Kunwar S. Bhatia

Shear wave elastography of focal salivary gland lesions: preliminary experience in a routine head and neck US clinic

Book synopsis: New Materialisms rethinks the relevance of materialist philosophy in the midst of a world shaped by forces such as digital and biotechnologies, global warming, global capital, and population flows. Moving away from modes of inquiry that have prioritized the study of consciousness and subjectivity over matter, the essays in this collection show that any account of experience, agency, and political action demands renewed attention to the urgent issues of our own material existence and our environment. The editors propose “new materialisms” as a way to take matter seriously without falling into the conceptual dualism that posits an opposition between matter and thought, materialism and idealism, and body and mind. They locate new materialisms within post-humanist discourses, explaining that new materialist philosophies do not privilege human bodies, but rather view human bodies as one of many bodies, or agential materialities, in the world. By revealing how emerging accounts of matter, materiality, and corporeality are combining with developments in science and technology to demand radically new conceptions of nature, agency, and social and political relationships, New Materialisms makes a significant contribution to the recent resurgence of interest in phenomenology and materialist philosophy in the humanities.

Squamous cell carcinoma of the head and neck: diffusion-weighted MR imaging for prediction and monitoring of treatment response.

ObjectiveTo investigate the role of diffusion-weighted imaging (DWI) in predicting and monitoring chemoradiotherapy response in head and neck squamous cell carcinoma (HNSCC).MethodsDiffusion-weighted imaging was performed pre-treatment (n = 50), intra-treatment (n = 41) and post-treatment (n = 20). Apparent diffusion coefficient (ADC) values were correlated with locoregional failure (LF).ResultsLocoregional failure occurred in 20/50 (40%) patients. A significant correlation was found between LF and post-treatment ADC (p = 0.02) but not pre- or intra-treatment ADC. Serial change in ADC was even more significant (p = 0.00001), using a fall in ADC early (pre- to intra-treatment) or late (intra- to post-treatment) to indicate LF, achieved 100% specificity, 80% sensitivity and 90% accuracy.ConclusionsSingle ADC measurements pre- or intra-treatment did not predict response, but ADC post-treatment was a marker for LF. Serial change in ADC was an even stronger marker, when using an early or late treatment fall in ADC to identify LF.

Head and Neck Squamous Cell Carcinoma: Diagnostic Performance of Diffusion-weighted MR Imaging for the Prediction of Treatment Response

PURPOSE To determine the diagnostic performance of diffusion-weighted (DW) imaging for the prediction of treatment failure in primary head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS The study was approved by the local institutional ethics committee and conducted with informed written consent in patients with primary HNSCC treated with radiation therapy and chemotherapy. DW imaging of the primary tumor was performed before treatment in 37 patients and was repeated within 2 weeks of treatment in 30 patients. Histograms of apparent diffusion coefficients (ADCs) were analyzed, and mean ADC, kurtosis, skewness, and their respective percentage change were correlated for local failure and local control at 2 years by using the Student t test. Univariate and multivariate analyses of the ADC parameters, T stage, and tumor volume were performed by using logistic regression for prediction of local failure. RESULTS Local failure occurred in 16 of 37 (43%) patients and local control occurred in 21 of 37 (57%) patients. Pretreatment ADC parameters showed no correlation with local failure. There was significant intratreatment increase in mean ADC and a decrease in skewness and kurtosis (P < .001, P < .001, P = .024, respectively) for the whole group of patients when compared with those before treatment. During treatment, primary tumors showed a significantly lower increase in percentage change of mean ADC, higher skewness, and higher kurtosis for local failure than for local control (P = .016, .015, and .040, respectively). These ADC parameters also were significant for predicting local failure with use of univariate but not multivariate analysis. CONCLUSION Early intratreatment DW imaging has the potential to allow prediction of treatment response at the primary site in patients with HNSCC.

Evaluation of real-time qualitative sonoelastography of focal lesions in the parotid and submandibular glands: applications and limitations

ObjectiveTo evaluate qualitative ultrasound elastography for focal salivary gland masses identified during routine clinical practice.MethodsSixty-five parotid or submandibular masses in 61 patients underwent real-time qualitative ultrasound elastography and were scored on colour-scaled elastograms in terms of their stiffness relative to adjacent normal salivary parenchyma from ES 1 (soft) to ES 4 (stiff). This was correlated with diagnosis from aspiration cytology or histology.ResultsThere were 29 Warthin’s tumours (WTs), 23 pleomorphic adenomas (PAs), 2 adenoid cystic carcinomas, 1 adenosquamous carcinoma, 1 nodal metastasis from nasopharyngeal carcinoma, 1 lymphoma (2 deposits), 3 Kuttner tumours and 4 cases of Kimura’s disease. ES scores showed clustering according to pathological condition. In this respect, PAs were firmer than WTs (P < 0.004, Fisher’s exact test). Nine, 19, 14 and 17 of the benign masses and 0, 1, 2 and 3 of the malignant masses were ES 1, 2, 3 and 4 respectively. All three primary salivary malignancies were ES 4 compared with 1/29 WTs and 16/23 PAs.ConclusionThese preliminary findings suggest that qualitative real-time ultrasound elastography, although an ancillary technique to conventional ultrasound in the salivary glands, is likely to have a poor ability to discriminate benign lesions (particularly PAs) from malignant disease.

