Amit Mehndiratta

• M.B.B.S, M.M.S.T, DPhil.(Oxon)
• Professor (Assistant) at Indian Institute of Technology Delhi

The objective was to modulate the resistance of a hand-held device, e.g., joystick, for customizing a rehabilitative therapeutic patient-centric virtual environment protocol. Two similar sets of springs (each set having three springs with graded rigidness) were customized to increase the handle-resistance. The springs were experimentally calibrated...

Lung cancer is a significant contributor to global cancer-related fatalities. Utilizing deep learning techniques has the potential to enhance the early detection of lung nodules in thoracic computed tomography (CT) scans, facilitating effective diagnosis and treatment planning. Moreover, given the three�dimensional (3D) nature of thoracic CT sc...

Predictive performance of penalty-based IVIM analysis methodologies BE+TV and BE+HPF for response to Neoadjuvant Chemotherapy have been evaluated using clinical dataset with osteosarcoma in comparison with existing IVIM analysis methods. IVIM datasets before and after chemotherapy were analyzed using 5 IVIM analysis methods – Bi-exponential model a...

Maximum diameter and volume of the tumour provide important clinical information and aredecision‑making parameters for patients suspected with prostate cancer (PCa). The objectives of thisstudy were to develop an automated method for 3D tumour measurement and compare it with theradiologist’s manual assessment, as well as to investigate the impact o...

Background Prostate Imaging-Reporting and Data System version 2.1 (PI-RADS v2.1) was developed to standardize the interpretation of multiparametric MRI (mpMRI) for prostate cancer (PCa) detection. However, a significant inter-reader variability among radiologists has been found in the PI-RADS assessment. The purpose of this study was to evaluate th...

Reproducibility and repeatability of penalty-based IVIM analysis methodologies BE+TV and BE+HPF have been evaluated using clinical dataset with osteosarcoma in comparison with existing IVIM analysis methods. IVIM datasets at three time-points during chemotherapy were analyzed and healthy muscle tissue was used as local control for IVIM analysis and...

Objective To implement an advanced spatial penalty-based reconstruction to constrain the intravoxel incoherent motion (IVIM)–diffusion kurtosis imaging (DKI) model and investigate whether it provides a suitable alternative at 1.5 T to the traditional IVIM–DKI model at 3 T for clinical characterization of prostate cancer (PCa) and benign prostatic h...

The aim of this study was to investigate the potential of Intravoxel incoherent motion (IVIM) parameters to predict event-free-survival (EFS) in patients with localized osteosarcoma treated by chemotherapy. Quantitative and IVIM parameter estimation and histogram analysis was performed in tumor volume at baseline. Imaging parameters along with clin...

The spin relaxation time (T1) of the water protons, an intrinsic property of tissue, can be a useful marker of therapeutic response in osteosarcoma. T1 values were estimated in whole tumor volume before and after completion of chemotherapy and histogram analysis was performed to characterize tumor T1 and its changes in the course of chemotherapy. R...

Automated classification of significant prostate cancer (PCa) using MRI plays a potential role in assisting in clinical decision-making. Multiparametric MRI using a machine-aided approach is a better step to improve the overall accuracy of diagnosis of PCa. The objective of this study was to develop and validate a framework for differentiating Pros...

Accuracy and consistency in RECIST(Response evaluation criteria in solid tumors) measurements are crucial as it directly impacts patient treatment options. Manual RECIST measurement, requiring high expertise & attention, is time-expensive, prone-to-error, operator-subjective. we propose an automated tumor segmentation and RECIST score estimation me...

Recently texture analysis(TA) of MR images has also shown promising results in evaluating response to therapy in different types of cancer. TA uses mathematical approach to characterize the spatial distribution of signal intensity variations in an image and extracts quantitative features thus may infer clinically relevant information about tissue m...

Histopathological examination is the current gold standard for evaluating tumor response to anti-cancer therapy; though it is possible only after surgery. Non-invasive imaging biomarkers of tumor response to therapy may be useful in optimizing existing treatments improving overall outcome. The spin-lattice relaxation time of water protons (T1) refl...

