Role of dynamic MRI in the evaluation of head and neck cancers treated with radiation therapy

Dynamic MR Imaging and Radiotherapy

“…1,3,4,8 Coronal images are useful, especially in lingual carcinomas and in the evaluation of tumor extent to the skull base, while sagittal images are useful in uterine tumors. In some cases, axial or coronal short-tau-inversion-recovery (STIR) sequence images are also useful.…”

“…Under these conditions, T1-weighted imaging methods such as fast spin-echo or gradient-echo techniques are usually applied. [1][2][3][4]8 Immediately after bolus injection of 0.1 mmol W kg of Gd-DTPA (Magnevist, Schering, Germany) or Gd-DOTA (Prohance, BrystolMyers, UK) and ‰ushing with 5 ml to 10 ml of normal saline, rapid T1-weighted imaging sequence is repeated every 15 to 30 seconds up to 3 to 10 minutes after injection. In our institution,ˆve sections of 4 mm slice thickness dynamic MR images using the spin-echo technique (TRࢼ200-230 msec, TEࢼ12- …”

“…However, these MRIˆndings for various disorders overlap considerably and MR is unable to establish tumor characterization. [1][2][3][4][5][6][7][8] A biopsy is still required to obtain histological diagnosis.…”

“…[1][2][3][4][5][6][7] The contrast between a tumor and normal tissue is maximized in the early dynamic phase. Usually, malignant lesions show early enhancement within 90 seconds, and are washed out earlier than normal tissue.…”

“…Because of the superior contrast between tumor and normal tissue, dynamic MRI is most useful in the detection of small lesions such as residual tumors after radiation therapy and small recurrent tumors. 3 Benign lesions orˆbrotic tissues surrounding malignant lesions show gradual enhancement in dynamic MRI, which can be diŠeren-tiated from malignant tumors.…”