Shear wave elasticity imaging of cervical lymph nodes.

A pilot study of real-time shear wave ultrasound elastography (SWE) for cervical lymphadenopathy in routine clinical practice was conducted on 55 nodes undergoing conventional ultrasound (US) with US-guided needle aspiration for cytology. Elastic moduli of stiffest regions in nodes were measured on colour-coded elastograms, which were correlated with cytology. Malignant nodes (n = 31, 56.4%) were stiffer (median 25.0 kPa, range 6.9-278.9 kPa) than benign nodes (median 21.4 kPa, range 8.9-30.2 kPa) (p = 0.008, Mann Whitney U test). A cut-off of 30.2 kPa attained highest accuracy of 61.8%, corresponding to 41.9% sensitivity, 100% specificity and 0.77 area under the receiver operating characteristic curve. Qualitatively, elastograms of benign nodes were homogeneously soft; malignant nodes were homogeneously soft or markedly heterogeneous with some including regions lacking elasticity signal. SWE is feasible for neck nodes. It appears unsuitable for cancer screening but may detect a subset of malignant nodes. The cause of spatial heterogeneity of malignant nodes on SWE is yet to be established.

Primary Nasopharyngeal Carcinoma: Diagnostic Accuracy of MR Imaging versus that of Endoscopy and Endoscopic Biopsy

PURPOSE To compare the accuracy of magnetic resonance (MR) imaging with that of the current clinical standard of endoscopy and endoscopic biopsy, to determine whether MR imaging depicts subclinical cancers missed at endoscopy and endoscopic biopsy, and to determine whether MR imaging can identify patients without nasopharyngeal carcinoma (NPC) who do not need to undergo invasive sampling biopsy. MATERIALS AND METHODS The study protocol was approved by the institutional review board; written informed consent was obtained from all patients. Patients suspected of having NPC underwent MR imaging, endoscopy, and endoscopic biopsy. Endoscopic biopsy targeted the suspected tumor or sampled the endoscopically normal nasopharynx. The final diagnosis was based on results of the endoscopic biopsy or on results of a repeat biopsy directed at the lesion detected at MR imaging. The sensitivity and specificity of the three investigations were compared by using the Fisher exact test. RESULTS NPC was present in 77 (31%) of 246 patients and absent in 169 (69%) patients. The combined sensitivity, specificity, and accuracy, respectively, were 100%, 93%, and 95% for MR imaging, 90%, 93%, and 92% for endoscopy, and 95%, 100%, and 98% for endoscopic biopsy. Benign disease was mistaken for NPC in 12 (7%) of 169 patients at MR imaging and in 11 (6%) patients at endoscopy. The sensitivity of MR imaging was significantly higher than that of endoscopy (P = .006) and was similar to that of endoscopic biopsy (P = .120). The specificity of MR imaging was similar to that of endoscopy (P = .120) and was significantly lower than that of endoscopic biopsy (P < .001). CONCLUSION MR imaging is an accurate test for the diagnosis of NPC. MR imaging depicts subclinical cancers missed at endoscopy and endoscopic biopsy and helps identify the majority of patients who do not have NPC and who therefore do not need to undergo invasive sampling biopsies.

Real-Time Qualitative Ultrasound Elastography of Cervical Lymph Nodes in Routine Clinical Practice: Interobserver Agreement and Correlation with Malignancy

To evaluate real-time qualitative ultrasound (US) elastography for cervical lymphadenopathy in routine clinical practice, 74 nodes (37 malignant, 37 benign) in 74 patients undergoing sonography underwent US elastography prior to fine needle aspiration for cytology. Dynamic cine loops of elasticity imaging displayed using a chromatic-scale were qualitatively scored by three independent observers for the proportion of stiff areas from ES1-4 (soft to stiff). There was fair to good interobserver agreement as indicated by weighted kappa (κ) statistic from 0.374 to 0.738. Median ES for benign and malignant nodes were 2 and 3 respectively. ES was higher in malignant nodes (p = 0.0003-0.0049, Mann Whitney U tests) although areas under receiver operating characteristic curves (0.68-0.74) indicated suboptimal discrimination. The optimal discriminatory cut-off, ES > 2, achieved only 62.2% sensitivity, 83.8% specificity and 73% accuracy for malignancy. Improvements in reliability and accuracy of real-time qualitative ultrasound elastography are required for it to be adopted into routine clinical practice.

