Biomedical subjects

F R Schuler

Publications and source records attributed to F R Schuler.

4 recordsLinked to original sources

PubMed1999

Timing of sentinel lymph node mapping after lymphoscintigraphy.

BACKGROUND: Sentinel lymph node (SLN) mapping is an effective technique for staging patients with melanoma. In an attempt to avoid reinjection of radiolabeled colloid and facilitate SLN mapping at the time of surgery, we examined whether residual radioactivity from preoperative lymphoscintigraphy could be used to accurately identify SLNs during surgery 18 to 24 hours later. METHODS: Forty-six patients with newly diagnosed melanoma underwent injection of 0.22-micron filtered technetium 99m-labeled sulfur colloid followed by lymphoscintigraphy. Patients returned the next day for SLN biopsy with Isosulfan blue dye and the hand-held gamma-probe to identify SLNs. Thirty of 46 patients underwent repeat imaging before operation. No patient had reinjection of radiocolloid. RESULTS: Ninety-five SLNs were identified on initial lymphoscintigraphy, and repeat imaging on the day of surgery confirmed all SLNs previously identified. A total of 122 SLNs (2.65 per patient) were resected from 58 basins. Eighty-four (69%) of 122 SLNs stained blue, and 118 (97%) of 122 SLNs had in vivo gamma-counts greater than 4 times background. Microscopic metastases were present in 13 (10.7%) of 122 SLNs in 12 (26.1%) of 46 patients. There have been no recurrences over a mean follow-up time of 320 days. CONCLUSIONS: Intraoperative gamma-probe detection combined with blue dye injection is highly effective in identifying SLNs 18 to 24 hours after injection of 0.22-micron filtered 99mTc-sulfur colloid. Reinjection of radiocolloid is not required. This technique avoids radiopharmaceutical administration in the operating room, minimizes radiation exposure, and increases scheduling flexibility.

Adult↗

PubMed1983

Artifacts in iodine-131 renal images due to coincidence summing of technetium-99m photons.

Technetium-99m gamma camera images of kidneys produced with an iodine-131 energy window showed "ghosts" over and between the kidneys and between the kidneys and the bladder. The cause was coincidence summing at 281 keV due to a high 99mTc counting rate. In older model cameras careful peaking with a proper energy window reduces this effect; more recently developed cameras with pileup rejection circuits do not have this problem.

Humans↗

PubMed1983

Pulmonary function in mechanically-ventilated patients during 24-hour use of a hygroscopic condensor humidifier.

Hygroscopic condensor humidifiers (HCH) are reportedly capable of humidifying even the driest of ventilator source gases with at least 30 mg H2O/liter of ventilation. To assess the adequacy of the HCH during mechanical ventilation, we studied 26 patients over a 72-hour period (alternating 24-hour periods of humidification by a conventional cascade and the HCH). In these patients, we found no significant difference in static lung compliance, airway resistance, PaO2, and PaCO2 on either system. Additionally, estimates of sputum volume (over a four-hour collection period) and clearance of aerosolized 99mTc labelled DTPA (in five of these patients) also showed no significant differences between the two systems. We conclude that the HCH is capable of supplying necessary heat and moisture to most mechanically-ventilated patients for at least a period of 24 hours.

Adult↗

PubMedDate not supplied

Validation of delayed sentinel lymph node mapping for melanoma.

PURPOSE: Sentinel lymph node mapping using radiolabeled tracer and blue dye is widely accepted and applied for staging melanoma. Common practice involves injection of radiolabeled tracer on the morning of surgery. However, optimal timing of radiolabeled colloid injection with respect to surgery remains debated. Injection on the day before surgery would offer the advantages of increased scheduling flexibility and decreased radiation exposure to the patient and operating room staff. We hypothesized that a single injection of radiolabeled colloid given 24 hours before surgery would be sufficient and would possibly improve intraoperative sentinel lymph node identification. PATIENTS AND METHODS: Ninety-five patients with newly diagnosed cutaneous melanoma underwent injection of radiolabeled colloid and lymphoscintigraphy 18 to 24 hours before surgery for sentinel lymph node mapping and biopsy. Sixty-three patients underwent repeat imaging immediately before surgery, and the images were compared with those obtained the previous day. Intraoperative mapping utilized a hand-held gamma probe and injection of blue dye to identify sentinel lymph nodes. RESULTS: Two hundred fifty-one sentinel lymph nodes were identified by initial lymphoscintigraphy in 95 patients. Delayed imagingwithout reinjection of radiolabeled tracer compared with the initial lymphoscintigraphy demonstrated no change (71%), clarification of initial ambiguous patterns (10%), or newly identified nodes (19%). Two hundred sixty-one sentinel lymph nodes were resected, of which 79% stained blue. Microscopic metastases were present in 20 sentinel lymph nodes (8%) in 19 patients (20%). All positive nodes contained radioactivity and blue dye. CONCLUSIONS: A single injection of radiocolloid 24 hours before surgery combined with intraoperative blue dye injection identified all sentinel lymph nodes and did not miss any metastatic disease. In addition, delayed imaging may clarify initial ambiguous findings and identify additional nodes at risk for metastasis. This technique produces sentinel lymph node identification rates, harvest rates, and rates of positivity comparable to those reported with the use of injection of radiolabeled tracer on the day of surgery and greatly facilitates the technical and administrative aspects of sentinel lymph node mapping.

Adolescent↗