Tumor volume: an independent predictor of outcome for laryngeal cancer

Emerging Concepts and Novel Strategies in Radiation Therapy for Laryngeal Cancer Management

Laryngeal squamous cell carcinoma is the second most common head and neck cancer. Its pathogenesis is strongly associated with smoking. The management of this disease is challenging and mandates multidisciplinary care. Currently, accepted treatment modalities include surgery, radiation therapy, and chemotherapy—all focused on improving survival while preserving organ function. Despite changes in smoking patterns resulting in a declining incidence of laryngeal cancer, the overall outcomes for this disease have not improved in the recent past, likely due to changes in treatment patterns and treatment-related toxicities. Here, we review emerging concepts and novel strategies in the use of radiation therapy in the management of laryngeal squamous cell carcinoma that could improve the relationship between tumor control and normal tissue damage (therapeutic ratio).

Three-dimensional imaging assessment of anatomic invasion and volumetric considerations for chemo/radiotherapy-based laryngeal preservation in T3 larynx cancer

OBJECTIVES

To investigate the impact of 3-Diminsional (3D) tumor volume (TV) and extent of involvement of primary tumor on treatment outcomes in a large uniform cohort of T3 laryngeal carcinoma patients treated with nonsurgical laryngeal preservation strategies.

MATERIALS AND METHODS

The pretreatment contrast-enhanced computed tomography images of 90 patients with T3 laryngeal carcinoma were reviewed. Primary gross tumor volume (GTVp) was delineated to calculate the 3D TV and define the extent of invasion. Cartilage and soft tissue involvement was coded. The extent of invasion was dichotomized into non/limited invasion versus multiple invasion extension (MIE), and was subsequently correlated with survival outcomes.

RESULTS

The median TV was 6.6 cm3. Sixty-five patients had non/limited invasion, and 25 had MIE. Median follow-up for surviving patients was 52 months. The 5-year local control and overall survival rates for the whole cohort were 88% and 68%, respectively. There was no correlation between TV and survival outcomes. However, patients with non/limited invasion had better 5-year local control (LC) than those with MIE (95% vs 72%, p = .009) but did not have a significantly higher rate of overall survival (OS) (74% vs 67%, p = .327). In multivariate correlates of LC, MIE maintained statistical significance whereas baseline airway status showed a statistically significance trend with poor LC (p = .0087 and 0.06, respectively). Baseline good performance status was an independent predictor of improved OS (p = .03) in multivariate analysis.

CONCLUSION

The extent of primary tumor invasion is an independent prognostic factor of LC of the disease after definitive radiotherapy in T3 larynx cancer.

Quantitative pretreatment CT volumetry: Association with oncologic outcomes in patients with T4a squamous carcinoma of the larynx

BACKGROUND

The purpose of this study was to determine the impact of CT-determined pretreatment primary tumor volume on survival and disease control in T4a laryngeal squamous cell carcinoma (SCC).

METHODS

We retrospectively reviewed 124 patients with T4a laryngeal cancer from 2000-2011. Tumor volume measurements were collected and correlated with outcomes.

RESULTS

Five-year overall survival (OS) for patients with tumor volume ≥21 cm³ treated with larynx preservation (n = 26 of 41) was significantly inferior compared to <21 cm³ (42% vs 64%, respectively; P = .003). Five-year OS for patients with tumor volumes ≥21 cm³ in the cohort treated with total laryngectomy followed by radiotherapy (RT; n = 42 of 83) was not statistically significant when compared to <21 cm³ (50% vs 63%, respectively; P = .058). On multivariate analysis, tumor volume ≥21 cm³ was a significant independent correlate of worse disease-specific survival (DSS; P = .004), event-free survival (P = .005), recurrence-free survival (RFS; P = .04), noncancer cause-specific survival (P = .02), and OS (P = .0002).

CONCLUSION

Pretreatment CT-based tumor volume is an independent prognostic factor of outcomes in T4a laryngeal cancer.

