Abstract:

Objective    To evaluate the feature of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) at 3.0T for rectal diseases and to determine it′s value. Methods     DCE-MRI was performed on 51 patients with rectal diseases at 3.0T using 3D F-SPGR sequence. The contrast material was injected at the rate of 3mL/s with a dose of 0.1mmol/kg. DCE-MRI with 15-20 phases was consecutively performed once the injection of contrast media started. The timeintensity curve (TIC) was obtained and signal intensity of peak enhancement (SIpeak) and time to peak enhancement (Tpeak) of different rectal diseases and various degree of differentiation and TNM staging of rectal carcinoma were measured and compared. Results     Four types were classified for TICs according to the time to enhancement peak and washing out of the contrast material. All of adenomas presented as type A, while local recurrence of rectal carcinoma and abscesses presented as B, C or D type. The TICs of rectal carcinoma were various and changed gradually from type A to type D with the worsening of differentiation. There were significant differences among the Tpeak in different diseases. The order of the  Tpeak from early phase to late phase was adenoma, cancer, abscess and recurrence. The Tpeak became longer with the worsening of the differentiation of rectal carcinoma and depth of rectal carcinoma invasion. The Tpeak of rectal carcinoma without serosa invasion and lymph nodes metastasis was earlier than rectal carcinoma with such invasion and metastasis(P<0.05). Conclusion      TIC is helpful in the diagnosis of rectal diseases. The Tpeak is a reliable index for the diagnosis, differential diagnosis and prognosis prediction of rectal carcinoma.

Key words: Rectal tumor; Magnetic resonance imaging; Dynamic contrast enhancement