Non-Gaussian analysis of diffusion weighted imaging in head and neck at 3T: a pilot study in patients with nasopharyngeal carcinoma.

Purpose To technically investigate the non-Gaussian diffusion of head and neck diffusion weighted imaging (DWI) at 3 Tesla and compare advanced non-Gaussian diffusion models, including diffusion kurtosis imaging (DKI), stretched-exponential model (SEM), intravoxel incoherent motion (IVIM) and statistical model in the patients with nasopharyngeal carcinoma (NPC). Materials and Methods After ethics approval was granted, 16 patients with NPC were examined using DWI performed at 3T employing an extended b-value range from 0 to 1500 s/mm2. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models on primary tumor, metastatic node, spinal cord and muscle. Non-Gaussian parameter maps were generated and compared to apparent diffusion coefficient (ADC) maps in NPC. Results Diffusion in NPC exhibited non-Gaussian behavior at the extended b-value range. Non-Gaussian models achieved significantly better fitting of DWI signal than the mono-exponential model. Non-Gaussian diffusion coefficients were substantially different from mono-exponential ADC both in magnitude and histogram distribution. Conclusion Non-Gaussian diffusivity in head and neck tissues and NPC lesions could be assessed by using non-Gaussian diffusion models. Non-Gaussian DWI analysis may reveal additional tissue properties beyond ADC and holds potentials to be used as a complementary tool for NPC characterization.

Real-Time Qualitative Ultrasound Elastography of Miscellaneous Non-Nodal Neck Masses: Applications and Limitations

To evaluate real-time qualitative ultrasound elastography as an adjunct to conventional sonography for evaluation of non-nodal neck masses identified in routine clinical practice, 52 consecutive masses in 49 patients underwent both techniques. Lesion stiffness was graded visually on chromatic-scale elastograms from ES0-3 (low to high). Diagnosis was based on (cyto)pathology (11), corroborative cross-sectional imaging (18) or characteristic conventional sonography (23). There were 16 lipomas, 15 lymphatic/venous vascular malformations (LVVMs), six neurogenic tumours/neuromas, five thyroglossal duct cysts (TGCs), five (epi)dermoids, three abscesses, one second-arch branchial cleft cyst (BCC), and one soft-tissue metastasis. In general terms, lesion stiffness was high (ES2-3) for neurogenic tumours/neuromas, (epi)dermoids and metastasis, and low (ES0-1) for lipomas, LVVM, TGCs and BCC. Abscesses displayed variable stiffness according to fluid content. Technical limitations and artefacts of elastograms were identified. Data from real-time qualitative ultrasound elastography may be a useful adjunct to sonography for diagnosis of non-nodal neck masses.

Diagnostic accuracy of diffusion-weighted MR imaging for nasopharyngeal carcinoma, head and neck lymphoma and squamous cell carcinoma at the primary site.

The feasibility of performing diffusion-weighted MRI (DWI) of primary undifferentiated nasopharyngeal carcinoma (NPC) has not been assessed and it is unknown whether the apparent diffusion coefficients (ADC) of primary NPC differs from that of lymphoma or squamous cell carcinoma (SCC) in the head and neck. One hundred patients with newly diagnosed NPC, head and neck lymphoma or SCC underwent echo-planar DWI. ADCs of primary tumours were compared by Kruskal-Wallis test and Mann-Whitney U tests with Bonferroni correction using p<0.05 and p<0.017 respectively to indicate statistical significance. The utility of ADC thresholds for discriminating tumour histology was evaluated by receiver operating characteristic analysis. DWI was successful in 45/65 with NPC, 5/7 with lymphoma and 26/28 with SCC. Mean ADC (+/-SD) of NPC, lymphoma and SCC were 0.98+/-0.161, 0.75+/-0.190, 1.14+/-0.196 (x10(-3)mm(2)/s) respectively which were significantly different (p<0.001-0.003). Optimized ADC thresholds of 0.779, 0.768 and 1.07(x10(-3)mm(2)/s) achieved maximal discriminatory accuracies of 100%, 93% and 70% for SCC/lymphoma, NPC/lymphoma, and SCC/NPC respectively. Echo-planar DWI is a feasible technique for investigating primary NPC although limited in a third of patients due to susceptibility artifacts around the skull base. While the overall ADC value of NPC is significantly different to that of SCC and lymphoma, on a case by case basis overlapping ADCs between these tumours limit its theoretical utility at this site. Nevertheless, DWI may still be useful clinically to distinguish NPC from nasopharyngeal lymphoma in populations with endemic NPC due to the relative rarity of nasopharyngeal SCC.