Reliability of Interpretation of CT Examination of the Larynx in Patients with Glottic Laryngeal Carcinoma

INTRODUCTION: Reports in literature suggest that tumor volume, cartilage invasion, and cartilage sclerosis are independent prognostic factors for tumor control in radiotherapy as primary treatment of laryngeal carcinomas.

OBJECTIVE: Assessment of the interobserver variability and prognostic value in the measurement of tumor volume, cartilage invasion, and sclerosis.

MATERIALS AND METHODS: Retrospective analysis of 55 CT scans by three independent observers. Volume measurements and determination of cartilage invasion, cartilage sclerosis, and tumor localization were calculated. Correlation between the prognostic factors and radiotherapy was calculated for each observer.

RESULTS: Values for interobserver agreement varied substantially; cartilage invasion (κ value: −0.02 to 0.66), cartilage sclerosis (κ value: 0.13 to 0.57), tumor localization of subsites (κ value: 0.03 to 0.60), and tumor volume (correlation: 0.34 to 0.73). The found interobserver variation makes it impossible to establish accurate prognostic factors.

CONCLUSION: Determination of tumor volume, cartilage invasion, and cartilage sclerosis on the basis of CT imaging shows considerable interobserver variation; clinical significance appears to be limited.

EBM rating: B-3a

Clinical outcomes in patients with T4 laryngeal cancer treated with primary radiotherapy versus primary laryngectomy

BACKGROUND

The purpose of this study was to determine the clinical outcomes of T4 laryngeal cancers.

METHODS

T4 laryngeal cancers treated with curative intent from January 2003 to December 2010 were analyzed. Outcomes were evaluated in both primary radiotherapy (+/- chemotherapy) (RT/CRT) and primary surgery cohorts.

RESULTS

Among the 65 primary RT/CRT and 42 primary surgery patients included, median follow-up was 4.4 years. There was a trend for improved locoregional control with surgery (74% vs 88%; p = .08). In the RT/CRT group the 3-year laryngectomy-free survival was 67%. The 2-year gastrostomy dependency rate was 23% with RT/CRT versus 6% with primary surgery (p = .07). Overall survival (OS) at 3 years was significantly lower in the RT/CRT versus primary surgery group (41% vs 70%; p < .01).

CONCLUSION

Laryngeal preservation is achieved in over two thirds of patients with primary RT/CRT. Patients with low volume minimal cartilage involvement T4 disease may be best suited to RT/CRT. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2035-E2040, 2016.

Computed Tomography Virtual Bronchoscopy: Normal Variants, Pitfalls, and Spectrum of Common and Rare Pathology

A broad spectrum of pathologies that involve the laryngotracheobronchial airway and imaging plays a crucial role in evaluating these abnormalities. Computed tomography with virtual bronchoscopy has been found to be very helpful in defining the location, extent, and nature of these lesions, and is increasingly being used even in patients with contraindications for fiberoptic bronchoscopy and laryngoscopy. Ionizing radiation, associated with virtual bronchoscopy, can be minimized by using low-dose multidetector computed tomography and hybrid iterative reconstruction techniques. Furthermore, retrospectively generated virtual bronchoscopy from a routinely acquired computed tomography data set eliminates additional cost and radiation. In the future, virtual bronchoscopy assisted with advanced navigational techniques will broaden the diagnostic and therapeutic landscape. This article presents the characteristic features of common and rare laryngotracheobronchial pathologies seen with virtual bronchoscopy.

Tumor volumetry as a prognostic factor in the management of T4a laryngeal cancer

OBJECTIVES/HYPOTHESIS

The role of tumor volume in T4a laryngeal cancer remains unclear among different treatment modalities. Using tumor volumetry, we investigated the impact of primary tumor volume on this subset of patients.

STUDY DESIGN

Retrospective cohort study of 62 T4a laryngeal cancer patients.

