Anatomic Malformations of the Middle and Inner Ear in 22q11.2 Deletion Syndrome: Case Series and Literature Review.

BACKGROUND AND PURPOSE: The 22q11.2 deletion syndrome is characterized by a heterogenic phenotype, including hearing loss. The underlying cause of hearing loss, especially sensorineural hearing loss, is not yet clear. Therefore, our objective was to describe anatomic malformations in the middle and inner ear in patients with 22q11.2 deletion syndrome. MATERIALS AND METHODS: A retrospective case series was conducted in 2 tertiary referral centers. All patients with 22q11.2 deletion syndrome who had undergone CT or MR imaging of the temporal bones were included. Radiologic images were evaluated on predetermined parameters, including abnormalities of the ossicular chain, cochlea, semicircular canals, and vestibule. RESULTS: There were 26 patients (52 ears) with a CT or MR imaging scan available. A dense stapes superstructure was found in 18 ears (36%), an incomplete partition type II was suspected in 12 cochleas (23%), the lateral semicircular canal was malformed with a small bony island in 17 ears (33%), and the lateral semicircular canal and vestibule were fused to a single cavity in 15 ears (29%). CONCLUSIONS: Middle and inner ear abnormalities were frequently encountered in our cohort, including malformations of the lateral semicircular canal.

Inter-observer agreement in GTV delineation of bone metastases on CT and impact of MR imaging: A multicenter study.

BACKGROUND AND PURPOSE: The use of Stereotactic Body Radiotherapy (SBRT) for bone metastases is increasing rapidly. Therefore, knowledge of the inter-observer differences in tumor volume delineation is essential to guarantee precise dose delivery. The aim of this study is to compare inter-observer agreement in bone metastases delineated on different imaging modalities. MATERIAL AND METHODS: Twenty consecutive patients with bone metastases treated with SBRT were selected. All patients received CT and MR imaging in treatment position prior to SBRT. Five observers from three institutions independently delineated gross tumor volume (GTV) on CT alone, CT with co-registered MRI and MRI alone. Four contours per imaging modality per patient were available, as one set of contours was shared by 2 observers. Inter-observer agreement, expressed in generalized conformity index [CIgen], volumes of contours and contours center of mass (COM) were calculated per patient and imaging modality. RESULTS: Mean GTV delineated on MR (45.9±52.0cm3) was significantly larger compared to CT-MR (40.2±49.4cm3) and CT (34.8±41.8cm3). A considerable variation in CIgen was found on CT (mean 0.46, range 0.15-0.75) and CT-MRI (mean 0.54, range 0.17-0.71). The highest agreement was found on MRI (mean 0.56, range 0.20-0.77). The largest variations of COM were found in anterior-posterior direction for all imaging modalities. CONCLUSIONS: Large inter-observer variation in GTV delineation exists for CT, CT-MRI and MRI. MRI-based GTV delineation resulted in larger volumes and highest consistency between observers.

Functional Imaging in Radiotherapy in the Netherlands: Availability and Impact on Clinical Practice.

