Magnetic resonance imaging and computed tomography in pediatric head and neck masses

Fifty-three magnetic resonance imaging (MRI) and 25 computed tomography (CT) studies of 53 head and neck masses in pediatric patients were reviewed retrospectively. All lesions had pathologic proof except for 2 metastatic and 2 recurrent lesions, which only had prior pathologic confirmation at their primary sites. These included 12 malignant tumors, 23 benign tumors, 6 inflammatory masses, and 12 congenital lesions. The MRI performance ranged predominantly from good to excellent in detection of the lesion and the extent of involvement and in contrast to the surrounding tissue; when CT comparison was available, MRI proved to be equal to or better than it in detection of these factors and in preoperative diagnosis. Our results suggest that MRI should be the method of choice for the initial evaluation of the pediatric head and neck region, especially in those patients requiring multiple examinations. However, CT and MRI should be used conjunctively in complicated cases, especially those possibly involving lesions with calcifications or bony involvement.     

Magnetic resonance imaging in the diagnosis of nonsquamous tumors of the head and neck

Nonsquamous cell tumors of the head and neck can be reliably evaluated by MRI. In certain pathologic entities, it appears that MRI can provide more information than CT scan.     

Magnetic resonance navigation for head and neck lesions.

OBJECTIVE: Review applications of interventional magnetic resonance imaging and describe methods, procedures, and additional instrumentation for the magnetic resonance "operating theater." Describe advantages of magnetic resonance navigation for biopsies of head and neck tumors. STUDY DESIGN: Patients with palpable and nonpalpable head and neck and cranial base tumors were recruited into the study. Patients underwent magnetic resonance-guided biopsy. Retrospective analysis of 21 patients was conducted. METHODS: 0.5 Tesla superconducting open magnetic resonance imaging was used for navigation of the biopsy needle. Patient records and magnetic resonance images were reviewed. The type, size, and location of the lesions were tabulated. Type of anesthesia and monitoring method were analyzed. The histopathologic correlation was conducted in patients who required further surgeries or open surgical biopsies. RESULTS: Twenty-two biopsies were carried out in the magnetic resonance suite. One patient required general anesthesia and the other biopsies were conducted under intravenous sedation. There was only one case of nonconcurrence in a patient with Wegener's granulomatosis of the posterior orbit. Overall, a 92% concurrence rate between image-directed fine-needle aspiration, open biopsy, and surgical therapy was encountered. No complications occurred. CONCLUSIONS: The use of interventional magnetic resonance imaging to assist with fine-needle aspiration core biopsy has made the biopsy procedure safer and more accurate. Potentially morbid and disfiguring surgeries have been avoided in some patients. Deeper lesions have been more easily approached, as the needle for biopsy is under constant magnetic resonance guidance. Improved visualization for critical structures allows safer performance of biopsies. The primary difficulties of open magnetic resonance imaging relate to the need for nonferromagnetic instrumentation and equipment and their high costs. An inverse relationship exists between the imaging quality and the "dead time" required to acquire images.     

Study of the head and neck position in microlaryngoscopy using magnetic resonance imaging

Several studies have critically analyzed the ideal position for laryngeal exposure during microlaryngoscopy; however, these studies have lacked the ability to evaluate the head and neck position while maintaining a direct view into the airway. Therefore, a newly established two-curve methodology was used to investigate the influence of head and neck position during microlaryngoscopy in MRI images. Fourteen normal adult volunteers were used in this magnetic resonance imaging study. The airway was divided into two curves in the sagittal plane at the center of the airway in three head and neck positions: extension–extension, neutral and flexion–extension position. The airway passage curves, point of inflection and its tangent, the line of laryngoscope, line of hyoid bone and mandible were plotted on each scan. Angles and area formed by these lines were calculated to evaluate the airway morphology changes. The flexion–extension position caused a reduction in the area between the line of laryngoscope and curves, but there was no significant difference between the three positions (p = 0.664). The flexion–extension position also resulted in the lowest angle values for α (angle between the tangent and horizon, p = 0.000), β (between the line of hyoid and horizon, p = 0.002) and δ (between the line of mandible and horizon, p = 0.004). Our study provides a better understanding of the changes in normal airway morphology during microlaryngoscopy in different positions, reinforcing the concept that flexion–extension position is the optimal position for microlaryngoscopy.     