METHODS

From October 2002 to September 2010, 48 patients were treated with definitive chemoradiation therapy (CRT), and 14 patients had undergone total laryngectomy. Tumor volume was calculated and was correlated with the overall survival (OS), progression-free survival (PFS), and local control rate (LCR) data of each treatment group.

RESULTS

The 5-year OS, PFS, and LCR were significantly lower in the CRT group with tumor volume ≥ 15 cm(3) (22.5% vs. 48.7%, P = 0.009; 32.2% vs. 64.3%, P = 0.003; 45.2% vs. 67.3%, P = 0.039). Multivariate analysis showed that tumor volume was an independent poor prognosticator for OS, PFS, and LCR in the CRT group. For tumor volume ≥ 15 cm(3) , total laryngectomy provided a significantly higher 5-year OS and PFS (54.5% vs. 22.5%, P = 0.039; 80.0% vs. 32.2%, P = 0.017) than for those tumors treated with definitive CRT.

CONCLUSIONS

Patients with T4a laryngeal cancer with primary tumor volume ≥ 15 cm(3) had poorer survival outcomes after definitive CRT compared with total laryngectomy. It was also an independent poor prognosticator on LCR, PFS, and OS for those receiving definitive CRT. For patients with tumor volume ≥ 15 cm(3), total laryngectomy provided a better survival outcome than definitive CRT.

Comparing primary tumors and metastatic nodes in head and neck cancer using intravoxel incoherent motion imaging: a preliminary experience

OBJECTIVE

This study aimed to use intravoxel incoherent motion (IVIM) imaging for investigating differences between primary head and neck tumors and nodal metastases and to evaluate IVIM efficacy in predicting outcome.

METHODS

Sixteen patients with head and neck cancer underwent IVIM diffusion-weighted imaging on a 1.5-T magnetic resonance imaging scanner. The significance of parametric difference between primary tumors and metastatic nodes were tested. Probabilities of progression-free survival and overall survival were estimated using the Kaplan-Meier method.

RESULTS

In comparison with metastatic nodes, the primary tumors had significantly higher vascular volume fraction (f) (P < 0.0009) and lower diffusion coefficient (D) (P < 0.0002). Patients with lower SD for D had prolonged progression-free survival and overall survival (P < 0.05).

CONCLUSIONS

Pretreatment IVIM measures were feasible in investigating the physiologic differences between the 2 tumor tissues. After appropriate validation, these findings might be useful in optimizing treatment planning and improving patient care.

Imaging in laryngeal cancers

Imaging plays an important complementary role to clinical examination and endoscopic biopsy in the evaluation of laryngeal cancers. A vast majority of these cancers are squamous cell carcinomas (SCC). Cross-sectional imaging with contrast-enhanced computed tomography (CT) and magnetic resonance (MR) imaging allows excellent depiction of the intricate anatomy of the larynx and the characteristic patterns of submucosal tumor extension. CT, MRI and more recently PET-CT, also provide vital information about the status of cervical nodal disease, systemic metastases and any synchronous malignancies. Additionally, certain imaging-based parameters like tumor volume and cartilaginous abnormalities have been used to predict the success of primary radiotherapy or surgery in these patients. Integration of radiological findings with endoscopic evaluation greatly improves the pretherapeutic staging accuracy of laryngeal cancers, and significantly impacts the choice of management strategies in these patients. Imaging studies also help in the post-therapeutic surveillance and follow-up of patients with laryngeal cancers. In this article, we review the currently used laryngeal imaging techniques and protocols, the key anatomic structures relevant to tumor spread and the characteristic patterns of submucosal extension and invasion of laryngeal cancer. The role of CT, MRI and PET-CT in the evaluation of patients with laryngeal SCC and the impact of imaging findings on prognosis and clinical management is also discussed.

