Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

Abstract

BACKGROUND The objective of this study was to evaluate noninvasive magnetic resonance (MR) thermography for the monitoring of regional hyperthermia (RHT) in patients with soft tissue sarcomas of the lower extremities and pelvis. METHODS Noninvasive MR monitoring during RHT was performed in 9 patients who had high‐risk soft tissue sarcomas of the lower extremities or pelvis during neoadjuvant chemotherapy plus RHT in the scope of the European Organization for Research and Treatment of Cancer 62961/European Society for Hyperthermic Oncology RHT‐95 study. Anatomic and temperature‐sensitive data sets were acquired every 10 minutes before and during RHT (using gradient‐echo‐sequences with variable echo times). MR temperature distributions were derived from the phase differences by using the proton‐resonance frequency shift method. A phase convolution setting phase shifts to zero in the fat tissue was performed as a drift correction. The mean MR temperatures in the tumor and muscles and the index temperatures (e.g., T90, which covers 90% of the target volume) and thermal doses were determined and compared with pathohistologic responses and direct temperature measurements if available. RESULTS Thirty of 72 MR‐thermography data sets (>40% of heat sessions) were evaluable. A significant correlation was observed between pathohistologic response (defined as a necrosis rate ≥90%) and standardized thermal parameters, such as thermal dose cumulative equivalent minutes at 43°C to 90% of the target volume (T90) (P = .050), mean T90 (P = .048), or T50 (P = .050). The correlation of 13 conventional temperature measurements performed in selected patients and sessions invasively in the tumor or noninvasively in rectum and bladder revealed an excellent correlation with MR temperatures (R2 = .96). CONCLUSIONS Noninvasive MR thermography of soft tissue sarcoma was feasible and suitable for validating the quality of heating during RHT. Cancer 2006. © 2006 American Cancer Society.

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

“…MR guided RF hyperthermia on the other hand has been used successfully to treat human high grade sarcoma of the extremities or pelvis (105,106,135) and recurrent rectal carcinoma (49). Lengthy treatment times of >1h evoked magnetic field drifts which were corrected by using external probes, the water bolus surrounding the patient or anatomical fat references with polynomial background phase fitting (46,49,106,135).…”

“…Lengthy treatment times of >1h evoked magnetic field drifts which were corrected by using external probes, the water bolus surrounding the patient or anatomical fat references with polynomial background phase fitting (46,49,106,135). With this correction in place the standard deviation of PRF thermometry to fiber optic measurements was found to be ~1°C (Figure 1b …”

Rationale for and measurement of liposomal drug delivery with hyperthermia using non-invasive imaging techniques

“…This could be obtained using non-invasive MR thermometry 42,43 . If local temperature is not known, drug dose concentrations can still be evaluated after hyperthermia treatment with the high resolution of MRI to identify undertreated areas that can be the target of subsequent treatments.…”

Thermal Therapy as Multidisciplinary Therapy Applied to Rectal Cancer:

“…In recently, there has been significant progress in the development and application of hyperthermia treatment planning software and non-invasive thermometry [40][41][42][43][44][45] .…”