Oncology

Decision Making in Surveillance of High-Grade Gliomas Using Perfusion MRI as Adjunct to conventional MRI and Artificial Intelligence.

IAG & UCL poster for the 2019 ASCO Annual Meeting

Abstract

BACKGROUND:
Surveillance of High-Grade Gliomas (HGGs) remains a major challenge in clinical neurooncology. Histopathological validation is not an option during the course of disease and imaging surveillance suffers from ambiguous features of both disease progression and treatment related changes. This study aimed to differentiate between Pseudoprogression (PsP) and Progressive Disease (PD) using an artificial intelligence (support vector machine – SVM) classification algorithm.
METHODS:
Two groups of patients with histologically proven HGGs were analysed, a group with a single time point DSC perfusion MRI (45 patients) and a group with multiple time point DSC perfusion MRI (19 patients). Both groups included conventional MRI studies prior and after each perfusion MRI. This study design aimed to replicate decision making in clinical practice including multiple previous studies for each patient. SVM training was performed with all available MRI studies for each group and classification was based on different feature datasets from a single or multiple (subtracted features) time points. Classification accuracy comparisons were performed by calculating prediction error rates for different feature datasets and different time point analyses.
RESULTS:
Our results indicate that the addition of multiple time point perfusion MRI combined with structural (conventional with gadolinium-enhanced sequences) MRI features results in optimal classification performance (median error rate: 0.016, lowest value dispersion). Subtracted feature datasets improved classification performance, more prominently when the final and first perfusion studies were included in the analysis. On the contrary, in the single time point group analysis, structural feature-based classification performed best (median error rate: 0.012).
CONCLUSION:
Validation of our results with a larger patient cohort may have significant clinical importance in optimising imaging surveillance and clinical decision making for patients with HGG.

MRI Findings of Rapidly Progressive Hepatocellular Carcinoma.

Copyright © Copyright 2010 Elsevier Inc. All rights reserved.
Magnetic Resonance Imaging. 2010 Jul;28(6) doi: 10.1016/j.mri.2010.03.005. Epub 2010 Apr 27.

Abstract

PURPOSE:
The purpose of this study is to determine the magnetic resonance imaging (MRI) and patient characteristics in subjects with hepatocellular carcinoma (HCC) that exhibit rapid progression.
MATERIALS AND METHODS:
In this unblinded retrospective study, initial and follow up MR images were reviewed, before and after rapid progression of HCC, respectively. Rapid progression was defined as a lesion <3 cm which exhibited >3 cm increase in one year or 2 cm increase in 6 months. Patient characteristics and MRI findings were determined using clinical information from the institution clinical information system and records from the Radiology and Pathology Departments, Hepatology Division and Liver Transplant Service of the Department of Medicine.
RESULTS:
Seven individuals were identified with HCC that showed rapid progression. Five of the patients had underlying hepatitis C, one had alcoholic hepatitis, and one had immunosuppression due to liver transplantation. On initial MRI, six patients had early intense ring enhancing lesions, which rapidly progressed in size. Five patients died within 6 months, one within 1 year after progression despite treatment. Six of the seven patients also had multiple other liver nodules on initial MRI; those that showed ring enhancement rapidly progressed but those without, did not show rapid progression.
CONCLUSION:
Patients with rapidly progressive HCC had underlying hepatitis C and intense ring enhancement on initial MRI. This group of patients should be evaluated further to determine if they might benefit from early intervention.

Richter Transformation of Chronic Lymphocytic Leukemia: A Review of Fluorodeoxyglucose Positron Emission Tomography–Computed Tomography and Molecular Diagnostics

Copyright © 2017 © 2017, Shaikh et al.
Cureus. 2017 Jan;9(1) doi: 10.7759/cureus.968

Abstract

BACKGROUND:
Chronic lymphocytic leukemia (CLL) is a low-grade B-cell proliferative disease with a generally indolent course. In a few cases, it undergoes transformation and becomes a more aggressive malignancy, such as diffuse large B-cell lymphoma (DLBCL). This process, which is called Richter transformation (RT), is often detected too late and is associated with a poor prognosis. There are multiple molecular diagnostic approaches to detect RT in preexisting CLL. Metabolic imaging using 18-fluorine fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET/CT) can be a very useful tool for early detection of RT and which can hence allow for timely intervention, thereby improving the patient’s chances of survival.

Technical Challenges in the Clinical Application of Radiomics

Radiomics is a quantitative approach to medical image analysis targeted at deciphering the morphologic and functional features of a lesion. Radiomic methods can be applied across various malignant conditions to identify tumor phenotype characteristics in the images that correlate with their likelihood of survival, as well as their association with the underlying biology. Identifying this set of characteristic features, called tumor signature, holds tremendous value in predicting the behavior and progression of cancer, which in turn has the potential to predict its response to various therapeutic options. We discuss the technical challenges encountered in the application of radiomics, in terms of methodology, workflow integration, and user experience, that need to be addressed to harness its true potential.

Voxel-wise correlation of PET/CT with multiparametric MRI and histology of the prostate using a sophisticated registration framework.

OBJECTIVES:

To develop a registration framework for correlating positron emission tomography/computed tomography (PET/CT) images with multiparametric MRI (mpMRI) and histology of the prostate, thereby enabling voxel-wise analysis of imaging parameters.