Laryngeal tumor volume as a predictor for thyroid cartilage penetration

BACKGROUND

Review of laryngectomy specimens demonstrated that preoperative CT scanning is suboptimal in predicting both thyroid cartilage penetration and extralaryngeal spread. We investigated the association between the CT-based gross tumor volume (GTV) with pathologic evidence of thyroid cartilage penetration among patients undergoing laryngectomy for squamous cell carcinoma (SCC) of the larynx.

METHODS

Ninety-four patients were identified who underwent total laryngectomy for SCC of the larynx. GTV, as defined by preoperative diagnostic CT scan, was contoured and analyzed using treatment-planning software.

RESULTS

Among the 49 nonirradiated patients, the mean GTVs of patients with (n = 15) and without (n = 34) thyroid cartilage penetration was 60.1 and 28.0 cm(3) (p = .004). When the nonirradiated patients were divided into 3 GTV groups (≤25 cm(3), 25-50 cm(3), >50 cm(3)), the rates of thyroid cartilage penetration were 23%, 17%, and 78%, respectively (p = .003).

CONCLUSIONS

Laryngeal tumor volume is associated with pathologic evidence of thyroid cartilage penetration in nonirradiated patients.

Dynamic contrast-enhanced magnetic resonance imaging as a predictor of outcome in head-and-neck squamous cell carcinoma patients with nodal metastases

PURPOSE

Dynamic contrast-enhanced MRI (DCE-MRI) can provide information regarding tumor perfusion and permeability and has shown prognostic value in certain tumors types. The goal of this study was to assess the prognostic value of pretreatment DCE-MRI in head and neck squamous cell carcinoma (HNSCC) patients with nodal disease undergoing chemoradiation therapy or surgery.

METHODS AND MATERIALS

Seventy-four patients with histologically proven squamous cell carcinoma and neck nodal metastases were eligible for the study. Pretreatment DCE-MRI was performed on a 1.5T MRI. Clinical follow-up was a minimum of 12 months. DCE-MRI data were analyzed using the Tofts model. DCE-MRI parameters were related to treatment outcome (progression-free survival [PFS] and overall survival [OS]). Patients were grouped as no evidence of disease (NED), alive with disease (AWD), dead with disease (DOD), or dead of other causes (DOC). Prognostic significance was assessed using the log-rank test for single variables and Cox proportional hazards regression for combinations of variables.

RESULTS

At last clinical follow-up, for Stage III, all 12 patients were NED. For Stage IV, 43 patients were NED, 4 were AWD, 11 were DOD, and 4 were DOC. K(trans) is volume transfer constant. In a stepwise Cox regression, skewness of K(trans) (volume transfer constant) was the strongest predictor for Stage IV patients (PFS and OS: p <0.001).

CONCLUSION

Our study shows that skewness of K(trans) was the strongest predictor of PFS and OS in Stage IV HNSCC patients with nodal disease. This study suggests an important role for pretreatment DCE-MRI parameter K(trans) as a predictor of outcome in these patients.

Head and neck cancers on CT: preliminary study of treatment response assessment based on computerized volume analysis

OBJECTIVE

The objective of our study was to investigate the feasibility of computerized segmentation of lesions on head and neck CT scans and evaluate its potential for estimating changes in tumor volume in response to treatment of head and neck cancers.

MATERIALS AND METHODS

Twenty-six CT scans were retrospectively collected from the files of 13 patients with 35 head and neck lesions. The CT scans were obtained from an examination performed before treatment (pretreatment scan) and an examination performed after one cycle of chemotherapy (posttreatment scan). Thirteen lesions were primary site cancers and 22 were metastatic lymph nodes. An experienced radiologist (radiologist 1) marked the 35 lesions and outlined each lesion's 2D contour on the best slice on both the pre- and posttreatment scans. Full 3D contours were also manually extracted for the 13 primary tumors. Another experienced radiologist (radiologist 2) verified and modified, if necessary, all manually drawn 2D and 3D contours. An in-house-developed computerized system performed 3D segmentation based on a level set model.

