Thermotherapy of prostate cancer using magnetic nanoparticles: feasibility, imaging, and three-dimensional temperature distribution.
OBJECTIVE
To investigate the feasibility of thermotherapy using biocompatible superparamagnetic nanoparticles in patients with locally recurrent prostate cancer and to evaluate an imaging-based approach for noninvasive calculations of the three-dimensional temperature distribution.


METHODS
Ten patients with locally recurrent prostate cancer following primary therapy with curative intent were entered into a prospective phase 1 trial. The magnetic fluid was injected transperineally into the prostates according to a preplan. Patients received six thermal therapies of 60-min duration at weekly intervals using an alternating magnetic field applicator. A method of three-dimensional thermal analysis based on computed tomography (CT) of the prostates was developed and correlated with invasive and intraluminal temperature measurements. The sensitivity of nanoparticle detection by means of CT was investigated in phantoms.


RESULTS
The median detection rate of iron oxide nanoparticles in tissue specimens using CT was 89.5% (range: 70-98%). Maximum temperatures up to 55 degrees C were achieved in the prostates. Median temperatures in 20%, 50%, and 90% of the prostates were 41.1 degrees C (range: 40.0-47.4 degrees C), 40.8 degrees C (range: 39.5-45.4 degrees C), and 40.1 degrees C (range: 38.8-43.4 degrees C), respectively. Median urethral and rectal temperatures were 40.5 degrees C (range: 38.4-43.6 degrees C) and 39.8 degrees C (range: 38.2-43.4 degrees C). The median thermal dose was 7.8 (range: 3.5-136.4) cumulative equivalent minutes at 43 degrees C in 90% of the prostates.


CONCLUSIONS
The heating technique using magnetic nanoparticles was feasible. Hyperthermic to thermoablative temperatures were achieved in the prostates at 25% of the available magnetic field strength, indicating a significant potential for higher temperatures. A noninvasive thermometry method specific for this approach could be developed, which may be used for thermal dosimetry in future studies.
Johannsen
Manfred
M
Department of Urology, Campus Mitte, Charité-Universitätsmedizin, Berlin, Germany. manfred.johannsen@charite.de
Gneveckow
Uwe
U
Thiesen
Burghard
B
Taymoorian
Kasra
K
Cho
Chie Hee
CH
Waldöfner
Norbert
N
Scholz
Regina
R
Jordan
Andreas
A
Loening
Stefan A
SA
Wust
Peter
P
D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008280:Magnetics / Q000627:therapeutic use*; D008297:Male; D053758:Nanoparticles / Q000627:therapeutic use*; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D013696:Temperature; D014057:Tomography, X-Ray Computed