Advances in head and neck imaging

This article discusses new techniques in head and neck imaging.     

喉咽、颈段食管癌的磁共振表现

通过对１７例喉咽、颈食管癌的食管吞钡造影与磁共振（ＭＲＩ）检查结果进行对比分析。资料表明，食管吞钡造影不能显示肿物浸润周围组织结构的情况，故难作出正确的ＴＮＭ分期：ＭＲＩ是显示肿瘤三维形态、肿瘤与邻近结构的有效和可靠的技术手段。提示ＭＲＩ地喉因、颈段食管癌的诊断、ＴＮＭ分期和技术治疗的选择，均具有重要的指导意义。     

Value of magnetic resonance imaging in assessing bone destruction in head and neck lesions

We utilized low-field magnetic resonance imaging (MRI) to evaluate 12 patients with head and neck lesions and suspected skull base or facial bone destruction. All except one had high resolution computed tomography (CT). MRI was performed on a 0.15 tesla (low-field) resistive unit, with routinely good resolution due mainly to the use of specially designed rf receiver coils (surface coils). T1 and T2 weighted spin echo images were performed in all cases. In three instances axial, coronal, and sagittal images were done. All CTs were done with high resolution techniques on state-of-the-art equipment. Comparison of the CT and MR images (at low-field strength) showed that MRI's main strength lies in its freedom to perform images in any plane and to visualize intracranial lesions with early brain involvement. Otherwise, the two modalities are comparable. Bone destruction seen on CT was always detectable on MRI, although CT is clearly superior in resolving bone detail. MRI is recommended when direct coronal CT scans are not obtainable to evaluate superiad tumor extension. The improved visualization of nasopharyngeal soft tissue and cavernous sinus region is likely to make MRI the examination of first choice in evaluating lesions of the nasopharynx, skull base, and cavernous sinus.     

Dynamic contrast-enhanced magnetic resonance imaging in radiotherapeutic efficacy in the head and neck tumors

PURPOSE: The purpose to this study is to identify correlations between pathology and dynamic contrast-enhanced magnetic resonance imaging (MRI) and to assess the utility of this technique in the evaluation of radiation response for head and neck cancer. MATERIALS AND METHODS: MRI was prospectively performed after radiotherapy in 27 patients with various head and neck tumors. After bolus injection of contrast material, a dynamic study was performed using a spoiled gradient-recalled imaging sequence. The maximum slope of increase (MSI) on the time-intensity curve was displayed as a color-coded image. The ratio of MSI (MSIR) was obtained for tumor and normal muscles. Pathological specimens were obtained after MRI in all cases. Histological grading of irradiation changes was classified into 5 grades (0-4). Correlations between MSIR and histological grade were examined. RESULTS: Histologically, 18 tumors were classified as grade 2 (presence of viable tumor cells), 4 were grade 3 (nonviable tumor cells), and 5 were grade 4 (no tumor cells). Although the mean +/- SD of MSIR in patients with histological grade 2 or 3 was 7.4 +/- 7.9, MSIR in patients with grade 4 was 1.8 +/- 0.73, representing a significant difference ( P < .05). Every patient with grade 4 displayed an MSIR of 2.5 or less, although 5 of 22 patients with grade 2 or 3 had an MSIR of 2.5 or less. CONCLUSIONS: MSI quantitatively reflects response to radiotherapy for head and neck cancer. Color-coded MSI display is feasible for depicting permeability changes after radiotherapy.     

Functional magnetic resonance imaging using iron oxide particles in characterizing head and neck adenopathy

