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Biomedical subjects

Suresh K Mukherji

Publications and source records attributed to Suresh K Mukherji.

At least 19 recordsLinked to original sources
PubMed2007

An evaluation of the variability of tumor-shape definition derived by experienced observers from CT images of supraglottic carcinomas (ACRIN protocol 6658).

PURPOSE: Accurate target definition is considered essential for sophisticated, image-guided radiation therapy; however, relatively little information has been reported that measures our ability to identify the precise shape of targets accurately. We decided to assess the manner in which eight "experts" interpreted the size and shape of tumors based on "real-life" contrast-enhanced computed tomographic (CT) scans. METHODS AND MATERIALS: Four neuroradiologists and four radiation oncologists (the authors) with considerable experience and presumed expertise in treating head-and-neck tumors independently contoured, slice-by-slice, his/her interpretation of the precise gross tumor volume (GTV) on each of 20 sets of CT scans taken from 20 patients who previously were enrolled in Radiation Therapy Oncology Group protocol 91-11. RESULTS: The average proportion of overlap (i.e., the degree of agreement) was 0.532 (95% confidence interval 0.457 to 0.606). There was a slight tendency for the proportion of overlap to increase with increasing average GTV. CONCLUSIONS: Our work suggests that estimation of tumor shape currently is imprecise, even for experienced physicians. In consequence, there appears to be a practical limit to the current trend of smaller fields and tighter margins.

Carcinoma, Squamous Cell↗
PubMed2005

Evaluation of the functional diffusion map as an early biomarker of time-to-progression and overall survival in high-grade glioma.

Diffuse malignant gliomas, the most common type of brain tumor, carry a dire prognosis and are poorly responsive to initial treatment. The response to treatment is typically evaluated by measurements obtained from radiographic images several months after the start of treatment; therefore, an early biomarker of tumor response would be useful for making early treatment decisions and for prognostic information. Thirty-four patients with malignant glioma were examined by diffusion MRI before treatment and 3 weeks later. These images were coregistered, and differences in tumor-water diffusion values were calculated as functional diffusion maps (fDM), which were correlated with the radiographic response, time-to-progression (TTP), and overall survival (OS). Changes in fDM at 3 weeks were closely associated with the radiographic response at 10 weeks. The percentage of the tumor undergoing a significant change in the diffusion of water (V(T)) was different between patients with progressive disease (PD) vs. stable disease (SD) (P < 0.001). Patients classified as PD by fDM analysis at 3 weeks were found to have a shorter TTP compared with SD (median TTP, 4.3 vs. 7.3 months; P < 0.04). By using fDM, early patient stratification also was correlated with shorter OS in the PD group compared with SD patients (median survival, 8.0 vs. 18.2 months; P < 0.01). On the basis of fDM, tumor assessment provided an early biomarker for response, TTP, and OS in patients with malignant glioma. Further evaluation of this technique is warranted to determine whether it may be useful in the individualization of treatment or evaluation of the response in clinical protocols.

Adult↗
PubMed2005

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.

Adult↗
PubMed2005

Selective neck dissection: CT and MR imaging findings.

BACKGROUND AND PURPOSE: Selective neck dissection (SND) has become a common surgical procedure for selectively treating known or potential metastatic nodal disease from head and neck cancer while preserving functional structures. The purpose of this article is to describe the expected CT and MR findings after SND. METHODS: CT (26/27) or MR images (1/27) from 27 consecutive patients treated with SND for either staging or nodal control of head and neck malignancy were retrospectively reviewed by two experienced head and neck radiologists. One patient had bilateral SND. The quantity of deep cervical fat was subjectively assessed, as was patency of the ipsilateral internal jugular vein (IJV) and asymmetry in size and contour of the sternocleidomastoid (SCM), trapezius, and infrahyoid strap muscles. The presence of the submandibular gland was noted. RESULTS: Twenty-seven of 28 necks had marked decrease in fat beneath the SCM muscle. This resulted in the muscle directly abutting the paraspinal muscles in most cases. The SCM muscle contour and size was asymmetric or flattened and atrophic in 16/28 necks. Atrophy of the infrahyoid strap muscles was seen in 8/28 necks. Six of 28 had no detectable IJV, and it was presumably thrombosed. Submandibular gland was not present in 17/28 cases. CONCLUSION: The imaging findings after SND are characteristic and reflect the type of surgery performed. If level I nodes are removed, the submandibular gland is absent. Marked decrease in deep cervical fat is common. Changes in and around the SCM muscle are routinely seen and include posterior and medial displacement of the muscle, distortion and flattening of the muscle, or atrophy, despite surgical preservation of spinal accessory nerve. Finally, although the IJV is not resected in SND, nonvisualization of the vein on postoperative images may reflect thrombosis.

