PubMed Health⌕ Search

Biomedical subjects

Michael Hamm

Publications and source records attributed to Michael Hamm.

8 recordsLinked to original sources
PubMed2003

Prostate lymphoscintigraphy for sentinel lymph node identification in canines: reproducibility, uptake, and biokinetics depending on different injection strategies.

At present there are neither clinical nor experimental data available on the influence of technical details on the quality and reproducibility of prostate lymphoscintigraphy. Six adult fox hounds received repeated transrectal ultrasound guided intraprostatic injections of a technetium 99m labeled nanocolloid to prove the influence of different techniques of injection (one central injection in both prostate lobes vs two peripheral injections in both lobes) on tracer accumulation in sentinel lymph nodes (SLN) and other organs. The reproducibility of the favored technique was examined and in a last step it was subject to scrutiny following a reduction of the injected volume to 1% of the prostate volume. The number of scintigraphically visualized SLN varied between four and seven. They were located in the region of the internal and external iliac vessels, presacrally, paravesically, and directly paraprostatically. In five of six cases, the localization was reproducible both with the central application of an identical volume as well as with the volume reduced central injection. Tracer accumulation of SLNs and other organs varied enormously. We expect that with the combination of both injection techniques, even with the reduced injection volume, an optimized prostate lymphoscintigraphy will be the outcome.

Animals↗
PubMed2003

The influence of serial sections, immunohistochemistry, and extension of pelvic lymph node dissection on the lymph node status in clinically localized prostate cancer.

OBJECTIVES: Pelvic lymph node metastases indicate a poor prognosis for patients with clinically localized prostate cancer. The aim of the study was to investigate the value of extended histopathological techniques considering the extent of pelvic lymphadenectomy and preoperative risk factors. METHODS: Total of 194 patients with prostate cancer were examined. At first all patients had a sampling of the sentinel lymph nodes (SLN) followed in most cases by a modified or extended pelvic lymphadenectomy. Step sections, serial sections and immunohistochemistry (IHC, pancytokeratin antibody) were analyzed in all SLN and so-called non-SLN of the first 100 patients. Later serial sections and IHC of non-SLN were left out. RESULTS: In 26.8% lymphatic metastases were found. The detection rate of lymph node-positive patients depend significantly on the chosen extension of pelvic lymphadenectomy. Limiting the histopathological investigation to the lymph node specimen of the obturator fossa only 44.2% of lymph node-positive cases would have been identified. An additional inclusion of all lymph nodes surrounding the external iliac vessels improves the sensitivity to 65.4% (46.7% and 73.3% for the first 100 patients). Compared to the extension of pelvic lymphadenectomy the diagnostic gain of serial section and IHC (13.8% versus 53.3%) was comparably low. CONCLUSIONS: The extension of pelvic lymph node dissection is of outstanding value for the identification of node-positive patients. Limiting the number of lymph nodes to the ones with the highest probability of bearing lymphatic spread (SLN) makes the use of extensive histopathological techniques more feasible.

Humans↗
PubMed2003

Prostate lymphoscintigraphy and radio-guided surgery for sentinel lymph node identification in prostate cancer. Technique and results of the first 350 cases.

INTRODUCTION: Having in mind the promising results of lymphoscintigraphy and intraoperative gamma probe application for the detection of sentinel lymph nodes (SLN) in malignant melanoma, breast and penis cancer, we tried to identify the SLN in prostate cancer by applying a comparable technique. MATERIALS AND METHOD: 350 patients with prostate cancer were examined after providing informed consent. The day before pelvic lymphadenectomy technetium-99m nanocolloid was transrectally injected into the prostate under ultrasound guidance. A single central application was done per prostate lobe in most cases. Activity attained 90- 400 MBq, and the total injected volume was about 2-3 ml. Hereafter, lymphoscintigraphy was carried out. Those lymph nodes having been identified as SLN by means of gamma probe detection and lymphoscintigraphy were removed intraoperatively. Later, most of the cases had different types of pelvic lymphadenectomy. SLN received serial sections and immunohistochemistry, non-SLN step sections. RESULTS: 335 patients showed at least 1 SLN in lymphoscintigraphy. 24.7% had lymph node metastases. In 2 patients, metastases in non-SLN were found without at least one SLN being affected (false-negative patient). CONCLUSION: Our experience suggests that the SLN identification is not only feasible in breast cancer and malignant melanoma, but also in prostate cancer with a comparable technique.

