title: Contrast-enhanced conventional CT in patients after surgery for malignant tumors: evaluation of the optimal method of the administration of the contrast medium.
abstract: 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.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Wakoh
authors.forename: M
authors.initials: M
authors.lastname: Yamada
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: H
authors.initials: H
authors.lastname: Shibuya
authors.forename: N
authors.initials: N
authors.lastname: Kobayashi
authors.forename: K
authors.initials: K
authors.lastname: Kuroyanagi
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage*; D004867:Equipment Design; D005500:Follow-Up Studies; D005931:Glottis / Q000000981:diagnostic imaging; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007262:Infusions, Intravenous / Q000295:instrumentation; D007275:Injections, Intravenous / Q000295:instrumentation; D007601:Jugular Veins; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008443:Maxillary Sinus / Q000000981:diagnostic imaging; D008875:Middle Aged; D009339:Needles; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D013363:Submandibular Gland / Q000000981:diagnostic imaging; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media