Imaging Considerations

Imaging in Rheumatoid Arthritis: The Role of Magnetic Resonance Imaging and Computed Tomography.

Abstract

In suspected and diagnosed rheumatoid arthritis (RA), magnetic resonance imaging (MRI) allows detection of all relevant pathologies, such as synovitis, tenosynovitis, bone marrow edema (osteitis), bone erosion and cartilage damage. MRI is more sensitive than clinical examination for monitoring disease activity (i.e., inflammation) and more sensitive than conventional radiography and ultrasonography for monitoring joint destruction. In suspected RA, MRI bone marrow edema predicts development of RA, and in early RA patients, it predicts subsequent structural damage progression. CT is the standard reference imaging modality for visualizing bone damage, including bone erosions in RA, but lacks sensitivity for soft-tissue changes, including synovitis and tenosynovitis. CT has a minimal role in RA clinical trials and practice, except in selected patients where MRI is contraindicated or not available or if crystal arthritis such as gout or pseudo-gout is suspected. MRI has documented utility in diagnosis, monitoring and prognostication of patients with RA and is increasingly used for these purposes in clinical practice and particularly clinical trials.

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.

RSNA Diagnosis Live: A Novel Web-based Audience Response Tool to Promote Evidence-based Learning.

Audience response systems have become more commonplace in radiology residency programs in the last 10 years, as a means to engage learners and promote improved learning and retention. A variety of systems are currently in use. RSNA Diagnosis Live™ provides unique features that are innovative, particularly for radiology resident education. One specific example is the ability to annotate questions with subspecialty tags, which allows resident performance to be tracked over time. In addition, deficiencies in learning can be monitored for each trainee and analytics can be provided, allowing documentation of resident performance improvement. Finally, automated feedback is given not only to the instructor, but also to the trainee. Online supplemental material is available for this article.

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.

Translational Radiomics: Defining the Strategy Pipeline and Considerations for Application-Part II: From Clinical implementation to Enterprise.

Enterprise imaging has channeled various technological innovations to the field of clinical radiology, ranging from advanced imaging equipment and postacquisition iterative reconstruction tools to image analysis and computer-aided detection tools. More recently, the advancements in the field of quantitative image analysis coupled with machine learning-based data analytics, classification, and integration have ushered us into the era of radiomics, which has tremendous potential in clinical decision support as well as drug discovery. There are important issues to consider to incorporate radiomics as a clinically applicable system and a commercially viable solution. In this two-part series, we offer insights into the development of the translational pipeline for radiomics from methodology to clinical implementation (Part 1) and from that to enterprise development (Part 2)

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.

MRI findings of posttraumatic intrahepatic vascular shunts.

Purpose

To describe the features of posttraumatic intrahepatic vascular shunts (PIVS) as seen on MRI.

Materials and Methods

A search was performed for patients with MRI features compatible with PIVS in the Abdominal MRI databases between January 2002 and March 2008. This study was approved by our institutional review board. All patients were imaged using a protocol that included noncontrast T1‐weighted and T2‐weighted images, and postgadolinium gradient‐echo images.

Results

Eleven patients (eight men, three women; mean age 55.36 years; range 43–77 years) were identified with PIVS. The following imaging features were observed: dilation of afferent and efferent vessels (five patients), transient hepatic parenchymal blush in a watershed distribution (11 patients), and early opacification of efferent vessels (11 patients).

Conclusion

Patients with PIVS exhibit features that are distinctive for this entity and include: dilatation of efferent and afferent vessels, transient parenchymal blush, and early opacification of efferent vessels.

MR Imaging: Sequences we use and why.

Typically there are at least 8 different sets of images in a body magnetic resonance imaging (MRI) study, which can bewilder the radiologist who may be comfortable with looking at only 1 set of images required by computed tomography (CT). The standard MR sequences obtained are: noncontrast T1-weighted (T1W) in-phase, out-of-phase and fat-suppressed images, and T2-weighted (T2W) fat- and non-fat-suppressed images. Other standard sequences include contrast-enhanced T1W sequences imaged during the hepatic arterial dominant phase, early hepatic venous phase and the interstitial phase (Figure 1). This review describes the core data interpretation from these different imaging sets to raise the comfort level for image interpretation of abdominal MRI studies.