Humans↗
PubMed2003

A new modification of the Chiron ACS assay for total prostate-specific antigen achieves equimolar response characteristics and improves the detection of prostate cancer.

Nonequimolar-response assays for prostate-specific antigen (PSA) are criticized for overestimating total PSA in some men without prostate cancer (PCA), and underestimating total PSA in some men with PCA. We recently studied three nonequimolar-response PSA assays that had undergone modifications. While two of the studied assays achieved equimolar-response characteristics with improved areas under receiver operating characteristic (ROC) curves (AUC), the modification of the Chiron ACS PSA assay (ACS PSA2, Chiron) failed to achieve this. Recently, the ACS assay underwent another modification (ACS PSA, Bayer), which we investigated. Sera from 305 men (155 without and 150 with PCA, PSA > or = 2 and < or = 30 microg/l, Tandem-E) were measured using both modifications of the ACS assay and equimolar-response reference methods (Tandem-R free and Tandem-E, Hybritech). Molar response relative to the reference method and clinical performance (comparison of AUCs) between the previous and new ACS assay modifications were studied. The new modification of the ACS assay (ACS PSA, Bayer) achieved equimolar-response characteristics but reported lower values (average 10%) than the Tandem-E assay. Compared to the previous modification (ACS PSA2, Chiron), a 3% improvement in AUC (p = 0.01) was found. Using results of the redesigned equimolar-response assay (ACS PSA, Bayer), we calculated that 6 of 155 men without PCA in this sample set could be spared unnecessary biopsy compared with the previous nonequimolar-response assay (ACS PSA2, Chiron) without missing additional PCA (90% sensitivity). These data provide additional evidence for clinical advantages of equimolar-response over nonequimolar-response PSA assay formats.

Case-Control Studies↗
PubMed2002

Combining free and total prostate specific antigen assays from different manufacturers: the pitfalls.

OBJECTIVES: We investigated the impact of interchanging free prostate specific antigen (f-PSA) concentrations from 10 different assays over a reference total PSA (t-PSA) on predicting prostate histology with free-to-total PSA ratios (f/t-PSA). METHODS: Archival sera from 80 t-PSA- and age-matched pairs of histologically confirmed prostate cancer (PCA) and benign prostatic hyperplasia (BPH) patients with t-PSA levels between 2 and 25 microg/l were investigated. Serum aliquots were analyzed for t- and f-PSA using a reference method (Access, Beckmann-Coulter Hybritech) and 10 commercially available f-PSA assays. Passing Bablok and linear regression were performed to investigate the interassay agreement between f-PSA assays. To compare diagnostic performance, ROC curves for PCA detection were calculated for the 10 f/t-PSA combinations using the reference t-PSA as denominator. Sensitivities, specificities and f/t-PSA cut-offs were calculated for varying points of the ROC curve. RESULTS: Despite good correlation of all 10 f-PSA assays with the reference method 4 showed significantly lower mean f-PSA levels. For f/t-PSA as a predictor of prostate histology, areas under the ROC curve (AUC) varied between 0.65 and 0.71 and, if compared to the reference method (AUC=0.70), were significantly lower in three cases. Ensuring 80% specificity, sensitivities ranged between 34% and 54% (reference method: 53%) and f/t-PSA cutpoints differed considerably depending on the f-PSA assay used (range: 0.15-0.24; reference: 0.15). Similar variations were noted at 95% specificity and 80% and 95% sensitivity. CONCLUSIONS: Arbitrary combinations of f- and t-PSA assays should not be used to calculate f/t-PSA ratios unless adequate studies have validated the diagnostic performance and cut-offs of that particular assay choice.