AIMS: Functional imaging with positron emission tomography/computed tomography (PET/CT) and multiparametric magnetic resonance (mpMR) is increasingly applied for radiotherapy purposes. However, evidence and experience are still limited, and this may lead to clinically relevant differences in accessibility, interpretation and decision making. We investigated the current patterns of care in functional imaging for radiotherapy in the Netherlands in a care evaluation study. MATERIALS AND METHODS: The availability of functional imaging in radiotherapy centres in the Netherlands was evaluated; features available in >80% of academic and >80% of non-academic centres were considered standard of care. The impact of functional imaging on clinical decision making was evaluated using case questionnaires on lung, head/neck, breast and prostate cancer, with multiple-choice questions on primary tumour delineation, nodal involvement, distant metastasis and incidental findings. Radiation oncologists were allowed to discuss cases in a multidisciplinary approach. Ordinal answers were evaluated by median and interquartile range (IQR) to identify the extent and variability of clinical impact; additional patterns were evaluated descriptively. RESULTS: Information was collected from 18 radiotherapy centres in the Netherlands (all except two). PET/CT was available for radiotherapy purposes to 94% of centres; 67% in the treatment position and 61% with integrated planning CT. mpMR was available to all centres; 61% in the treatment position. Technologists collaborated between departments to acquire PET/CT or mpMR for radiotherapy in 89%. All sites could carry out image registration for target definition. Functional imaging generally showed a high clinical impact (average median 4.3, scale 1-6) and good observer agreement (average IQR 1.1, scale 0-6). However, several issues resulted in ignoring functional imaging (e.g. positional discrepancies, central necrosis) or poor observer agreement (atelectasis, diagnostic discrepancies, conformation strategies). CONCLUSIONS: Access to functional imaging with PET/CT and mpMR for radiotherapy purposes, with collaborating technologists and multimodal delineation, can be considered standard of care in the Netherlands. For several specific clinical situations, the interpretation of images may benefit from further standardisation.

Imaging findings of the orbital and intracranial complications of acute bacterial rhinosinusitis.

UNLABELLED: In patients with acute bacterial rhinosinusitis severe orbital and intracranial complications can occur. This review will illustrate the anatomic relationship between the paranasal sinuses and the orbital and intracranial compartments. Subsequently, the spectrum of orbital and intracranial complications of rhinosinusitis and related imaging findings will be discussed and illustrated by case material from daily practice. TEACHING POINTS: • Acute bacterial rhinosinusitis can cause severe orbital and intracranial complications. • If orbital or intracranial complications are suspected, cross-sectional imaging is mandatory. • Infection can spread from the ethmoid sinus to the orbit through the lamina papyracea. • Frontal sinusitis can spread intracranially through dehiscences or osteomyelitis. • Radiologists must recognize imaging findings of complications of acute bacterial rhinosinusitis.

Detection of extranodal spread in head and neck cancer with [18F]FDG PET and MRI: improved accuracy?

AIM: Preoperative detection of extranodal spread (ENS) in head and neck cancer can have important consequences for patient management. The aim of this study was to determine whether 18-fluorodeoxyglucose positron emission tomography ([18F]FDG PET) or a combination with Magnetic Resonance Imaging (MRI) could more accurately predict ENS, especially with the near availability of fully integrated [18F]FDG PET/MRI scanners. METHODS: In retrospective cohort design a total of twelve patients, with 18 lymphnode metastases were studied with [18F]FDG PET and MRI. Presence of ENS was scored on MRI, and [18F]FDG PET images using a SUV max cut-off point of 12. Histopathology results were used as reference standard. Sensitivity, specificity and accuracy were calculated. RESULTS: The sensitivity, specificity and accuracy of [18F]FDG PET for ENS reached 70%,100% and 83%, respectively. The mean SUVmax of ENS positive lymphnodes was 13.6 versus 8.7 for lymphnode metastases without ENS (P=0.03). The sensitivity, specificity and accuracy of MRI for ENS were 70%, 100% and 83%, respectively. When the [18F]FDG PET and MRI findings were combined sensitivity, specificity and accuracy were 80%, 100% and 89%, respectively. Thus, accuracy increased from 83% to 89%. CONCLUSION: When there is no ENS or doubt of ENS on MRI, [18F]FDG PET seems to have additional value since it improves sensitivity and resolves uncertainty in case of high FDG uptake. This benefit needs to be confirmed prospectively in a larger cohort.

Vocal cord paralysis: anatomy, imaging and pathology.