Radiological based qualitative assessment of evaluated IVIM parametric maps using state-of-the-art IVIM analysis methods Bi-exponential (BE) model with adaptive Total Variation Penalty function (BE+TV) and BE with adaptive Huber Penalty function (BE+HPF) has been performed in comparison to the commonly used IVIM analysis methodologies like BE model...

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents. Monitoring treatment response during chemotherapy might help in better and personalized therapeutic options improving overall therapeutic outcome. RECIST1.1 is the standard imaging based non-invasive treatment response evaluation criteria in solid tumors....

The occurrence of brain tumor is increasing; it is believed that early detection will prove to be beneficial for its treatment. IVIM has proved to provide valuable information and has been explored for brain tumor in prior studies. In the following study, IVIM analysis for brain tumor detection was performed using a novel Biexponential model with T...

Osteosarcoma is a primary malignant bone tumor in children and adolescents with significant morbidity and poor prognosis. Diffusion weighted imaging (DWI) plays a crucial role in diagnosis and prognosis of this malignant disease by capturing cellular changes in tumor tissue early in the course of treatment without any contrast injection. Segmentati...

Objective Histopathological examination (HPE) is the current gold standard for assessing chemotherapy response to tumor, but it is possible only after surgery. The purpose of the study was to develop a noninvasive, imaging-based robust method to delineate, visualize, and quantify the proportions of necrosis and viable tissue present within the tumo...

Conventional analysis of motor-evoked potential (MEP) is performed in time domain using amplitude and latency, which encapsulates information relevant to the cortical excitability of the brain. The study investigated the importance of time-frequency analysis by comparing MEPs in time-frequency domains (TFD) of healthy versus stroke survivors. Six h...

Robots have the potential to help provide exercise therapy in a repeatable and reproducible manner for stroke survivors. To facilitate rehabilitation of the wrist and fingers joint, an electromechanical exoskeleton was developed that simultaneously moves the wrist and metacarpophalangeal joints. The device was designed for the ease of manufacturing...

In this paper, we identify factors which improve the quality of technical education using the data from World Bank’s Technical Education Quality Improvement Programme (TEQIP) in India. We evaluate the success of TEQIP in improving the quality of technical education in the country. Our findings show significant impact of this intervention on the qua...

Tables 9 and 10 in the original article contained a typographical error. The corrected Tables 9 and 10 are now given next page.

Purpose: To explore the role of quantitative Intravoxel incoherent motion (IVIM) parameters and their histogram analysis in characterizing changes in Osteosarcoma receiving neoadjuvant chemotherapy (NACT) and evaluating therapeutic response. Methods: Forty patients (N = 40; Male:Female = 30:10; Age = 17.7 ± 5.9years; Metastatic:localized = 17:23...

Objective To investigate the effect of number and combination of b values used on the accuracy of estimated Intravoxel Incoherent Motion (IVIM) parameters using simulation and clinical data. Materials and methods Simulations with seven combinations of b values were performed for 4, 6, 8, and 13 numbers of b values with six different values of D, D...

Automatic and accurate segmentation of osteosarcoma region in MRI images can assist doctor to prepare a feasible treatment plan, hence resulting in improved cure rate. The purpose of this study was to evaluate and compare the performance of automated and semi-automated algorithms that might be effective in segmenting bone tumor in MRI data, with re...

Osteosarcoma is a highly morbid bone-tumor with poor prognosis. Neoadjuvant-chemotherapy(NACT) is the current standard of care. The response of NACT is judged on Histopathology-examination(HPE) after surgical resection of tumor. However, a non-invasive and accurate methods for evaluation of treatment response during the course of therapy is highly...

Histological necrosis is the current gold standard for response evaluation in osteosarcoma treated with neoadjuvant chemotherapy (NACT). However it is applicable only after tumor resection on completion of NACT. Thus, a non-invasive early marker of NACT response is desirable. We performed NACT response prediction and evaluation using Intra-voxel In...

Purpose High mortality rate due to liver cirrhosis has been reported over the globe in the previous years. Early detection of cirrhosis may help in controlling the disease progression toward hepatocellular carcinoma (HCC). The lack of trained CT radiologists and increased patient population delays the diagnosis and further management. This study pr...

