake and effective half-life to calculate the activity to obtain a treatment dose of 400 Gy. RESULTS: The rate of success with and without thyrostatic medication was 97% with an 18.6% rate of hypothyroidism observed from 4 months post therapy onwards. CONCLUSION: The use of the weighting factor VF in the treatment of combined autonomy leads to an excellent rate of success in patients with good correlation of functional imaging and ultrasound findings.

[Sentinel lymph node diagnosis in prostatic carcinoma: II. Biokinetics and dosimetry of 99mTc-Nanocolloid after intraprostatic injection]. / Sentinel-Lymphknoten-Diagnostik beim Prostatakarzinom: Teil II: Biokinetik und Dosimetrie von 99mTc-Nanokolloid nach intraprostatischer Injektion.

AIM: To visualise the sentinel lymph nodes (SLNs) of the prostate we injected the radiotracer into the parenchyma of the prostate. The activity was deposited in liver, spleen, bone marrow, urinary bladder and regional lymphatic system. The aim of this work is to determine biokinetical data and to estimate radiation doses to the patient. METHODS: The patients with prostate cancer received a sonographically controlled, transrectal administration of 99mTc-Nanocoll, injected directly into both prostate lobes. In 10 randomly selected patients radionuclide distribution and its time course was determined via regions of interest (ROIs) over prostate, urinary bladder, liver, spleen and the lymph nodes. The uptake in the SLNs was estimated from gamma probe measurements at the surgically removed nodes. To compare tumour positive with tumour free lymph nodes according to SLN-uptake and SLN-localisation we evaluated 108 lymph nodes out of 24 patients with tumour positive SLN. For calculating the effective dose according to ICRP 60 of the patients we used the MIRD-method and the Mirdose 3.1 software. RESULTS: The average uptake of separate organs was: bladder content 24%, liver 25.5%, spleen 2%, sum of SLN 0.5%. An average of 9% of the applied activity remained in the prostate. The residual activity was mainly accumulated in bone marrow and blood. Occasionally a weak activity enrichment in intestinal tract and kidneys could be recognized. The effective dose to the patient was estimated to 7.6 microSv/MBq. The radioactivity uptake of the SLN varied in several orders of magnitude between 0.006% and 0.6%. The probability of SLN-metastasis was found to be independent from tracer uptake in the lymph node. The radioactivity uptake of the SLNs in distinct lymph node regions showed no significant differences. CONCLUSION: The radiotracer is transferred out of the prostate via blood flow, by direct transfer via the urethra into the bladder and by lymphatic transport. Injecting a total activity of 200 MBq leads to a mean effective dose of 1.5 mSv. It is not recommended to use the tracer uptake in lymph nodes as the only criterion to characterize SLNs.

[Sentinel lymph node diagnosis in prostatic carcinoma: I: Method and clinical evaluation]. / [Sentinel lymph node diagnosis in prostatic caricnoma: I: Technique and clinical evaluation]

AIM: Evaluation of the significance of lymphoscintigraphy and intraoperative probe measurement for the identification of the sentinel lymph node (SLN) in prostate cancer. PATIENTS AND METHOD: In 117 patients with prostate cancer scintigrams in various projections were acquired till approximately 6 hours p.i. after ultrasound guided transrectal intraprostatic injection of 99mTc-Nanocoll. On the following day the SLNs were identified in the operation theatre with a gamma probe and removed. Pelvic standard lymph node dissection followed SLNE. RESULTS: In three of 117 patients with preoperative lymphoscintigraphy no SLN was scintigraphically detectable. These three patients had antecedent transurethral resection of the prostate. In 113 of the residual 114 patients SLN could be intraoperatively localized. In the mean four SLNs per patient were removed. 28 of 117 patients had pelvic lymph node metastases. In 25 cases SLN were right-positive, in one false-negative and in one intraoperatively not detectable. In one patient we found macrometastasis of up to 4 cm diameter (one SLN was tumour positive). In 15 cases only the SLN was bearing tumour. CONCLUSION: The SLNE with preoperative lymphoscintigraphy and intraoperative gamma probe measurement is suitable for detecting lymph node metastasis in prostate cancer. SLNE is superior to the surgical techniques commonly used in pelvic lymphadenectomy.

[Sentinel lymph node detection by preoperative lymphoscintigraphy and intraoperative gamma probe guidance in malignant melanoma]. / Nachweis des Sentinel-Lymphknotens mittels präoperativer Lymphszintigraphie und intraoperativer Gammasondenmessung bei malignem Melanom.

AIM: The purpose of this work was to prove the clinical significance of nuclear medical procedures in pre- and intraoperative detection of the SLN. METHODS: In the past 4 years, we did preoperative lymphoscintigraphy in 214 patients (pts.). Intraoperative localisation of the SLN with a hand-held gamma probe followed in 150 pts. RESULTS: In 214 pts. 247 lymphatic draining regions were found by preoperative scintigraphy. In 3 pts. with melanoma of the cheek no lymphatics/lymph nodes could be detected. 14 pts. showed interval lymph nodes. In 150 pts. gamma probe guided SLNE was done. In 2 pts. with supraclavicular primary tumor 4 SLN had been defined by preoperative scintigraphy but only 2 could be found intraoperatively. In all other cases (98.7%) the sentinel node was detected correctly by the gamma probe and then removed. In 19 of 150 pts. (12.7%) metastases were detected in the pathologic specimen. The incidence of lymph node metastases showed a continuous increase from 0% at tumor stage pT1 to 44% at stage pT4. CONCLUSION: SLNE is an accurate method to determine nodal involvement in melanoma and minimizes operative invasiveness in melanoma surgery.