UNLABELLED: Vocal cord paralysis (VCP) can be caused by any process that interferes with the normal function of the vagal nerves or recurrent laryngeal nerves. It may be a first sign of extensive and severe pathology. Radiologists must therefore be able to recognise the imaging findings of VCP and know the course of the vagal and recurrent laryngeal nerves. This review focuses on the anatomy and imaging evaluation of these nerves and thereby the possible sites for pathology causing VCP. The imaging characteristics and imaging mimics of VCP are discussed and cases from daily practice illustrating causes of VCP are presented. TEACHING POINTS: • Vocal cord paralysis may be the first presentation of severe pathology. • Radiologists must be aware of imaging characteristics and mimics of vocal cord paralysis. • Lesions along the vagal nerves and recurrent laryngeal nerves can cause vocal cord paralysis.

Importance of tumor volume in supraglottic and glottic laryngeal carcinoma.

PURPOSE: The aim of our study was to assess the prognostic value of tumor volume compared to and in addition to T-stage on local control (LC), disease-free survival (DFS), and overall survival (OS) in glottic and supraglottic laryngeal carcinoma patients. PATIENTS AND METHODS: In 150 patients, we determined tumor volume on diagnostic CT scans. We applied crude and multivariable Cox regression analysis to relate volume (continuous), T-stage and the combination to 5-year DFS, OS, and LC. Before, we examined the linearity assumption of the association between volume and outcome with restricted cubic spline functions. Prognostic performance of the models was examined by determination of the model's discrimination. Discriminative ability was determined with the C statistic referring to the ability to discriminate between patients who do and do not develop an event during follow-up. RESULTS: A strong association between tumor volume and DFS and OS was found. The restricted cubic spline plot did not indicate a non-linear relationship between tumor volume and DFS and local control. Tumor volume demonstrated a better discriminative ability to predict DFS and OS compared to T-stage (0.68 and 0.57 vs. 0.59 and 0.54, respectively). For local control, T-stage showed a higher discriminative ability than tumor volume (0.63 vs. 0.61). The combined model increased discriminative power (0.69). CONCLUSION: Volume seems to be more important than T-stage in prediction of DFS or OS in laryngeal squamous cell carcinoma patients. Perhaps prediction of DFS, OS, and LC could be improved by including tumor volume into the staging process.

Value of MR and CT Imaging for Assessment of Internal Carotid Artery Encasement in Head and Neck Squamous Cell Carcinoma.

Objective. This study was conducted to assess the value of CT and MR imaging in the preoperative evaluation of ICA encasement. Methods. Based upon three patient groups this study was performed. Retrospective analysis of 260 neck dissection reports from 2001 to 2010 was performed to determine unexpected peroperative-diagnosed encasement. Two experienced head and neck radiologists reviewed 12 scans for encasement. Results. In four out of 260 (1.5%) patients undergoing neck dissection, preoperative imaging was false negative as there was peroperative encasement of the ICA. Of 380 patients undergoing preoperative imaging, the radiologist reported encasement of the ICA in 25 cases. In 342 cases no encasement was described, 125 of these underwent neck dissection, and 2 had encasement peroperatively. The interobserver variation kappa varied from 0.273 to 1 for the different characteristics studied. Conclusion. These retrospectively studied cohorts demonstrate that preoperative assessment of encasement of the ICA using MRI and/or CT was of value in evaluation of ICA encasement and therefore contributively in selecting operable patients (without ICA encasement), since in only 1.5% encasement was missed. However, observer variation affects the reliability of this feature.

Improved depiction of pterygopalatine fossa anatomy using ultrahigh-resolution magnetic resonance imaging at 7 tesla.