Purpose The purpose of this paper is to create a hierarchy of critical success factors affecting the higher technical education institutions, taking a case study of India. Using total interpretive structural modeling (TISM), the paper attempts to establish the inter-linkages among ten critical success factors for enhancing the performance of these...

Osteosarcoma(OS) and Ewing’s sarcoma family of tumors(ESFT) are the most common primary malignant bone tumor in children and adolescents. As the patient’s age, presenting signs & symptoms and qualitative imaging features are common in both, there could be a diagnostic dilemma that can only be resolved by biopsy & histopathological assessment. Textu...

Quantitative analysis of Intravoxel incoherent motion (IVIM) effect of diffusion weighted imaging can assess both diffusion and perfusion component of tissue separately. To the best of our knowledge, IVIM analysis in primary bone tumors has not been reported yet and no reference for IVIM parameter values in bone tumors is available for simulation s...

There has been a lot of work in segmentation of tumors in organs like the brain. Segmentation of bone tumor with MRI is not widely studied. Manual segmentation can be costly and time consuming. We study three automatic 3D segmentation techniques: Energy-based graph cuts, deep feed forward neural networks and mean shift clustering. Results show that...

Proper Delineation of the tumour boundary and assessment of tumour size can take crucial part in treatment planning and monitoring treatment response. We investigate a fully automated Simple linear iterative clustering (SLIC) superpixel-based method for detection and segmentation of pathological tissues like oedema, tumour and necrosis associated w...

Techniques for lung nodule examination are strongly dependent on the size of the suspected lesion. In patients without risk factors for malignancy, lung nodules of ≤6 mm are regarded as unspecific. CT examinations are usually performed in pulmonary nodules ≤5 mm surrounded by lung parenchyma, since PET and MRI examinations are more reasonable in le...

Purpose: Quantitative analysis in Intra-voxel Incoherent Motion (IVIM) imaging commonly uses voxel-wise estimation of the bi-exponential model, which might not be reliable for clinical interpretation. Improving model fitting performance and qualitative and quantitative parametric estimation, two novel methodologies are proposed here. Methods: Fi...

Histological necrosis is the current gold standard for response evaluation in Osteosarcoma treated with neoadjuvant chemotherapy (NAC). However it is applicable only after tumour resection on completion of NAC. Thus, a non-invasive early marker of NAC response is desirable. We performed NAC response evaluation using Intra-voxel Incoherent Motion (I...

Diffusion weighted imaging (DWI) plays a crucial role in diagnosis and prognosis of cancerous diseases. Proper demarcation of tumour on DWI is therefore necessary for qualitative assessment as well as quantitative image analysis like ADC or IVIM. Manual demarcation of tumour on each DWI slice is time consuming, prone to error and hard to reproduce....

Texture analysis (TA) uses mathematical approach to characterize the spatial distribution of signal intensity variations in an image, and extracts quantitative information that are otherwise imperceptible qualitatively. Good soft tissue contrast of MRI facilitates TA to produce promising results in diagnosis and prognosis. Diffusion Weighted (DW) M...

Accurate demarcation of tumors on DWI MRimages could play a crucial role in diagnosis and prognosis when using quantitative image analysis like ADC or IVIM. Manual demarcation of tumour on each slice of a 3D stack is usually not feasible. Automated or semi-automated methods of segmentation are thus desirable specifically for DWimages that can be us...

Quantitative analysis of IVIM effect revels both diffusion and perfusion component of tissue. As widely used bi-exponential model is not very reliable, we propose two penalty function: a) Total Variation and b) Huber Penalty function with bi-exponential model for IVIM parametric analysis of soft tissue tumours. Results show better fit to IVIM datas...

More than one decade ago, introduction of integrated PET/CT scanners changed oncologic imaging and oncologic patient management profoundly. With these systems, the metabolic information acquired by PET can be anatomically localized even to small structures such as small primary tumors, lymph nodes, and soft tissue masses owing to the high-resolutio...

In order to derive brain haemodynamic parameters such as CBF and the residue function, DSC-MRI analysis typically involves a deconvolution problem. If the blood-brain barrier is disrupted, these parameters are artificially modified due to contrast agent (CA) leakage. In this work, a model free, non-parametric deconvolution method was modified (mCPI...

This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 × 25 × 18 cm(3). Four-dimensional...

