In vivo temperature mapping of prostate during treatment with TherMatrx TMx-2000 device: heat field and MRI determinations of necrotic lesions.
OBJECTIVE
The effectiveness of any thermotherapy device is determined by the temperatures created and how long they are applied. Understanding the heating characteristics of a thermotherapy device is vital to its correct implementation. Interstitial temperature mapping was used to determine the heat field created within the prostate by the TherMatrx TMx-2000 transurethral microwave thermotherapy (TUMT) device. Gadolinium-enhanced MRI was used to determine the extent, type, and pattern of coagulation necrosis caused by TUMT.


METHODS
Interstitial temperature mapping was performed during treatment in five patients with benign prostatic hyperplasia using 24 temperature sensors inserted through the perineum and arrayed throughout the prostate under ultrasound and X-ray guidance. Gadolinium-enhanced MRI scans were performed on all patients 1 week after treatment.


RESULTS
Interstitial temperature mapping found the heat field created to peak at the urethral surface near the central part of the catheter antenna. Temperatures decreased at consistent rates of 1 to 1.4 degrees C/mm radially and 0.1 to 0.5 degrees C/mm longitudinally from the peak area. Gadolinium-enhanced MRI showed minimal dispersed necrosis and only in the periurethral area.


CONCLUSIONS
The TMx-2000 can create temperatures >45 degrees C in areas 3 to 4 mm from the antenna. However, the heat pattern and protocol of the TMx-2000 produce necrosis-generating conditions only within a few millimeters of the urethra.
Larson
Benjamin
B
Institute of Medical Research, Scottsdale, Arizona 85260, USA.
Huidobro
Christian
C
Acevedo
Cristian
C
Busel
David
D
Mynderses
Lance
L
Collins
Joseph
J
Larson
Thayne
T
D001831:Body Temperature; D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009336:Necrosis; D011467:Prostate / Q000473:pathology*; D011470:Prostatic Hyperplasia / Q000473:pathology / Q000601:surgery*; D020728:Transurethral Resection of Prostate
D003287:Contrast Media; D019786:Gadolinium DTPA