PURPOSE: To study the anatomy of the pterygopalatine fossa (PPF) using ultrahigh-resolution magnetic resonance imaging. METHODS: A human cadaveric tissue block containing the pterygopalatine fossa was examined on a clinical 7-Tesla magnetic resonance imaging system. Subsequently, cryosections of the tissue block were created in a coronal plane. The cryosections were photographed and collected on adhesive tape. The on-tape sections were stained for Mallory-Cason, in order to detail the anatomic structures within the fossa. Magnetic resonance images were compared with surface photos of the tissue block and on-tape sections. RESULTS: High-resolution magnetic resonance images demonstrated the common macroscopic structures in the PPF. Smaller structures, best viewed at the level of the operation microscope, which have previously been obscured on magnetic resonance imaging, could be depicted. Some of the orbital pterygopalatine ganglion branches and the pharyngeal nerve were clearly viewed. CONCLUSIONS: In our experience with one human cadaver specimen, magnetic resonance imaging at 7 Tesla seems effective in depicting pterygopalatine fossa anatomy and provides previously unseen details through its demonstration of the pharyngeal nerve and the orbital pterygopalatine ganglion branches. The true viability of depicting the pterygopalatine fossa with ultrahigh-resolution MR will depend on confirmation of our results in larger studies.

Prognostic significance of radiologically determined neck node volume in head and neck cancer: a systematic review.

This systematic review addresses the prognostic significance of neck node volume in head and neck cancer. Primary tumor volume evolved as an independent significant factor for survival in head and neck cancer patients. Besides primary tumor volume, multiple prognostic features related to the regional lymph nodes were studied in literature. In literature, some authors showed the significance of total tumor volume/nodal volume for survival and loco-regional control. Articles reporting prognosis and survival in nodal tumor volumes were collected by systematically reviewing publications listed in the Pubmed and Embase databases. Publications were included when they at least reported on total tumor volume (TTV) or nodal volume and survival. In this systematic review we studied 21 articles. For measurement of nodal volume different formulas were used. Until now, there's no clear statistical evidence for the use of either TTV or nodal volume versus primary tumor volume to predict the individual loco-regional control or survival after treatment. There is wide variety of tumor measuring systems in the literature. The cut-off value for local tumor response also shows large variation. Firstly consensus should be accomplished on standardization of volume measurements, preferably automatic, and secondly large study groups are needed with identical treatment modalities to further unravel the role of neck node volume as separate staging tool.

The prognostic value of abnormal findings on radiographic swallowing studies after total laryngectomy.

Pharyngocutaneous fistulae are a common complication after total laryngectomy. Our study evaluates the correlation of postoperative radiographic swallowing studies and clinical symptoms. We also propose a grading system to classify leaks radiographically. The records of 45 patients who underwent total laryngectomy were retrospectively reviewed. All patients had a radiographic swallowing study (RSS) on or around the tenth postoperative day. A grading system was developed to classify radiographic findings (grade 0-5). Twenty-two patients had an abnormal RSS (grade 2-5). Three patients (13.6%) had clinical signs of impending fistula whereas radiography showed moderate leakage (grade 3) in one patient and a pharyngocutaneous fistula (grade 5) in two. The other 19 patients with radiographically demonstrated leakage had no clinical signs of anastomotic complications. After total laryngectomy, radiography may reveal anastomotic complications of varying severity. The grading system used in this study enabled us to objectively classify the radiological abnormalities on swallowing studies. Because most radiographic leakages were clinically silent and not all clinically apparent fistula were radiographically visible in our study, the role of routine postoperative radiographic swallowing studies in the absence of clinical signs or fistula remains unclear.

The significance of circumscribed malignant mammographic masses in the surveillance of BRCA 1/2 gene mutation carriers.

Breast cancers in gene mutation carriers may escape mammographic detection because of rapid growth and tumor expansion. Therefore, they may mimic benign lesions on the mammogram. Twenty-nine BRCA 1/2 mutation carriers under surveillance developed 31 breast cancers between 1994 and 2001 at a mean age of 44.2 years. Controls were 63 women with 67 breast cancers in the same period at a mean age of 53.8 years, also under surveillance because of a life time risk of at least 15%. In 26% of the carriers vs. 48% of the controls, mammography was the method that first suspected a malignancy. Seven radiologists performed a retrospective review of the original mammograms to establish technical assessment, with special attention for circumscribed lesions and estimated probability of malignancy. In the mutation carriers seven (23%) circumscribed non-calcified mammographic masses were found and three in the controls (4.5%) P=0.01. These masses were proven to be malignant. In both groups around 70% of these fast-growing circumscribed lesions were detected by the patients. The masses were situated in breasts with a good interpretable breast pattern. BRCA 1/2 mutation carriers had a significantly higher percentage of circumscribed non-calcified mammographic masses that proved to be malignant. These mammographic lesions in women at high risk should be described as at least Birads 0 and worked-up with ultrasound and needle biopsy.

