Magnus Bolmsjö

INTRAPROSTATIC TEMPERATURE MONITORING DURING TRANSURETHRAL MICROWAVE THERMOTHERAPY FOR THE TREATMENT OF BENIGN PROSTATIC HYPERPLASIA

PURPOSE We evaluated whether the results of transurethral microwave thermotherapy improve using high intraprostatic temperatures of 55C or greater. MATERIALS AND METHODS We accrued 30 men 58 to 85 years old (mean age 69) from the waiting list for transurethral prostatic resection in whom maximum urinary flow was less than 13 ml. per second and Madsen score was greater than 8. According to the Abrams-Griffith nomogram all but 1 patient had obstruction. Before treatment 3 thin temperature probes, each containing 5 sensors in a row, were introduced into the prostate from the perineum and positioned using transurethral ultrasound guidance. The microwave power of the transurethral microwave thermotherapy equipment was set based on the actual temperature in the prostatic tissue. A temperature of at least 55C and often more than 60C was reached at the hottest spot. Treatment duration was 1 hour. Postoperatively an indwelling catheter remained in place for 2 weeks. Patients were followed for 6 months with the first followup after 3 months. RESULTS At the 3-month followup mean maximum urinary flow had increased from 7.4 to 12.5 ml. per second and the mean Madsen score had decreased from 12.6 to 2.9. At the 6-month followup mean maximum urinary flow was 12.2 ml. per second and the mean Madsen score was 3.4. Using pressure-flow data we divided the patients into responders and nonresponders. In the 18 responders maximum urinary flow had increased from 7.2 to 14.6 ml. per second (103%), the Madsen score had decreased from 12.5 to 1.4 (89%) and detrusor pressure had decreased from 9.2 to 6 kPa. (35%). CONCLUSIONS High energy transurethral microwave thermotherapy relieved bladder outlet obstruction in 60% of the patients and had a good effect on symptoms. Compared with a previous multicenter study with 40% responders, using the same criteria there were 60% responders in our series. Our results indicate that better control of intraprostatic temperature provides better results, approaching those after transurethral prostatic resection.

Blockage of the hepatic-artery blood flow by biodegradable microspheres (Spherex®) combined with local hyperthermia in the treatment of experimental liver tumors in rats

SummaryThe effect of local hyperthermia and a simultaenous blockage of the hepatic-artery blood flow by degradable starch microspheres (Spherex®) was studied in a model of liver cancer in Wistar rats. Six days after each rat was inoculated with a cell suspension (NGW) in the central liver lobe, the rats were randomly allocated into four groups. The first group served as control, the second was treated with hyperthermia, the third by degradable starch microspheres (DSM) intraarterially, and the fourth with a combination of hyperthermia and DSM intraarterially. Tumor volumes were measured at laparotomy on days 0, 7, and 14. Temperature fluctuations in the tumor correlated well with those in the liver tissue, but were 2°–4° higher. The infusion of DSM did not change the pattern significantly. The tumor volumes were homogenous between the groups at the start of treatment. The tumor growth was significantly reduced compared with the control group at day 7 in group III (P<0.05) and group IV (P<0.01) but only in group IV at day 14 (P<0.05). No differences in survival were found. Local hyperthermia concurrent with a blockage of the nutritional tumor blood flow seems to offer a more prominent and lasting tumor-growth inhibition.

Local hyperthermia in treatment of experimental liver tumors.

An experimental model for local microwave hyperthermia treatment of liver tumors is presented. Fiftyfour Wistar rats were inoculated with a transplantable adenocarcinoma (NGW) in the central liver lobe. Ten to 16 days later 28 of the rats were exposed to local hyperthermia. A master thermistor placed in the liver parenchyma adjacent to the tumor controlled the hyperthermia, and the tumor‐bearing liver lobe was maintained at 42.0°C for 1 hour. At laparotomy 7 days after treatment, the tumor volume was measured. Four weeks after tumor inoculation, autopsy was performed. The tumor and the surrounding parenchyma was excised for histopathologic examination. A statistically significant reduction in tumor growth was found after exposure to local hyperthermia, the effect of hyperthermia being most pronounced in moderate‐sized tumors (300–500 mm3 or 0.5–0.75 g). In larger tumors (>900 mm3 or >1.1 g) extensive necrosis developed after hyperthermia treatment. This indicates good tumoricidial effect even in large tumors, although this is not obvious if reduction in tumor growth is used as the only parameter to evaluate the effect of hyperthermia.

Experimental set-up for studies of microwave-induced hyperthermia in rats

A low-cost microprocessor-based temperature controller for hyperthermia experiments on rats is described. The system directs a microwave generator, used for heating, by feedback power regulating signals in accordance with the temperature in the animal. The microwave power is pulsed for short on-and-off periods and the temperature recordings are carried out during the off periods. More than 300 hyperthermia runs have been carried out on rats using this fully automated unit. The controller can direct the hyperthermia to the predetermined level with a deviation of +/- 0.1 degree C for systemic hyperthermia. For local hyperthermia in the liver, individual recorded mean temperatures were up to -0.5 degree C from the preset temperature.

A new instrument for survey monitoring of airborne xenon-133

Methods are reviewed for measuring xenon-133 contamination of the air in medical clinics. The principles of a new, simple, and low cost monitor are outlined. Results from experimental tests in laboratories and medical clinics were encouraging, indicating that the monitor is a valuable tool for survey measurements of 133Xe contamination in nuclear medicine departments.