Bolus dispersion in DSC-MRI can lead to errors in cerebral blood flow (CBF) estimation by up to 70% when using singular value decomposition analysis. However, it might be possible to correct for dispersion using two alternative methods: the vascular model (VM) and control point interpolation (CPI). Additionally, these approaches potentially provide...

India has a diverse geographical landscape and predominately rural population. Telemedicine is identified as one of the technological pillars to support healthcare services in this region, but is associated with high cost and complex infrastructure, thus restricting its wider use. Mobile-based healthcare (m-Health) services may provide a practical,...

PurposeAn exponential residue function is commonly used in numerical simulations to assess the accuracy of perfusion quantification using dynamic susceptibility contrast (DSC) MRI. Although this might be a reasonable assumption for normal tissue, microvascular hemodynamics are likely to be significantly altered in pathology. Thus the exponential fu...

QUASAR arterial spin labeling (ASL) permits the application of deconvolution approaches for the absolute quantification of cerebral perfusion. Currently, oscillation index regularized singular value decomposition (oSVD) combined with edge-detection (ED) is the most commonly used method. Its major drawbacks are nonphysiological oscillations in the i...

Purpose: Dynamic susceptibility contrast (DSC) perfusion images are contaminated by contributions from macro vascular signal arising from contrast agent within the larger arteries that do not contribute directly to the local tissue perfusion. Methods: A vascular model of the DSC perfusion signal was extended by the inclusion of a macro vascular...

Brain tumors are among the leading causes of tumor-related deaths globally; hence considerable research effort is being expended to improve the patient outcome. There are now multiple imaging techniques available for the diagnosis and management of brain tumors in clinical practice, as well as different contrast agents. All these coupled with amino...

To noninvasively diagnose disease and to describe response to therapy regarding morphology (e.g., size, structure) and (patho)physiology (e.g., blood perfusion) as well as cell function optimal image contrast is key. In our various body compartments in vivo contrast can be altered and improved by changing its intensity and distribution over time. T...

Nuclear medicine is a special division of nuclear physics that deals with the application of radioactivity in diagnostic and therapeutic medicine. This chapter will elaborate the basics of nuclear physics, concepts of nuclear imaging radioactive tracers used in nuclear imaging, and their mechanism. Radiation safety is a major concern while administ...

CONCLUSION Our results demonstrate the unique advantages of fpVCT in evaluation of neurovascular pathologies in terms of higher spatial resolution, dynamic imaging, and superior metal artifact profile. BACKGROUND With the advent of high resolution flat-panel volumetric CT (fpVCT), an isotropic resolution of 150μm3 can be achieved. Neurovascular a...

PURPOSE 4D angiography provides both morphological and functional information about the vasculature. Since the volume of interest (VOI) is irradiated multiple times, concerns about high radiation dose have prevented its routine clinical adoption. This first-in-man pilot study evaluates potential dose savings from prior-image constrained compressed...

CONCLUSION High-resolution dynamic imaging using fpVCT is uniquely suited for pre- and post-surgical evaluation of lower limb ischemia. BACKGROUND Invasive digital subtraction angiography (DSA) is the current gold-standard in pre-surgical vascular planning. This study demonstrates the clinical feasibility of non-invasive 4D angiography using a fla...

DSC-MRI analysis is based on tracer kinetic theory and typically involves the deconvolution of the MRI signal in tissue with an arterial input function (AIF), which is an ill-posed inverse problem. The current standard singular value decomposition (SVD) method typically underestimates perfusion and introduces non-physiological oscillations in the r...

Detection and resection of small neuroendocrine tumours (NET) is like finding a needle in a hay stack. Use of specific tracers such as (68)Ga-DOTATOC in a PET/CT study has been proven to have a high sensitivity and specificity to cells expressing somatostatin-SSR receptors. The use of (99m)Tc-Octreotide to detect neuroendocrine tumours during surge...

We evaluated the rate of successful characterization of gastroenteropancreatic neuroendocrine tumors (NETs) present with an increased somatostatin receptor, comparing CE-CT with CE-MRI, each in correlation with DOTATOC-PET. 8 patients with GEP-NET were imaged using CE-MRI (Gd-EOB-DTPA), CE-CT (Imeron 400) and DOTATOC-PET. Contrast-enhancement of no...