Occult primary tumors of the head and neck: accuracy of thallium 201 single-photon emission computed tomography and computed tomography and/or magnetic resonance imaging.

OBJECTIVE: To determine the accuracy of thallium 201 single-photon emission computed tomography (thallium SPECT) and computed tomography and/or magnetic resonance imaging (CT/MRI) in the detection of occult primary tumors of the head and neck. DESIGN: Study of diagnostic tests. SETTING: National Cancer Institute, Amsterdam, the Netherlands. PATIENTS AND METHODS: Thirty-two patients with a neck node metastasis of an epithelial tumor and negative findings by mirror examination at initial presentation were included in the study. Twenty-nine patients underwent thallium SPECT and CT/MRI before examination under general anesthesia (EUA). In 3 patients only thallium SPECT was performed before EUA. Histological confirmation of an occult primary tumor during EUA was used as the gold standard. Negative radiodiagnostic and nuclear findings in the upper aerodigestive tract in the presence of a primary carcinoma other than of the head and neck were interpreted as true-negative findings. RESULTS: For thallium SPECT the following results were recorded: sensitivity, 67%; specificity, 69%; accuracy, 69%; positive predictive value, 33%; and negative predictive value, 90%. In 1 patient, thallium whole body scan indicated a primary carcinoma beyond the mucosal lining of the upper aerodigestive tract. The CT/MRI results were as follows: sensitivity, 71%; specificity, 73%; accuracy, 72%; positive predictive value, 45%; and negative predictive value, 89%. CONCLUSIONS: Thallium SPECT and CT/MRI showed comparable results for detection of occult primary tumors of the head and neck. A potential advantage of thallium SPECT is that it allows total body screening.

Laryngeal or hypopharyngeal squamous cell carcinoma: can follow-up CT after definitive radiation therapy be used to detect local failure earlier than clinical examination alone?

PURPOSE: To determine if follow-up computed tomography (CT) after definitive radiation therapy for laryngeal or hypopharyngeal (laryngopharyngeal) carcinoma allows the detection of local failure earlier than clinical examination alone. MATERIALS AND METHODS: Pre- and post-radiation therapy follow-up CT scans in 66 patients were reviewed retrospectively. All patients underwent definitive hyperfractionated radiation therapy and were followed up clinically for at least 2 years after its completion. Post-radiation therapy CT scans (N = 153) were evaluated for posttreatment changes with a three-point score: A score of 1 represented expected posttreatment changes; 2, focal mass with a maximal diameter of less than 1 cm and/or asymmetric obliteration of laryngeal tissue planes; or 3, focal mass with a maximal diameter equal to or greater than 1 cm or estimated tumor volume reduction of less than 50%. All patients underwent the first posttreatment CT study 1-6 months after therapy. New or progressive laryngeal cartilage changes were noted. The clinical impression of the larynx at the time of each follow-up CT scan was also recorded. RESULTS: In 12 of 29 (41%) patients with treatment failure at the primary site, follow-up CT scans were definite for local failure (score, 3) a mean of 5.5 months (median, 3.5 months; range, 1-17 months) before clinical examination results. CONCLUSION: In many patients, follow-up CT shows local failure earlier than does clinical examination alone.

Pre- and post-radiotherapy computed tomography in laryngeal cancer: imaging-based prediction of local failure.

