Single-bolus technique for spiral CT of laryngopharyngeal squamous cell carcinoma: comparison of different contrast material volumes, flow rates, and start delays

A new CT dynamic maneuver "Mouth Opened with Tongue Extended" can improve the clinical TNM staging of oral cavity and oropharynx squamous cell carcinomas

OBJECTIVES

Cross sectional imaging is mandatory for oral cavity and oropharynx head and neck squamous cell carcinoma's (ooSCC) local extension and TNM staging. However a complex anatomy and frequent dental metallic artifacts make it difficult. This study assesses the clinical benefit of "Mouth Open with Tongue Extended" dynamic maneuver at CT (CTmote) as compared to the conventional CT (CTconv) and MRI.

MATERIAL

Retrospectively, 58 patients with histologically proven ooSCC (oral cavity: 34; oropharynx: 24) were included in the study. All had endoscopy with biopsies, MRI, CTconv and an CTmote acquisitions. Data were splitted in 3 datasets and 2 independent radiologists performed readings blindly. Gold standard was pTNM in 31% of cases; otherwise cTNM obtained at multidisciplinary team meeting with endoscopy and mapping biopsies were used.

RESULTS

CTmote was feasible for all patients including those already treated by surgery or radiotherapy. Exact TNM staging was obtained in 68%, 83%, 83% for CTconv, CTmote and MRI respectively. The best exam ratings at paired wise comparisons were 3%, 47%, 50% for CTconv, CTmote and MRI respectively. CTmote and MRI observer agreements, image quality and confidence ratings, were comparable and higher compared to CTconv (p < 0.001).

CONCLUSIONS

CTmote improves oral cavity and oropharynx tumour stage assessment compared to CTconv with performances close to those of MRI examination. In clinical practice, combining both CT with MOTE maneuver and MRI seems to be the optimal imaging strategy for local staging.

Modern Radiology in the Management of Head and Neck Cancer

The accurate staging of head and neck cancer is vital to direct appropriate management strategies and to deliver the best radiation therapy and surgery. Initial challenges in head and neck cancer imaging include determination of T- and N-stage, stage migration with detection of metastatic disease and identification of primary disease in the patient presenting with nodal metastases. In follow-up, imaging has an important role in assessing patients who may require salvage surgery after radiotherapy and assessing clinical change that may represent either residual/recurrent disease or radiation effects. This overview gathers recent evidence on the optimal use of currently readily available imaging modalities (ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography-computed tomography) in the context of head and neck squamous cell cancers.

Improved edge delineation using a low-flow and delayed-phase contrast-enhanced protocol for computed tomography imaging of oral cavity and oropharyngeal malignancies

AIM

To determine whether contrast-enhanced computed tomography (CT) performed with a high flow rate and short delay protocol or a lower flow rate and longer delay protocol resulted in better enhancement of the oral cavity and oropharyngeal tumour and tumour edge delineation.

MATERIALS AND METHODS

Patients with squamous cell carcinomas of the upper aerodigestive tract (UAT) who underwent contrast-enhanced CT using 100 ml contrast material with 300 mg iodine/ml were selected for this comparison study. The protocols studied used a high flow rate and short scan delay (2 ml/s and 50 s) and a lower flow rate and longer delay (1 ml/s and 100 s). Contrast enhancement by radiodensity in Hounsfield units of the tumour site, poorest and clearest tumour boundaries and contralateral lateral pterygoid muscle were measured using a region of interest tool. A t-test statistical analysis was used to compare both protocols.

RESULTS

The lower flow and longer delay protocol maximized contrast differences at both the poorest and clearest definition boundaries of the tumour (p ≤ 0.01 and p ≤ 0.05, respectively) and the pterygoid muscle (p ≤ 0.01). There was no significant difference in contrast enhancement within the central homogeneous tumour site.

CONCLUSION

A lower flow and longer delay protocol (1 ml/s and 100 s) provided better enhancement of the delineation of the tumour edge and surrounding musculature than a high flow rate and short delay protocol (2 ml/s and 50 s). Both protocols achieved similar central tumour enhancement.

Enhancement of anatomical structures and detection of metastatic cervical lymph nodes: comparison of two different contrast material doses

PURPOSE

To determine if a 20 % reduction in the contrast material dose is acceptable in the CT evaluation of patients with head and neck malignancy.

MATERIALS AND METHODS

Sixty consecutive patients (mean age 67 years) with head and neck malignancy underwent contrast-enhanced CT according to two different protocols: protocol A (80 mL of contrast material administered at an injection rate of 1.5 mL/s) and protocol B (100 mL at 1.9 mL/s). The enhancement of anatomical structures and detectability of metastatic nodes were compared between the two protocols. Pathologic analysis of the surgical resection served as the reference standard.