RESULTS

The computer-estimated change in tumor volume and percentage change in tumor volume between the pre- and posttreatment scans achieved a high correlation (intraclass correlation coefficient [ICC] = 0.98 and 0.98, respectively) with the estimates from manual segmentation for the 13 primary tumors. The average error in estimating the percentage change in tumor volume by automatic segmentation relative to the radiologists' average error was -1.5% +/- 5.4% (SD). For the 35 lesions, the ICC between the automatic and manual estimates of change in pre- to posttreatment tumor area was 0.93 and of percentage change in pre- to posttreatment tumor area was 0.85. The average error in estimating the percentage change in tumor area by automatic segmentation was -3.2% +/- 15.3%.

CONCLUSION

Preliminary results indicate that this computerized segmentation system can reliably estimate changes in tumor size on CT scans relative to radiologists' manual segmentation. This information can be used to calculate changes in tumor size on pre- and posttreatment scans to assess response to treatment.

Polydimethylsiloxane: An effective immune adjuvant and slow-release cytokine medium for local cancer treatment

Background and Aim

Silicone oil or gel has well-defined chemotactic properties on monocytes and lymphocytes in vivo. It results in fibrotic reaction when spread into the human tissues either incidentally or purposely and can slowly release any physically-enclosed lyophilized compounds due to its viscosity. Our aim is to investigate whether polydimethylsiloxane could be considered as an effective medium in the local treatment of cancer.

Materials and Methods

Our study was conducted between January 2004 and December 2006 on 15 patients with various types of cancer. The criteria for selection included patients with locally-advanced tumor that was rapidly growing and life threatening and those who had poor quality of life and general wellbeing. The patients were already discharged from the cancer centre before joining the study, after they had already received their chemoradiation protocol. Once a week for one month, different areas of the tumor were injected with 0.25 ml of polydimethylsiloxane medical grade (viscosity: 350 centistokes at 30°C), mixed with 300,000 units of lyophilized human IL-2. Tumor biopsies were taken before the study was started and one week after the last injection for the histopathological analysis of the percentage of severe inflammatory reaction using an image analysis system. CT scans of the tumor were taken before the injection cycle was started and one week after the last injection in order to determine the percentage change in the size of the tumor. The quality of life and general wellbeing of the patients was assessed at the beginning of the stud, and one week after the study was over by using the Karnofsky performance test.

Results

Our treatment was well tolerated by the patients. They had a significant improvement in their quality of life and general well being (p = 0.0005). The prognosis of the patients before the beginning of the study ranged between 1 and 6 months, while their overall survival after treatment was between 2 and 12 months, with three patients still remaining alive. A significant decrease in the tumor size was observed at the end of the study in 12 patients (p < 0.0001). Such a decrease was associated with a significant increase in the percentage of the tumor containing a severe immune reaction (p <0.0001). A significant correlation was found between the percentage reduction in tumor size and the percentage of tumor immune reaction (r² = 0.968; p < 0.0001).

Conclusion

Polydimethylsiloxane could be used as an effective cytokine medium in the local treatment of cancer. When injected inside the tumor, it is capable of creating and modulating an effective, slow and persistent antitumor immune response. Moreover, it is capable of improving the overall survival as well as the quality of life and general well being of the cancer patients.

Laryngeal cancer: how does the radiologist help?

The radiologist makes a valuable contribution to the staging of laryngeal cancer and this has a direct influence on treatment planning. This review focuses on the main anatomical concepts, patterns of tumour spread and how to detect this with optimal cross sectional imaging. Issues surrounding the relationship of tumour to the ventricular complex, submucosal laryngeal spaces, anteroposterior extension, laryngeal cartilage involvement and metastatic spread are discussed and illustrated. The impact of these imaging findings on the array of therapeutic options is described.