PATIENTS AND METHODS:

In this prospective proof-of-concept study, nine patients scheduled for radical prostatectomy underwent mpMRI and PET/CT imaging prior to surgery. One had PET imaging using 18 F-fluoromethylcholine (FCH), five using 68 Ga-labelled prostate-specific membrane antigen (PSMA)-HBED-CC (PMSA-11) and three using a trial 68 Ga-labelled THP-PSMA tracer. PET/CT data was co-registered with mpMRI via the CT scan and an in vivo 3D T2w MRI, and then co-registered with ground truth histology data using ex vivo MRI of the prostate specimen. Maximum and mean standardised uptake values (SUVmax and SUVmean) were extracted from PET data using tumour annotations from histology, and Kolmogorov-Smirnov tests were carried out to compare between tumour and benign voxel values. Correlation analysis was performed between mpMRI and PET SUV tumour voxels using Pearson’s correlation coefficient and R squared statistics.

RESULTS:

PET/CT data from all nine patients were successfully registered with mpMRI and histology data. SUVmax and SUVmean ranged from 2.21 to 12.11 and 1.08 to 4.21, respectively. All patients showed the PET SUV values in benign and tumour voxels were from statistically different distributions. Correlation analysis showed no consistent trend between the T2w or ADC values and PET SUV. However, parameters from DCE MRI including the maximum enhancement (ME), volume transfer constant Ktrans and the initial area under the contrast agent concentration curve (iAUGC60) showed consistent positive correlations with PET SUV. Furthermore, R2* values from BOLD MRI showed consistent negative correlations with PET SUV voxel values.

CONCLUSION:

We have developed a novel framework for registering and correlating PET/CT data at a voxel-level with mpMRI and histology. Despite registration uncertainties, perfusion and oxygenation parameters from DCE MRI and BOLD imaging showed correlations with PET SUV. Further analysis will be performed on a larger patient cohort to quantify these proof-of-concept findings. Improved understanding of the correlation between mpMRI and PET will provide supportive information for focal therapy planning of the prostate.

Magnetic Resonance Imaging of Gallbladder and Biliary System

Gallbladder and biliary system pathologic component is a spectrum of benign and malignant conditions. Standard magnetic resonance imaging techniques when used together with magnetic resonance cholangiopancreatography (MRCP) can evaluate gallbladder and biliary system pathologic conditions. Inflammatory diseases are characterized by thickening and intense mucosal contrast enhancement of the affected bile ducts and or gallbladder wall. Postinflammatory changes can be appreciated on MRCP with short or long segment strictures of the bile ducts. Serial contrast-enhanced images show reactive inflammatory changes in the liver parenchyma. Neoplastic diseases of the gallbladder and the biliary tree are evaluated on T2-weighted fat-suppressed echo train and serial contrast-enhanced images and their obstructive effect can be displayed on MRCP images. In this paper, we will review the spectrum of MRI findings of gallbladder and biliary system pathologic conditions.

Sinonasal NUT-Midline Carcinoma – A Multimodality Approach to Diagnosis, Staging and Post-Surgical Restaging

Nuclear protein testis (NUT) midline carcinoma is a rare malignancy involving predominantly the midline structures of the body. It is characterized by its genotypic feature of BRD4-NUT translocation, which is in contrast with other malignant processes that are usually categorized based on their histologic/phenotypic features. As these tumors may vary in their histologic presentation, they can be misdiagnosed as poorly differentiated carcinomas. Moreover, they are often very aggressive and associated with high mortality. Therefore, it is extremely important to diagnose them early using computed tomography (CT) and magnetic resonance imaging (MRI) and perform staging and restaging using 18-fluorodeoxyglucose positron emission tomography/computed tomography (18-FDG PET/CT), in addition to accurately identifying them at a microscopic and molecular level. We report a unique case of a sinonasal NUT midline carcinoma that was diagnosed with CT, staged with PET/CT, and restaged using PET/CT and MRI.

18F-FDG PET/CT Imaging of Gallbladder Adenocarcinoma – A Pictorial Review

Gallbladder adenocarcinoma is an uncommon and serious disease. The primary disease grows rapidly with local invasion into the liver and with distant spread to lymph nodes. It is often detected late, due to which management can be challenging. Despite routine use of computed tomography (CT) and ultrasonography (US) for detection, magnetic resonance imaging (MRI) is often considered for a detailed assessment of the anatomic behavior of these tumors. We share three cases where 18-FDG PET/CT played a role in management thereof.

Diagnostic yield of FDG PET/CT, MRI, and CSF cytology in nonbiopsiable Neurolymphomatosis as a heralding feature of Diffuse B-cell Lymphoma recurrence.

Neurolymphomatosis (NL) is a rare condition associated with lymphomas in which various structures of the nervous system are infiltrated by malignant lymphocytes. Rarely, it may be the presenting feature of recurrence of lymphoma otherwise deemed to be in remission. It is crucial, as is the case with all types of nodal or visceral involvement of lymphoma, to identify the disease early and initiate treatment with chemotherapy and/or radiation therapy. Positron emission tomography-computed tomography (PET-CT) has been shown to be a sensitive modality for staging, restaging, biopsy guidance, therapy response assessment, and surveillance for recurrence of lymphoma. Magnetic resonance imaging (MRI) is another useful imaging modality, which, along with PET/CT, compliment cerebrospinal spinal fluid (CSF) cytology and electromyography (EMG) in the diagnosis of NL. Performing nerve biopsies to confirm neurolymphomatosis can be challenging and with associated morbidity. The case presented herein illustrates the practical usefulness of these tests in detecting NL as a heralding feature of lymphoma recurrence, especially in the absence of histopathologic correlation.