OBJECTIVES: In lymph nodes harboring metastases the reticuloendothelial system is replaced by tumor cells and does not concentrate iron particles. This study assesses the value of contrast magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxide particles (Combidex, Advanced Magnetics, Inc., Cambridge, MA) to characterize and stage neck nodes. STUDY DESIGN: Prospective analysis of neck imaging by Combidex MRI, with correlation from pathological assessment of resected lymph nodes. METHODS: Nine patients underwent MRI and subsequent bilateral neck dissections (three), unilateral neck dissections (five) or fine-needle aspiration (one). Each case was evaluated for the number, location, MRI characteristics, and pathological assessment of lymph nodes. RESULTS: Forty-nine separate nodal levels were evaluated with both Combidex MRI and pathological assessment. The presence of metastatic nodal involvement among 45 levels was correctly assessed by the Combidex MRI (three false-negative results, one false-positive result; sensitivity, 84%; specificity, 97%). Analysis was possible for 101 of the individual lymph nodes identified by MRI that could be correlated with individual nodes pathologically examined. Combidex MRI assessment was correct for 99 nodes (one-false positive result, one false-negative result; sensitivity, 95%, specificity, 99%). Standard MRI interpretation without Combidex identified that 12 of 18 nodes (67%) that were greater than or equal to 10 mm (greatest dimension) contained tumor, whereas 9 of 83 nodes (ll%) that were less than 10 mm contained tumor. CONCLUSIONS: Combidex MRI provides functional information to characterize lymph nodes in the clinical staging of squamous cell carcinoma of the head and neck. The inability of MRI to identify small lymph nodes restricts the usefulness of this technique.     

Positron emission tomography (PET) imaging in head and neck cancer

Positron Emission Tomography (PET) with 18F-Fluordeoxyglucose is a diagnostic imaging technique very useful in the management of head and neck cancer, better than anatomic imaging in most cases. PET shows higher diagnostic accuracy in the detection of local and regional tumor recurrences. PET is also indicated for the identification of unknown primary tumors when regional nodal metastasis is the presenting feature. The improved planning of radiation therapy with hybrid cameras PET-CT, the earlier diagnosis of post-radiotherapy residual disease and the possibility of monitoring the effects of chemotherapy makes PET imaging an important tool in evaluating tumor response to treatment.     

New trends in head and neck imaging

Summary The development of novel imaging techniques has exerted a larger influence on medical science than have any other advances in the last decade. The following occurrence are now evident in imaging for all medical disciplines: reduced use of ionizing radiation, abandonment of invasive methods, real-time properties, visualization of functional parameters, digitalization and pooling of information, as well as interaction of user with image information. A wide variety of imaging methods is now available clinically for the study of head and neck diseases. However, only picture archiving and communication systems (PACS) can efficiently handle and integrate information coming from multiple imaging modalities, such as computed tomography, magnetic resonance imaging, positron emission tomography, digital subtraction angiography and digital radiography. Such systems also incorporate image workstations that the surgeon can use for preoperative planning and even perioperative assistance. Current PACS are reviewed, since their future use may change the operating theater and also change surgical strategies.     

Oncogenes in head and neck cancer

Primary head and neck squamous cell carcinomas from 58 patients were analyzed for the presence of alterations in the K-ras, raf, and erb-B oncogenes. Analysis of 17 fresh tumor specimens using sequence analysis of target sequences amplified by the polymerase chain reaction showed no evidence of mutations in the K-ras oncogene. Thirty fresh tumor specimens were analyzed for the presence of raf gene activation using Southern blot analysis. Under these conditions, no mutations in the c-raf oncogene were detected. In this study, 6 (13%) of the 47 tumors studied displayed epidermal growth factor receptor (EGFR) gene amplification and/or gene rearrangement. Overexpression of the erb-B gene was observed in 18 (67%) of the 27 head and neck tumors studied. Those patients expressing high levels of EGFR or showing EGFR amplification had tumors that were clinically more advanced. These data suggest that amplification and over-expression of the EGFR gene may be a useful diagnostic and prognostic marker in head and neck squamous cell carcinomas.     

Cytogenetics in head and neck cancer

Cytogenetics or the study of chromosomes has been an important tool in oncology. It localizes the abnormality on a particular chromosome segment as such but, the molecular analysis on the other hand focuses the exact gene of interest. Hence both are complimentary. Classical cytogenetics in combination with recent molecular techniques has given rise to various molecular cytogenetic analytical techniques such as florescent in-situ hybridization (FISH), spectral karyotyping (SKY) and comparative genomic hybridization (CGH). The role of telomeres and its concerned enzyme telomerase is important in carcinogenesis. This article summarizes the various cytogenetic techniques and presents an overall view of the importance of cytogenetcs in head and neck cancer.