RESULTS

CT numbers of the anatomical structures were not significantly different between the two protocols. Mean sensitivity (64 and 77 % for protocols A and B, respectively), specificity (78 and 84 %), and accuracy (74 and 83 %) tended to be higher for protocol B than for A, but no significant difference was found.

CONCLUSION

Reducing the contrast material dose by 20 % did not significantly impair the enhancement of anatomical structures or the detection of metastatic cervical lymph nodes. Radiologists should therefore consider reducing the contrast material dose used in head and neck CT.

Dual-energy CT of head and neck cancer: average weighting of low- and high-voltage acquisitions to improve lesion delineation and image quality-initial clinical experience

OBJECTIVES

Mixing low- and high-voltage acquisitions of dual-energy CT (DECT) scan using different weighting factors leads to differences in attenuation values and image quality. The aim of this work was to evaluate whether average weighting of DECT acquisitions could improve delineation of head and neck cancer and image quality.

MATERIALS AND METHODS

Among 60 consecutive patients who underwent DECT scan of the head and neck, 35 patients had positive findings and were included in the study. Images were reconstructed as pure 80 kVp, pure Sn140 kVp, and weighted-average (WA) image datasets from low- and high-voltage acquisitions using 3 different weighting factors (0.3, 0.6, 0.8) incorporating 30%, 60%, 80% from the 80 kVp data, respectively. Lesion contrast-to-noise ratio (CNR), attenuation measurements, and objective noise were compared between different image datasets. Two independent blinded radiologists subjectively rated the overall image quality of each image dataset on a 5-point grading scale comprising lesion delineation, image sharpness, and subjective noise.

RESULTS

Mean venous and tumor enhancement and muscle attenuation increased stepwise with decreasing tube voltage from Sn140 kVp through 80 kVp. CNR increased significantly from Sn140 kVp to weighting factor 0.3 then to weighting factor 0.6 (P < 0.0001). The increase in CNR from weighting factor 0.6 to 0.8 then to 80 kVp was nonsignificant (P = 1.00). The 0.6 weighted-average image dataset received the best image quality score by the 2 readers.

CONCLUSION

Mixing the DE data from the 80 kVp and Sn140 kVp tubes using weighting factor 0.6 (60% from 80 kVp data) could improve lesion CNR and subjective overall image quality (including lesion delineation). This weighting factor was significantly superior to the 0.3 weighting factor which simulates standard 120 kVp acquisition.

Effects of Right- Versus Left-Arm Injections of Contrast Material on Computed Tomography of the Head and Neck

OBJECTIVE

To investigate the effects of the right- and left-arm injections of contrast material on image quality in computed tomography of the head and neck.

METHODS

Sixty patients were prospectively and randomly assigned into 2 groups. Eighty milliliters of contrast material (iodine concentration, 300 mg/mL) was administered into the right (n = 30) or the left (n = 30) antecubital vein at a 2-mL/s injection rate. The attenuation of the carotid artery (CA) and the internal jugular vein (IJV) was measured at 1.5-second intervals in each patient. The mean attenuation values for CA and IJV, the time to reach peak attenuation, the duration of diagnostic window (both CA and IJV enhancement were greater than 150 HU), the perivenous artifacts, and the retrograde flow of contrast material column from the subclavian or brachiocephalic vein were statistically compared between patients with right-arm injection and those with left-arm injection.

RESULTS

The mean attenuation values in CA and IJV were slightly higher in patients with right-arm injection than in those with left-arm injection, although no significant difference was reached (P = 0.06 for CA and 0.07 for IJV). The right-arm injection resulted in significantly reduced perivenous artifacts and retrograde flow of contrast material column. There were no significant differences in the time to reach the peak attenuation and in the duration of the diagnostic window between the 2 groups.

CONCLUSIONS

The right-arm injection of contrast material may provide better image quality in the computed tomography of the head and neck when compared with the left-arm injection.

Multi-detector row CT of the head and neck: comparison of different volumes of contrast material with and without a saline chaser

INTRODUCTION

The aim of this study was to determine the effect of different volumes of contrast material with and without a saline chaser on tissue enhancement in multidetector row CT (MDCT) of the head and neck.

METHODS

In a blind prospective fashion, 120 patients were randomized into the following four groups: group 1, 80 ml contrast material administered at a flow rate of 2.0 ml/s; group 2, 80 ml followed by 40 ml saline at 2.0 ml/s; group 3, 60 ml at 1.5 ml/s; and group 4, 60 ml followed by 30 ml saline at 1.5 ml/s. The attenuation values of the carotid artery, internal jugular vein, and muscle were measured at an interval of 1.5 s in each patient. The degree of perivenous artifacts was subjectively assessed.