PURPOSE: To determine if pre-radiotherapy (RT) and/or post-radiotherapy computed tomography (CT) can predict local failure in patients with laryngeal carcinoma treated with definitive RT. METHODS AND MATERIALS: The pre- and post-RT CT examinations of 59 patients (T3 glottic carcinoma [n = 30] and T1-T4 supraglottic carcinoma [n = 29]) were reviewed. For each patient, the first post-RT CT study between 1 and 6 months after irradiation was used. All patients were treated with definitive hyperfractionated twice-daily continuous-course irradiation to a total dose of 6,720-7,920 cGy, and followed-up clinically for at least 2 years after completion of RT. Local control was defined as absence of primary tumor recurrence and a functioning larynx. On the pre-treatment CT study, each tumor was assigned a high-or low-risk profile for local failure after RT. The post-RT CT examinations were evaluated for post-treatment changes using a three-point post-RT CT-score: 1 = expected post-RT changes; 2 = focal mass with a maximal diameter of < 1 cm and/or asymmetric obliteration of laryngeal tissue planes; 3 = focal mass with a maximal diameter of > 1 cm, or < 50% estimated tumor volume reduction. RESULTS: The local control rates at 2 years post-RT based on pre-treatment CT evaluation were 88% for low pre-treatment risk profile patients (95% CI: 66-96%) and 34% (95% CI: 19-50%) for high pre-treatment risk profile patients (risk ratio 6.583; 95% CI: 2.265-9.129;p = 0.0001). Based on post-treatment CT, the local control rates at 2 years post-RT were 94% for score 1, 67% for score 2, and 10% for score 3 (risk ratio 4.760; 95% CI: 2.278-9.950 p = 0.0001). Post-RT CT scores added significant information to the pre-treatment risk profiles on prognosis. CONCLUSIONS: Pre-treatment CT risk profiles, as well as post-RT CT evaluation can identify patients, irradiated for laryngeal carcinomas, at high risk for developing local failure. When the post-RT CT score is available, it proves to be an even better prognosticator than the pre-treatment CT-risk profile.

Imaging of squamous cell carcinoma of the hypopharynx.

The hypopharynx is a clinically silent area and early lesions may be asymptomatic for a long period. At presentation, primary squamous cell carcinoma of this area is usually advanced. Almost all of these lesions are studied with imaging as part of the clinical work-up. The goal of this article is to help the practicing radiologist convey a report which provides information that will directly influence treatment of patients with hypopharyngeal carcinoma.

CT findings in chondroradionecrosis of the larynx.

PURPOSE: Our goal was to describe the CT findings before and after radiation therapy in a series of patients with laryngeal chondroradionecrosis. METHODS: The CT studies obtained before and after radiation therapy in nine patients with the diagnosis of laryngeal chondroradionecrosis were reviewed retrospectively. RESULTS: CT scans revealed abnormalities in all patients. A variable degree of laryngeal soft-tissue swelling was seen in eight of the patients. In four patients, cartilaginous abnormalities were visible initially, and appeared in three of four other patients who had further follow-up CT studies. Six patients had involvement of the thyroid cartilage; collapse of the thyroid cartilage was seen in two cases and gas bubbles were visible adjacent to the thyroid cartilage in three cases. Four patients with involvement of the thyroid cartilage eventually underwent total laryngectomy, and one died suddenly in severe respiratory distress. In all three patients with arytenoidal involvement, anterior dislocation of this cartilage was seen; in two of these patients, the adjacent part of the cricoid cartilage showed some sclerosis. Two patients with arytenoidal necrosis (both with cricoidal sclerosis) kept a functional larynx. In one case, cricoidal sclerosis was seen in association with lysis of the thyroid cartilage. CONCLUSION: The CT appearance of laryngeal chondroradionecrosis is nonspecific, but the diagnosis can be strongly suggested in cases of sloughing of the arytenoid cartilage, fragmentation and collapse of the thyroid cartilage, and/or in the presence of gas bubbles around the cartilage.