Adult↗
PubMed2004

Cerebral perfusion CT: technique and clinical applications.

Perfusion computed tomography (CT) is a relatively new technique that allows rapid qualitative and quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The technique is based on the central volume principle (CBF = CBV/MTT) and requires the use of commercially available software employing complex deconvolution algorithms to produce the perfusion maps. Some controversies exist regarding this technique, including which artery to use as input vessel, the accuracy of quantitative results, and the reproducibility of results. Despite these controversies, perfusion CT has been found to be useful for noninvasive diagnosis of cerebral ischemia and infarction and for evaluation of vasospasm after subarachnoid hemorrhage. Perfusion CT has also been used for assessment of cerebrovascular reserve by using acetazolamide challenge in patients with intracranial vascular stenoses who are potential candidates for bypass surgery or neuroendovascular treatment, for the evaluation of patients undergoing temporary balloon occlusion to assess collateral flow and cerebrovascular reserve, and for the assessment of microvascular permeability in patients with intracranial neoplasms. This article is a review of the technique, clinical applications, and controversies surrounding perfusion CT.

Blood Volume↗
PubMed2004

Carotid perfusion CT with balloon occlusion and acetazolamide challenge test: feasibility.

Carotid balloon test occlusion (BTO) is used to assess the collateral circulation and cerebrovascular reserve in patients in whom carotid artery occlusion is contemplated. Eight patients in whom the test was successful were evaluated with perfusion computed tomography (CT) in the resting state and after acetazolamide challenge. Three of the patients showed symmetric blood flow and normal response to acetazolamide. One of them underwent permanent carotid occlusion and did not develop any delayed ischemic stroke. The remaining five patients showed asymmetric blood flow. One of them had markedly low blood flow and abnormal response to acetazolamide. The patient developed ipsilateral hemispheric stroke following permanent carotid occlusion after the superficial temporal artery to middle cerebral artery bypass graft occluded. In the other four patients, the steal phenomenon was seen in ipsilateral and contralateral hemispheres. Although definitive quantitative values for perfusion CT are not yet standardized, it may be feasible to predict that the patients with symmetric blood flow and normal acetazolamide-enhanced challenge test results will do well after permanent carotid occlusion. Patients with asymmetric blood flow and abnormal response to the acetazolamide challenge test may require a revascularization procedure to protect them from delayed ischemic stroke.

Acetazolamide↗
PubMed2004

Clinical applications of diffusion tensor imaging.

Directionally-ordered cellular structures that impede water motion, such as cell membranes and myelin, result in water mobility that is also directionally-dependent. Diffusion tensor imaging characterizes this directional nature of water motion and thereby provides structural information that cannot be obtained by standard anatomic imaging. Quantitative apparent diffusion coefficients and fractional anisotropy have emerged from being primarily research tools to methods enabling valuable clinical applications. This review describes the clinical utility of diffusion tensor imaging, including the basic principles of the technique, acquisition, data analysis, and the major clinical applications.

Anisotropy↗
PubMed2004

Dynamic contrast-enhanced MR imaging.

Dynamic contrast-enhanced magnetic resonance imaging is a useful clinical tool in evaluation of soft tissue neoplasm and lymph nodes in head and neck. It is thought to be a useful predictor of response to radiotherapy for head and neck carcinoma and used to monitor the treatment and distinguish post-therapeutic changes from recurrent mass with greater confidence. It can be used to distinguish between normal and malignant tissue and to differentiate a malignant lymphoma from other lymph nodal enlargements. The technique utilizes relative differences in microvasculature and microcirculation between malignant and non-malignant tissue to achieve greater contrast in signal imaging following bolus contrast administration. This article explains the underlying principles and imaging techniques for this new diagnostic tool. The clinical applications and technical challenges are discussed. The future challenges and some contradictions in results are also outlined.

Carcinoma, Squamous Cell↗
PubMed2004

Magnetic resonance spectroscopy of head and neck neoplasms.