PURPOSE Radiolabeled somatostatin analogs plays an emerging role in the therapy of patients with neuroendocrine tumors (NET). Escalation steps differ in the way of administration, the half-life and ionization effect of the used radionuclides. Because functional imaging approaches with contrast-enhanced ultrasound (CEUS) can detect changes in perfus...

Recently introduced fpVCT scanners can capture volumetric (4D) time-varying projections enabling whole-organ dynamic CTA imaging. The main objective of this study was to assess the temporal resolution of dynamic CTA in discriminating various phases of rapid and slow time-dependent neurovascular pathologies in animal models. Animal models were creat...

In the present case study, improvement of auditory hallucinations following transcranial magnetic stimulation (TMS) therapy was investigated with respect to activation changes of the auditory cortices. Using functional magnetic resonance imaging (fMRI), activation of the auditory cortices was assessed prior to and after a 4-week TMS series of the l...

OBJECTIVE: Previous functional magnetic resonance imaging (fMRI) studies in which visuo-spatial working memory tasks (n-back) were applied, demonstrated that task performance and cerebral activation may depend on factors such as training effects, age and clinical status. The present study aimed to investigate the temporal stability of cerebral act...

Evaluation of brain lesions using magnetic resonance imaging (MRI) provides information that is critical for accurate diagnosis, prognosis, therapeutic intervention and monitoring response. Conventional contrast-enhanced MR neuroimaging using gadolinium (Gd) contrast agents primarily depicts disruption of the blood-brain barrier, demonstrating loca...

To evaluate low-dose contrast-enhanced magnetic resonance angiography (CE-MRA) at high temporal and spatial resolution for imaging of abdominal vascular structures. Contrast-enhanced magnetic resonance angiography (TWIST [time-resolved angiography with interleaved stochastic trajectories]) was performed in 8 male New Zealand white rabbits at 3 T us...

Purpose: Generation of graspable three-dimensional objects applied for surgical planning, prosthetics and related applications using 3D printing or rapid prototyping is summarized and evaluated. Materials and methods: Graspable 3D objects overcome the limitations of 3D visualizations which can only be displayed on flat screens. 3D objects can be...

Purpose: The purpose of this study was to evaluate the diagnostic value and tumor-vascular display properties (microcirculation) of two different functional MRI post-processing and display (color and gray-scale display) techniques used in oncology. Materials and methods: The study protocol was approved by the IRB and written informed consent was...

To evaluate the feasibility of fusion of morphologic and functional imaging modalities to facilitate treatment planning, probe placement, probe re-positioning, and early detection of residual disease following radiofrequency ablation (RFA) of cancer. Multi-modality datasets were separately acquired that included functional (FDG-PET and DCE-MRI) and...

Three-dimensional image reconstruction by volume rendering and rapid prototyping has made it possible to visualize anatomic structures in three dimensions for interventional planning and academic research. Volumetric chest computed tomography was performed on a healthy volunteer. Computed tomographic images of the larger bronchial branches were seg...

In vitro studies have shown that the 3-Tesla (T) magnetic resonance (MR) characteristics of high- and standard-molar gadolinium-based contrast agents differ. Such differences may indicate that high-molar (1.0 M) agents offer advantages for perfusion-weighted imaging (PWI) at 3T, as has been previously reported at 1.5 T. To investigate possible intr...

Malignant mesothelioma (MM) of the pleura is an aggressive and often fatal neoplasm. Because MM frequently demonstrates marked angiogenesis, it may be responsive to antiangiogenic therapy, but effective methods for selecting and monitoring of patients are further needed. We employed dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and...

In January, 2007, a 54-year-old man was referred to our clinic, with the request that we fi nd his primary tumour. 2 months previously, he had noticed that he could not raise his right arm above the horizontal. In December, 2006, the patient saw an orthopaedic specialist, by which time he had also noticed that he was losing weight. MRI of the neck...

PURPOSE/AIM High-quality volume rendering of CT data produces appealing views of the human body. While commercial workstations are designed to support diagnostics or therapy planning, our in-house developed web-based software tool AnatomyMap serves educational purposes. CONTENT ORGANIZATION Data is displayed in 2D and 3D views together with labels...