A COMPARISON OF SPIRAL AND CONVENTIONAL COMPUTERIZED-TOMOGRAPHY METHODS IN DIAGNOSING VARIOUS LARYNGEAL LESIONS

Although endoscopic procedures with tissue biopsy are the mainstay in the evaluation of laryngeal lesions, radiological imaging studies rema in important, Computerized tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) are the most reliable methods, especially f or deep laryngeal compartments, cartilage, extralaryngeal structures a nd neck nodes. However, the larynx is a difficult organ for radiologic al imaging because respiration and swallowing can cause several artifa cts and distort image. In this report we studied the role of a spiral CT technique and compared this with conventional CT in 32 patients. We used the Hitachi W950SRBT machine and took both conventional and spir al sections of the larynx and neck in all 32 patients. The scans were taken with a 5-mm table motion and 5-mm section thickness in both stud ies. In the spiral technique the raw data acquired were used retrospec tively for 2-mm and 5-mm reconstructions. Anatomic details, motion art ifacts and vascular enhancements were compared by a scoring system. Th e mean values were then analyzed statistically by the paired t-test. T he average examination time was 3 min 18 s for conventional CT and 28 s for spiral CT. Anatomic detail scores were better in the 2-mm sectio n spiral CT studies compared to 5-mm section spiral and conventional C T groups. Motion artifact scores were better in the 2-mm and 5-mm spir al CT groups compared to the 5-mm conventional CT group. Vascular enha ncement scores were better in the spiral CT group. Overall, the thinne r (2-mm) sections of the spiral CT studies further improved image qual ity regarding both anatomic details and motion artifacts. Scanning tim e for spiral CT was very short, motion artifacts were less, and vascul ar enhancement and anatomic details were better. Volumetric data could also be reconstructed for thinner sections in all planes retrospectiv ely for further evaluation. Our findings showed that spiral CT was a b etter method than conventional CT for evaluating laryngeal lesions.