Preliminary results on the influence of chemoradiation on apparent diffusion coefficients of primary rectal carcinoma measured by magnetic resonance imaging.
OBJECTIVE
To study changes of the apparent diffusion coefficient (ADC) measured by magnetic resonance imaging (MRI) in patients with primary rectal carcinoma during a course of combined chemoradiation.


METHODS
Diffusion-weighted echo-planar imaging at 1.5 T was performed in patients (n = 8) with primary rectal carcinoma (cT3) undergoing preoperative chemoradiation. Mean tumor ADC values and ADC histograms were determined and compared weekly during the course of therapy. Surgical resection of the tumors enabled a correlation of ADC values with the pathologic classification.


RESULTS
In four patients tumor T-downstaging (ypT0-2) was observed, and in four patients no downstaging (ypT3) was seen. In all patients, ADC values were higher before onset of chemoradiation therapy compared to the end of chemoradiation. Separating the patients into two groups, a significant increase in ADC value during week 1 of therapy, followed by a steady decrease, was found for the therapy-responder group. In the nonresponder group, no initial increase of ADC values was observed. After the 1st week of therapy, ADC values were significantly lower in the nonresponder group during the remaining duration of therapy.


CONCLUSIONS
With these preliminary results it could be shown that MR diffusion imaging is able to detect individual changes of tumor ADC values during the course of combined chemoradiation reflecting biological changes within the tumor tissue. Further studies will be necessary to prove the possible value of totally noninvasive ADC imaging on predicting therapy outcome.
Kremser
Christian
C
Department of Radiology, University of Innsbruck, Austria. christian.kremser@uibk.ac.at
Judmaier
Werner
W
Hein
Patrick
P
Griebel
Jürgen
J
Lukas
Peter
P
de Vries
Alexander
A
D000230:Adenocarcinoma / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery / Q000628:therapy*; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000627:therapeutic use; D002405:Catheterization, Central Venous; D003131:Combined Modality Therapy; D003627:Data Interpretation, Statistical; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005472:Fluorouracil / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D008962:Models, Theoretical; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery / Q000628:therapy*; D012007:Rectum / Q000473:pathology; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome
D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil