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 remain important. Computerized tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) are the most reliable methods, especially for deep laryngeal compartments, cartilage, extralaryngeal structures and neck nodes. However, the larynx is a difficult organ for radiological imaging because respiration and swallowing can cause several artifacts 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 spiral 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 studies. In the spiral technique the raw data acquired were used retrospectively for 2-mm and 5-mm reconstructions. Anatomic details, motion artifacts and vascular enhancements were compared by a scoring system. The mean values were then analyzed statistically by the paired t-test. The 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 section spiral CT studies compared to 5-mm section spiral and conventional CT groups. Motion artifact scores were better in the 2-mm and 5-mm spiral CT groups compared to the 5-mm conventional CT group. Vascular enhancement scores were better in the spiral CT group. Overall, the thinner (2-mm) sections of the spiral CT studies further improved image quality regarding both anatomic details and motion artifacts. Scanning time for spiral CT was very short, motion artifacts were less, and vascular enhancement and anatomic details were better. Volumetric data could also be reconstructed for thinner sections in all planes retrospectively for further evaluation. Our findings showed that spiral CT was a better method than conventional CT for evaluating laryngeal lesions.