[Perfusion-index values evaluated by dynamic magnetic resonance imaging in advanced rectal carcinoma. A new predictor of response to  preoperative radiochemotherapy?].
OBJECTIVE
The aim of our study was to evaluate in vivo the influence of tumor microcirculation data on therapy outcome.


METHODS
Tumor perfusion data of primary rectal carcinoma (n = 14, cT3) who underwent preoperative chemoradiation have been analyzed (Table 1). The perfusion data were acquired at the beginning and at the end of therapy by use of an ultrafast T1-mapping sequence on a whole-body magnetic resonance imager. The gadolinium-DTPA concentration-time-curves were evaluated for arterial blood and tumor before, during and after intravenous constant rate infusion and from that the perfusion index (PI) was calculated. Subsequent resection of the tumors allowed for a correlation of perfusion index values with the pathological classification.


RESULTS
Nine patients showed a T downstaging (ypT0-2, group 1), 5 patients did not (ypT3, group 2). The initial mean perfusion index value of group 1 (n = 9) was 8.2 ml/min/100 g (+/- 2) and for group 2 (n = 5) 10.4 ml/min/100 g (+/- 0.4). The difference in perfusion index values before chemoradiation between group 1 and group 2 was significant different (p = 0.012, Mann-Whitney test). The perfusion index value at the end of therapy of group 1 (n = 6) was 9.6 ml/min/100 g (+/- 2.8) and for group 2 (n = 4) 10.7 ml/min/100 g (+/- 1.6). The difference in perfusion index values after chemoradiation between group 1 and group 2 was not significant different (Table 2).


CONCLUSIONS
Our used perfusion index value combines 2 parameters: tumor perfusion and extraction fraction. Therefore a significant negative influence on therapy outcome of high perfusion index values could be explained possibly by areas with a high portion of high perfusion (e.g. av-shunts) and a low extraction fraction (= low exchange of nutrients). However, we could show a significant negative influence of high perfusion index values on therapy outcome (p = 0.012). Because the tumor stage has a significant influence on tumor-free survival, there is a possibility for using initial perfusion index values as a new prognostic factor in rectal carcinoma without sphincter infiltration undergoing a preoperative chemoradiation. To examine this hypotheses a prospective trial is in preparation.
DeVries
A
A
Universitätsklinik für Strahlentherapie, Leopold-Franzens-Universität Innsbruck, Osterreich. Alexander.deVries@uibk.ac.at
Griebel
J
J
Judmaier
W
W
Kremser
C
C
Rieger
M
M
Gneiting
T
T
Lukas
P
P
D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009367:Neoplasm Staging; D004369:Pentetic Acid / Q000493:pharmacokinetics; D012004:Rectal Neoplasms / Q000098:blood supply / Q000175:diagnosis* / Q000188:drug therapy / Q000532:radiotherapy / Q000601:surgery; D012039:Regional Blood Flow
D004369:Pentetic Acid; D019786:Gadolinium DTPA