Computed tomography for the detection of neck node metastases in melanoma patients.

AIMS: To assess the value of CT scanning for detection of lymph node metastases in the neck. METHODS: The appearance and site of the metastases was studied, as well as the sensitivity and specificity of CT. RESULTS: Nodal metastases did not always show a high contrast uptake and nodal density therefore cannot be used as a criterion for metastasis. Irregular contrast enhancement was seen in seven of the 21 tumour-positive necks. Frequently, metastases in the parotids, superficial nodes in the neck and in the posterior triangle were seen. The sensitivity and specificity of palpation and CT scanning were 87 and 100%, respectively. CONCLUSIONS: However, because small, clinically occult, melanoma metastases were frequently overlooked on CT, the role of this imaging modality in assessing occult metastases remains limited. Based on recent data from literature it is reasonable to speculate that ultrasound guided fine needle aspiration cytology (FNAC) will prove to be more effective than a non-invasive staging procedure of the neck in melanoma patients.

Evaluation of pretreatment computed tomography as a predictor of local control in T1/T2 pyriform sinus carcinoma treated with definitive radiotherapy.

BACKGROUND: This study was undertaken to determine whether pretreatment computed tomography (CT) findings can predict local control in pyriform sinus carcinoma treated with definitive radiotherapy (RT). METHODS: Twenty-three patients with pyriform sinus carcinoma (T1: n = 5; T2: n = 18) were treated with high-dose RT and followed for a minimum of 2 years. Tumor volumes and extent were determined on pretreatment CT studies. The specific CT parameters assessed were analyzed as predictors of local control. RESULTS: There was a significant decrease in local control rate for tumors over 6.5 mL (1 of 4 [25%]) relative to tumors under 6.5 mL (17 of 19 [89%]; p = .021). Sensitivity and specificity for local control using this cutoff were 94% and 60%, respectively. Tumor score, as a measure of anatomic extent, was also found to be a significant predictor of local control (p = .033). The local control rate was not influenced significantly by the presence of "minimal" apex disease (< 10 mm in greatest dimensions as measured on CT) but decreased significantly when "bulk" apex disease (> OR = 10 mm) was present (p = .027). Laryngeal cartilage sclerosis was not a significant predictor of outcome. CONCLUSION: Computed tomography can stratify pyriform sinus carcinomas into groups more or less likely to be locally controlled with definitive RT.

The potential impact of CT-MRI matching on tumor volume delineation in advanced head and neck cancer.

PURPOSE: To study the potential impact of the combined use of CT and MRI scans on the Gross Tumor Volume (GTV) estimation and interobserver variation. METHODS AND MATERIALS: Four observers outlined the GTV in six patients with advanced head and neck cancer on CT, axial MRI, and coronal or sagittal MRI. The MRI scans were subsequently matched to the CT scan. The interobserver and interscan set variation were assessed in three dimensions. RESULTS: The mean CT derived volume was a factor of 1.3 larger than the mean axial MRI volume. The range in volumes was larger for the CT than for the axial MRI volumes in five of the six cases. The ratio of the scan set common (i.e., the volume common to all GTVs) and the scan set encompassing volume (i.e., the smallest volume encompassing all GTVs) was closer to one in MRI (0.3-0.6) than in CT (0.1-0.5). The rest volumes (i.e., the volume defined by one observer as GTV in one data set but not in the other data set) were never zero for CT vs. MRI nor for MRI vs. CT. In two cases the craniocaudal border was poorly recognized on the axial MRI but could be delineated with a good agreement between the observers in the coronal/sagittal MRI. CONCLUSIONS: MRI-derived GTVs are smaller and have less interobserver variation than CT-derived GTVs. CT and MRI are complementary in delineating the GTV. A coronal or sagittal MRI adds to a better GTV definition in the craniocaudal direction.