Aged↗
PubMed2002

Brachial plexus neurotization with donor phrenic nerves and its effect on pulmonary function.

OBJECT: To examine possible side effects of neurotizations in which the phrenic nerve was used, pulmonary function was analyzed pre- and postoperatively in patients with brachial plexus injury and root avulsions. METHODS: Twenty-three patients with complete brachial plexus palsy underwent neurotization of the musculocutaneous nerve, with the phrenic nerve as donor material. Patients who suffered lung contusions as part of the primary injury were excluded from this study. In 12 patients (five left-sided and seven right-sided neurotizations) pre- and postoperative functional parameters were compared and additional body plethysmography was performed more than 12 months postsurgery. Of the 23, no patient experienced pulmonary problems postoperatively. Nonetheless, pulmonary functional parameters showed a vital capacity in percent of the predicted value of 9.8 +/- 6.3% (mean +/- standard deviation [SD]) in all patients examined, which was a significant reduction (p = 0.0002). In right-sided phrenic nerve transfers this reduction was significant, at 14.3 +/- 3.3% (mean +/- SD), whereas left-sided transfers showed a nonsignificant reduction of 3.6 +/- 3.5% (mean +/- SD). The observed decrease in vital capacity (VC) correlates with the maximal inspiratory pressure (Pi(max)) as an indication of clinical significance. CONCLUSIONS: When the right phrenic nerve is used as a donor in neurotization of the musculocutaneous nerve, the patient incurs a higher risk of reduced pulmonary VC. If possible, the left phrenic nerve should be preferred. The Pi(max) has to be determined preoperatively to avoid any further decrease in the already reduced pulmonary function due to the initial injury.

Adolescent↗
PubMed2002

Low dose unenhanced helical computerized tomography for the evaluation of acute flank pain.

PURPOSE: Unenhanced helical computerized tomography (CT) has proved to be an excellent diagnostic tool for evaluating acute flank pain with reported 95% to 100% sensitivity, 92% to 100% specificity, 96% to 100% positive and 91% to 100% negative predictive values. The diagnostic value of a new low dose protocol was prospectively studied and compared with the results of conventional unenhanced helical CT in a previous series with an effective dose equivalent (HE) of 3.1 to 4.3 mSv. and in current literature with an estimated HE of 4.3 to 4.7 mSv. MATERIALS AND METHODS: In 109 patients 18 to 86 years old with acute flank pain we performed low dose unenhanced helical CT in addition to abdominal ultrasound and urinalysis with new CT parameters (120 kV. 70 mA., 5 mm. collimation, pitch 2 and incremental reconstruction each 5 mm.) that led to a more than 50% decrease in radiation exposure to 1.50 mSv. in females and 0.98 mSv. in males. Ureteral calculi were confirmed or excluded by retrograde ureteropyelography in 51 cases. In the other cases the diagnosis was verified by the clinical and ultrasound course, and/or stone asservation. RESULTS: In 80 of the 109 patients the flank pain was caused by a ureteral calculus. Low dose unenhanced helical CT precisely identified 77 ureteral calculi with 1 false-positive finding. Thus, the sensitivity and specificity of low dose unenhanced helical CT were 96% and 97% with a 99% positive and 90% negative predictive value. In 15 of 29 patients with CT findings negative for stone disease different causes of pain were established by low dose unenhanced helical CT. CONCLUSIONS: Even with the significantly decreased radiation exposure of the low dose protocol unenhanced helical CT is still an excellent and rapid diagnostic tool for evaluating acute flank pain with lower radiation exposure than excretory urography (HE 1.3 to 2.3 mSv.) at our departments. Only in obese patients with a body mass index of greater than 31 kg./m.2 is conventional unenhanced helical CT with higher radiation exposure recommended to achieve adequate image quality.

Acute Disease↗