Magnetic resonance spectroscopy (MRS) is a validated noninvasive method for evaluation of possible malignant tumor and lymph nodes of the head and neck. From its roots as a budding research application, it has made the critical transition to a widespread clinical tool. MRS analyzes the tissue at a molecular level and searches for the presence of specific metabolites, which are markers for malignancy. Differentiation of benign from malignant neoplasm, detection of recurrence of malignant tumor and noninvasive treatment monitoring of treated or untreated tumor are some of the important utilities of MRS. One dimensional 1H-MRS is the most popular and promising technique for spectroscopic analysis while P-31 MRA and two-dimensional correlated spectroscopy (2D COSY) have also showed some promise. This article describes the application of magnetic resonance spectroscopy for evaluation of malignant tumors of the neck.

Biomarkers, Tumor↗
PubMed2004

Pediatric head and neck masses.

Most neck masses in the pediatric head and neck region are benign. Congenital, developmental, and inflammatory lesions make up most of the masses in the pediatric head and neck. For example, neck masses due to inflammatory lymphadenitis are common in children because of the frequency of upper respiratory tract infections. Although many of the malignant tumors in children are found in the head and neck, they account for only a small portion of the neck masses. The choice of the imaging modality is based on a number of factors, several of which are unique to the pediatric population. Although the bulk of disease entities are adequately evaluated by CT, MRI can provide additional vital information in many cases. MRI provides better soft tissue characterization than CT, has multiplanar capabilities. In this article, we will attempt to provide an overview of conditions that present as neck masses.

Blood Vessels↗
PubMed2004

Magnetic resonance imaging of perineural spread of head and neck malignancies.

Perineural invasion is a common mechanism of spread of head and neck cancers. Imaging plays an important role in detection of this condition because a large number of patients with perineural spread (PNS) are clinically asymptomatic. Accurate detection of PNS requires an understanding of anatomy of commonly involved neural pathways. High level of suspicion on the part of the radiologist, awareness of common imaging signs of PNS and careful attention to imaging technique can aid in earlier detection of this condition.

Aged↗
PubMed2004

MR imaging of brachial plexus.

The brachial plexus is a complex anatomic component originating from ventral rami of the lower cervical nerve roots from C5 to C8 and upper thoracic spinal nerve roots from T1, providing sensory and motor innervation to the upper extremities. As it is inaccessible to palpation, clinical evaluation of the brachial plexus is very challenging and localizing lesions along its course is very difficult. The gamut of pathologic conditions involving the brachial plexus includes primary tumor, direct extension of adjacent tumor, metastasis, trauma, or an inflammatory condition. MR imaging provides superior diagnostic ability due to its ability of multiplanar imaging and greater soft tissue contrast. This article discusses MR imaging findings in a variety of pathologic conditions, with special emphasis on neoplastic process.

Brachial Plexus↗
PubMed2004

Use of cross-sectional imaging in predicting facial nerve sacrifice during surgery for parotid neoplasms.

BACKGROUND: Neoplasms of the parotid gland are difficult management issues because of the wide variation in their biological behavior and the potential for sacrifice of the facial nerve during resection. Because of the significant associated morbidity, prediction of facial nerve sacrifice is critically important for planning surgical procedures and preoperative counseling of patients. We hypothesize that along with the knowledge of the tumor type we would be able to accurately predict the likelihood of facial nerve sacrifice using cross-sectional imaging. METHODS: All patients included in this study were previously untreated patients with parotid neoplasms operated on between January 1997 and July 2002. Only those patients with an available preoperative imaging were included and this resulted in 44 patients for review. Nine patients with preoperative deficits in facial nerve function were excluded from this study since these patients would require facial nerve sacrifice regardless of the radiological prediction. The prediction of facial nerve sacrifice was determined using a prediction of tumor location and an algorithm. The predicted results were compared to the operative record. RESULTS: For all lesions, cross-sectional imaging predicted the need for sacrifice of the facial nerve with a sensitivity of 0.83 (95% CI, 0.36-0.99), specificity of 0.90 (95% CI, 0.72-0.97), PPV of 0.63 (95% CI, 0.26-0.90), and NPV of 0.96 (95% CI, 0.79-0.99). For malignant lesions only, prediction of sacrifice of the facial nerve had a sensitivity of 0.83 (95% CI, 0.36-0.99), specificity of 0.80 (95% CI, 0.51-0.95), PPV of 0.63 (95% CI, 0.26-0.90), and NPV of 0.92 (95% CI, 0.62-0.99). CONCLUSION: Cross-sectional imaging and application of our algorithm is a sensitive method for identifying patients with parotid neoplasms who require facial nerve sacrifice. CT and MRI have a high negative predictive value for facial nerve sacrifice.

Algorithms↗