论文信息 - Contrast-enhanced conventional CT in patients after surgery for malignant tumors: evaluation of the optimal method of the administration of the contrast medium.

Contrast-enhanced conventional CT in patients after surgery for malignant tumors: evaluation of the optimal method of the administration of the contrast medium.

Patients after ablative surgery for malignant tumors require computed tomography (CT) examination of a wide area on the head and neck to follow-up for recurrence and lymph metastasis. The aim of this study was to determine a more effective method for the infusion of the contrast medium into post-operative patients undergoing conventional CT, based on the relationship between the method of administering the contrast medium and the contrast-enhancing effect in the internal jugular vein. First eleven images were selected from the existing contrast-enhanced and plain CT images in a manner such that the CT values of the internal jugular vein were distributed evenly in a range of 50-180. Seven experienced observers evaluated the contrast-enhancing effect of each image set at a window value of 40 and window widths of 120, 200, and 280. Secondly, the CT values of the right internal jugular vein were measured in a total of 10 CT images from the thyroid to maxillary sinus level from each of 60 post-operative patients. The injection needles and contrast-enhancing techniques used in the 60 patients were drip infusion using an 18G injection needle in 20, drip infusion using a 21G injection needle with bolus intravenous injection immediately before scanning in 20, and drip infusion using a 23G injection needle with bolus intravenous injection immediately before scanning in 20. A CT value of 100 or above, preferably 120 or above, in the internal jugular vein was needed for the contrast-enhancing effect of a CT image to be judged as clinically significant. Our results found that, when a conventional CT was used in patients after surgery for malignant tumors, drip infusion using a 21G or 23G injection needle should be combined with bolus injections immediately before the beginning of scanning, and at the glottis or submandibular gland level during the scanning. A sufficient contrast-enhancing effect can also be obtained by drip infusion using an 18G injection needle without bolus injection.

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