Interobserver reliability of computed tomography-derived primary tumor volume measurement in patients with supraglottic carcinoma

BACKGROUND

Prior studies have determined that macroscopic ("gross") tumor volume (GTV), as calculated from pretreatment computer tomography (CT), was capable of predicting local control in squamous cell carcinoma arising in different subsites in the head and neck in patients who were treated with nonsurgical organ-preservation therapy. The majority of these studies were single-institution, retrospective investigations. Consequently, there has been concern that GTV measurements may not be reproducible by different readers at different institutions. The objective of the current study was to measure the interobserver reliability for GTV measurements for squamous cell carcinoma of the supraglottic larynx (SGSCCA) performed by different readers at different institutions.

METHODS

Eight experienced readers (4 neuroradiologists and 4 radiation oncologists) from different institutions independently measured the pretreatment GTV of 20 patients with SGSCCA. The CT scans were obtained from patients entered into the definitive radiation therapy arm of Radiation Therapy Oncology Group protocol 91-11, who had supraglottic carcinoma and underwent pretreatment CT scans of the neck. Statistical analysis focused on interobserver reliability as measured by the intraclass correlation coefficient.

RESULTS

The intraclass correlation coefficient was 0.81 (95% lower confidence bound, 0.71). This value was interpreted as "excellent."

CONCLUSIONS

GTV measurements were reliable and reproducible when performed by neuroradiologists and radiation oncologists who were experienced in the interpretation of CT scans of the extracranial head and neck in patients with SGSCCA. The result implied that the correlation between GTV and local control should be reproducible across institutions.

Laryngeal imaging

Knowing the surgical options for treating laryngeal carcinomas and the factors that are used to select patients for radiation therapy leads to a more valuable and relevant interpretation of neck scans in patients with laryngeal tumors. Critical factors include tumor volume; cartilaginous invasion; spread across supraglottic-glottic-subglottic boundaries; infiltration of preepiglottic, paraglottic, and pharyngeal planes; and nodal disease. MR imaging offers greater sensitivity to cartilaginous invasion than CT but shows a higher rate of false-positive studies. Direct coronal MR imaging is often valuable in assessing these issues.

c-met overexpression in supraglottic laryngeal squamous cell carcinoma and its relation to lymph node metastases

BACKGROUND

The c-met oncogene encodes the receptor for the hepatocyte growth factor/scatter factor (HGF/SF), which is known to have the effects of stimulation of cell motility, dissociation of epithelial sheets, invasion of cellular matrix, and induction of angiogenesis. Many studies in solid tumors have indicated a role for c-met and HGF/SF in the progression of the disease.

METHODS

The expression of c-met in tissue specimens was studied by immunohistochemical examination in 60 patients with supraglottic laryngeal squamous cell carcinoma. Patients were chosen such that there were 30 with lymph node metastases in the neck and 30 without metastases. TNM staging, differentiation, lymphovascular and perineural invasion, and growth pattern for tumors were also recorded, and their relation to lymph node metastases was analyzed.

RESULTS

Overexpression of c-met was observed in 90% of the cases at the primary site and in 83% of the cases with lymph node metastases in the neck. Lymphovascular invasion (P = 0.005) and the N stage (P = 0.001) were found to be related to lymph node metastases, but other variables-c-met overexpression, the T stage, perineural invasion, and growth pattern-were found to have no relation to lymph node metastases in multivariate analysis of the data with linear regression.

CONCLUSIONS

c-met overexpression is observed in both the primary site and the neck in supraglottic laryngeal squamous cell carcinoma. We believe that it may have a role in the progression of malignancy, but we were unable to find a definite relation between c-met expression and lymph node metastases.

Does delay in starting treatment affect the outcomes of radiotherapy? A systematic review

PURPOSE

The objective of this study was to synthesize what is known about the relationship between delay in radiotherapy (RT) and the outcomes of RT.

METHODS

A systematic review of the world literature was conducted to identify studies that described the association between delay in RT and the probability of local control, metastasis, and/or survival. Studies were classified by clinical and methodologic criteria and their results were combined using a random-effects model.

