J Med Assoc Thai 2016; 99 (3):338

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Original ArticleOpen Access
DCE-MRI-Derived Parameters as Predictors of Response to Neo-Adjuvant Chemoradiation Treatment of Rectal Carcinoma
Phongkitkarun S Mail, Tohmad U , Larbcharoensub N , Sumbunnanondha K , Swangsilpa T , Sirachainan E

Background: Preoperative combined chemoradiation treatment (CRT) is now accepted as the treatment of choice due to its benefits of decreasing the primary tumor volume and enhancing the sphincter preservation surgery. Determining whether a patient is responding to therapy is crucial for rectal cancer patients who may benefit from prompt treatment modifications.

Objective: To evaluate the use of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in predicting the treatment response.

Material and Method: Nineteen patients with histologically proven rectal adenocarcinoma who were candidates for neo-adjuvant CRT were prospectively included. All patients were examined by conventional and DCE-MRI at three time points (pre-, during-, and post-CRT). Surgical resection was performed after complete CRT. The pathological response and Dworak regression grade were assessed. All parameters were blindly analyzed.

Results: The median pathologic response rate for all patients was 40%. Dworak regression grades of 0, 1, 2, 3, and 4 were found in 0.0%, 21.1%, 42.1%, 26.3%, and 10.5% of patients, respectively. The tumor thickness and length were 30% and 32.9% lower at during-CRT and 40.6% and 44.7% lower post-CRT and had moderate and fair negative correlations with the pathologic response rate and Dworak regression rate, respectively. Among the DCE-MRI parameters, only a change in the time to peak between pre- and during-CRT was correlated with the Dworak regression grade (p = 0.01). The percentage change in the time to peak in patients with poor regression (grades 0-1) was significantly greater than in patients with intermediate/complete regression (grades 2-4) [139.25% vs. 6.13%].

Conclusion: Changes in the tumor thickness and length evaluated by conventional MRI and the time to peak evaluated by DCE-MRI during CRT may be useful for predicting the treatment response of rectal cancer patients.

Keywords: Rectal cancer, Magnetic resonance imaging, Contrast media, Chemoradiotherapy, Neoadjuvant therapy


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