Monophasic versus biphasic contrast application in CT of patients with head and neck tumour Poster No.: C-3331 Congress: ECR 2010 Type: Topic: Authors: Keywords: DOI: Scientific Exhibit Head and Neck G. M. Weiner, S. Fischer, N. Gerova, G. Planitzer, H.-J. Raatschen; Berlin/DE computed tomography, contrast material, head and neck tumours 10.1594/ecr2010/C-3331 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 8
Purpose Head and neck tumours in contrast-enhanced CT are often obscured by high contrast artefacts generated by air-filled structures (e.g. pharynx) or dental fillings. To facilitate the detection and delineation of tumours, a strong contrast enhancement is desired. Current CT protocols recommend a single monophasic 100-130 ml bolus of contrast material (iodine concentration of at least 300mg/mL) at a flow rate of 2-2.5 ml/sec and a start delay of 50-80 sec (1, 2). Bartz et al. however stated that delayed imaging may increase enhancement of head and neck masses (3). Thus, the purpose of this study is to evaluate mono- and biphasic contrast administration protocols with regard to contrast enhancement of tumours, vessels and soft tissues in single-pass multislice CT using an equal amount of contrast agent for both protocols. Methods and Materials Two groups of 15 patients each with a head and neck tumour underwent MSCT of the head and neck (mean age 60.5±10.8 years). Contrast administration protocol Both groups received a total amount of 100 ml iopromide 300 followed by a flush of 40 ml saline solution. In the first group, a single bolus of 100 ml contrast material was administered at a flow rate of 3.0 ml/sec. Image acquisition was started with a scan delay of 50 sec. In the second group, a bolus of 60 ml contrast agent was administered at 2.5 ml/sec. After an interval of 60 sec, a second bolus of 40 ml iopromide was injected at a rate of 3.0 ml/sec, immediately followed by 40 ml saline at 3.0 ml/sec. Image acquisition was started 120 sec after initiation of the first contrast administration. Both protocols are illustrated in Figure 1 on page 3. CT protocol Images were acquired at a 16-slice-CT with following parameters: 120 kvp, tube current modulation (reference level 180 mas), slice collimation 1.5 mm, pitch 1.5. Data were reformatted at a slice thickness of 4 mm for image analysis. Data analysis Page 2 of 8
Tumour diameters and densities of tumours, common carotid arteries, internal jugular veins, submandibular glands and sternocleidomastoid muscle were measured by three independent radiologists unaware of the contrast protocol. Differences in enhancement and tumour diameters were calculated by an unpaired t-test. ANOVA was used to analyse differences among the three readers. A p-value < 0.05 was considered significant. Images for this section: Fig. 1: Protocols for monophasic (blue) and biphasic (red) administration of 100 ml iopromide 300 in MSCT of head and neck Page 3 of 8
Results Mean tumour diameters were measured as 28 ± 13 mm in the biphasic group and 29 ± 13 mm in the monophasic group (p = 0.8). The biphasic protocol yielded significantly higher mean densities in tumours (118 ± 30 HU) compared to the monophasic protocol (82 ± 17 HU, p < 0.001). An example of the tumour enhancement in both protocols is shown in Figure 1 on page 4. Differences in mean densities in submandibular glands (98 ± 35 HU vs. 79 ± 20 HU) and sternocleidomastoid muscle (69 ± 8 HU vs. 64 ± 7 HU) did not reach significance (p = 0.1 and 0.08, respectively) (Figure 2 on page 5). Both, carotid arteries (311 ± 65 HU vs. 203 ± 46 HU) and jugular veins (267 ± 87 HU vs. 199 ± 40 HU) showed significantly higher enhancement in the biphasic group, p < 0.001 and p < 0.01, respectively (Figure 3 on page 5). Differences among the three readers for density measurements of tumours, soft tissues and vasculature were not significant (Figure 4 on page 6). Images for this section: Page 4 of 8
Fig. 1: Examples of tumour enhancement and delineation (red arrow) with monophasic (a) and biphasic (b) contrast protocol. Fig. 2: Boxplots of density values in sternocleidomastoid muscle, tumour and submandibular gland after monophasic (blue) and biphasic (red) contrast administration. Page 5 of 8
Fig. 3: Boxplots of density values in common carotid artery and internal jugular vein after monophasic (blue) and biphasic (red) contrast administration. Page 6 of 8
Fig. 4: Tissue densities (mean and standard deviation) of measurements in common carotid artery (CCA), internal jugular vein (IJV), sternocleidomastoid muscle (SCM), tumour and submandibular gland as measured by three independent readers after monophasic (a) and biphasic (b) contrast administration. Page 7 of 8
Conclusion Using an equal amount of contrast agent, biphasic contrast administration has proven to be superior to monophasic administration in multislice CT of head and neck tumours with regard to tumour and vessel enhancement. Tumour detection and delineation may thus be facilitated using the biphasic contrast protocol proposed in this study. References 1. Recommendations of the Deutsche Röntgengesellschaft (AG Kopf/ Hals): http://apps.drg.de/data/die_drg/ag%20kopf-hals/ct_protokolle %20070306.pdf 2. Keberle M, Tschammler A, Berning K, Hahn D: Spiral CT of the neck: When do neck malignancies delineate best during contrast enhancement? Eur Radiol. 2001;11(10):1986-90 3. Bartz BH, Case IC, Srinivasan A, Mukherji SK: Delayed MDCT imaging results in increased enhancement in patients with head and neck neoplasms. J Comput Assist Tomogr. 2006 Nov-Dec;30(6):972-4 Personal Information Page 8 of 8