RESULTS

A total of 46 relevant studies involving 15,782 patients met our minimum methodologic criteria of validity; most (42) were retrospective observational studies. Thirty-nine studies described rates of local recurrence, 21 studies described rates of distant metastasis, and 19 studies described survival. The relationship between delay and the outcomes of RT had been studied in diverse situations, but most frequently in breast cancer (21 studies) and head and neck cancer (12 studies). Combined analysis showed that the 5-year local recurrence rate (LRR) was significantly higher in patients treated with adjuvant RT for breast cancer more than 8 weeks after surgery than in those treated within 8 weeks of surgery (odds ratio [OR] = 1.62, 95% confidence interval [CI], 1.21 to 2.16). Combined analysis also showed that the LRR was significantly higher among patients who received postoperative RT for head and neck cancer more than 6 weeks after surgery than among those treated within 6 weeks of surgery (OR = 2.89; 95% CI, 1.60 to 5.21). There was little evidence about the impact of delay in RT on the risk of metastases or the probability of long-term survival in any situation.

CONCLUSION

Delay in the initiation of RT is associated with an increase [corrected] in LRR in breast cancer and head and neck cancer. Delays in starting RT should be as short as reasonably achievable.

Laryngeal imaging

Knowing the surgical options for treating laryngeal carcinomas and the factors that are used to select patients for radiation therapy leads to a more comprehensive interpretation of neck scans in patients with laryngeal tumors (Table 6). Critical factors include tumor volume; cartilaginous invasion; spread across supraglottic-glottic-subglottic [table: see text] boundaries; infiltration of preepiglottic, paraglottic, and pharyngeal planes; and nodal disease. MR imaging offers greater sensitivity to cartilaginous invasion than CT but leads to a high rate of false-positive studies, which decreases its overall accuracy. Thin-section CT with multiplanar capability is competitive with direct coronal MR scanning and benefits from high specificity and submillimeter section thickness, if multidetector units are employed. Overall, the head and neck radiologist plays an invaluable role in assessing the extent of disease and therefore influences the appropriate selection from the available treatment options.

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

PURPOSE

To evaluate different contrast material volumes, flow rates, and start delays for contrast material enhancement of neck structures and squamous cell carcinoma to determine the most effective examination protocol.

MATERIALS AND METHODS

Seventy patients with squamous cell carcinoma were prospectively randomized into four groups for examination with different protocols (125 mL of contrast material administered at a flow rate of 2.5 mL/sec, 100 mL at 2.0 mL/sec, 90 mL at 1.5 mL/sec, or 70 mL at 1.0 mL/sec). Dynamic series were performed on the tumors and relevant anatomic structures to obtain time-attenuation curves. The protocols were compared (analysis of variance and Tukey-Kramer tests) with regard to time and level of maximum tumor enhancement and carotid arterial enhancement of more than 150 HU. One selected protocol was tested in 30 additional routine examinations with start delays of 40 seconds (for laryngeal and/or hypopharyngeal tumors, 3-mm collimation) and 45 seconds (for oropharyngeal tumors, 5-mm collimation).

RESULTS

Except for the 70-mL bolus administered at 1.0 mL/sec, the other protocols performed similarly well, yielding comparable maximum tumor enhancement at 52 seconds and later. In spite of a smaller volume of 90 mL, due to the prolonged flow time at 1.5 mL/sec, carotid arterial enhancement of more than 150 HU was prolonged (when compared with that in 100- or 125-mL protocols). As a result of these circumstances, injection of 90 mL at 1.5 mL/sec was considered more effective, providing no significant differences in tumor (P =.39) or carotid arterial (P =.52) enhancement between routine examinations and dynamic series.

CONCLUSION

A single bolus of 90 mL administered at 1.5 mL/sec appears to be the most desirable protocol for contrast enhancement.