RESULTS

Mean attenuation values in the carotid artery and internal jugular vein were significantly higher in groups 1 and 2 than in groups 3 and 4. The width of the diagnostic window (both carotid and jugular enhancement >150 HU) were significantly longer in groups 1 and 2 than in groups 3 and 4. The addition of a saline chaser did not result in improved vascular enhancement or a wider diagnostic window, but reduced perivenous artifacts, compared with using contrast material alone.

CONCLUSION

Reduction of contrast material from 80 to 60 ml results in insufficient enhancement of neck vessels. In addition, the benefit of a saline chaser technique is not obvious except for its ability to reduce perivenous artifacts.

Staging of laryngeal and hypopharyngeal cancer: value of imaging studies

Imaging methods assist in the pre-treatment planning of laryngeal and hypopharyngeal neoplasms, by better defining the local extension of infiltrating tumours and by detecting subclinical neck adenopathies. Imaging has also an important role in excluding or detecting distant metastasis. Furthermore, there is evidence that several imaging-derived parameters can be used as predictors of locoregional control after radiotherapy, and this independently from the TN classification. Such prognostic information is helpful in determining the relative value of surgery and radiation therapy, in selecting patients who may benefit from adjuvant treatment, and in identifying patients at high risk for recurrence to be followed up more closely.

Comparison of different patient positioning strategies to minimize shoulder girdle artifacts in head and neck CT

The purpose of this study was to analyze different patient positioning strategies for minimizing artifacts of the shoulder girdle in head and neck CT. Standardized CT examinations of three positioning groups were compared (P: patients pushed their shoulders downwards; D: similar optimization by a pulling device; N: no particular positioning optimization). Parameters analyzed were the length of the cervical spine not being superimposed by the shoulder girdle as well as noise in the supraclavicular space. In groups P and D, the portion of the cervical spine not superimposed was significantly larger than in group N (P: 10.4 cm; D: 10.6 cm; N: 8.5 cm). At the supraclavicular space, noise decreased significantly (P: 12.5 HU; D: 12.1 HU; N: 17.7 HU). No significant differences between the two position-optimized groups (P and D) were detected. Optimized shoulder positioning by the patient increases image quality in CT head and neck imaging. The use of a pulling device offers no additional advantages.

Computed tomography angiography versus digital subtraction angiography in vascular mapping for planning of microsurgical reconstruction of the mandible

The aim of this work was to compare the potential of computed tomography angiography (CTA) with that of digital subtraction angiography (DSA) in vascular mapping of the external carotid artery (ECA) branches for planning of microvascular reconstructions of the mandible with osteomyocutaneous flaps. In 15 patients CTA and DSA were performed prior to surgery. Selective common carotid angiograms were acquired in two projection for both sides of the neck. Sixteen-slice spiral computed tomography was performed with a dual-phase protocol, using the arterial phase images for 3D CTA reconstruction. Thin-slab maximum intensity projections and volume rendering were employed for postprocessing of CTA data. The detectability of the different ECA branches in CTA and DSA was evaluated by two examiners. No statistically significant differences between CTA and DSA (p=0.097) were found for identifying branches relevant for microsurgery. DSA was superior to CTA if more peripheral ECA branches were included (P=0.030). CTA proved to be a promising alternative to DSA in vascular mapping for planning of microvascular reconstruction of the mandible.

CT determination of lymphocytic infiltration around head and neck squamous cell carcinomas may be a predictor of lymph node metastases

The histological detection of a peritumoral lymphocytic infiltration (PLI) and a sharp tumor border in patients with squamous cell carcinoma (SCC) of the larynx, pharynx or oral cavity is inversely correlated with the development of cervical lymph node metastases and is therefore a favorable prognostic factor. However, preoperative biopsies are often too small for an evaluation of these tumor features. Here, we examined retrospectively whether elevation of peritumoral density values as determined by contrast-enhanced computed tomography (CT) correlates with PLI and the presence of cervical lymph node metastases. A total of 40 patients with primarily resected SCC were studied (pT1=8, pT2=13, pT3=9, pT4=10); 25 patients were pN-positive. All tumors were histologically analyzed regarding PLI (present or not) and the tumor border (sharp or infiltrating). Based on standardized CT examinations (90 ml contrast agent at 1.5 ml/s), repeated region-of-interest (ROI)-based peritumoral density measurements were obtained. Correlations between CT density, PLI, tumor border and metastatic involvement of regional lymph nodes were statistically evaluated. CT densities were significantly higher (P<0.001) in patients with PLI and sharp tumor borders than in patients without PLI and patients with infiltrating tumor borders. Moreover, the presence of PLI, sharp tumor borders and elevated peritumoral CT densities were each correlated with the absence of lymph node metastases (P<0.001). An elevation of peritumoral CT densities is linked to PLI and sharp tumor borders on histology and a lower risk to develop lymph node metastases. For a patient-adapted therapy, these relations have to be prospectively evaluated regarding their prognostic relevance.