Revealing tumor microstructure with oscillating diffusion encoding MRI in pre-surgical and post-treatment glioma patients.

PURPOSE: We hypothesized that the time-dependent diffusivity at short diffusion times, as measured by oscillating gradient spin echo (OGSE) diffusion MRI, can characterize tissue microstructures in glioma patients. THEORY AND METHODS: Five adult patients with known diffuse glioma, including two pre-surgical and three with new enhancing lesions after treatment for high-grade glioma, were scanned in an ultra-high-performance gradient 3.0T MRI system. OGSE diffusion MRI at 30-100 Hz and pulsed gradient spin echo diffusion imaging (approximated as 0 Hz) were obtained. The ADC and trace-diffusion-weighted image at each acquired frequency were calculated, that is, ADC (f) and TraceDWI (f). RESULTS: In pre-surgical patients, biopsy-confirmed solid enhancing tumor in a high-grade glioblastoma showed higher ADC ( f ) ADC ( 0 Hz ) $$ \frac{\mathrm{ADC}\ (f)}{\mathrm{ADC}\ \left(0\ \mathrm{Hz}\right)} $$ and lower TraceDWI ( f ) TraceDWI ( 0 Hz ) $$ \frac{\mathrm{TraceDWI}\ (f)}{\mathrm{TraceDWI}\ \left(0\ \mathrm{Hz}\right)} $$ , compared to that at same OGSE frequency in a low-grade astrocytoma. In post-treatment patients, the enhancing lesions of two patients who were diagnosed with tumor progression contained more voxels with high ADC ( f ) ADC ( 0 Hz ) $$ \frac{\mathrm{ADC}\ (f)}{\mathrm{ADC}\ \left(0\ \mathrm{Hz}\right)} $$ and low TraceDWI ( f ) TraceDWI ( 0 Hz ) $$ \frac{\mathrm{TraceDWI}\left(\mathrm{f}\right)}{\mathrm{TraceDWI}\left(0\ \mathrm{Hz}\right)} $$ , compared to the enhancing lesions of a patient who was diagnosed with treatment effect. Non-enhancing T2 signal abnormality lesions in both the pre-surgical high-grade glioblastoma and post-treatment tumor progressions showed regions with high ADC ( f ) ADC ( 0 Hz ) $$ \frac{\mathrm{ADC}\ (f)}{\mathrm{ADC}\ \left(0\ \mathrm{Hz}\right)} $$ and low TraceDWI ( f ) TraceDWI ( 0 Hz ) $$ \frac{\mathrm{TraceDWI}\ \left(\mathrm{f}\right)}{\mathrm{TraceDWI}\ \left(0\ \mathrm{Hz}\right)} $$ , consistent with infiltrative tumor. The solid tumor of the glioblastoma, the enhancing lesions of post-treatment tumor progressions, and the suspected infiltrative tumors showed high diffusion time-dependency from 30 to 100 Hz, consistent with high intra-tumoral volume fraction (cellular density). CONCLUSION: Different characteristics of OGSE-based time-dependent diffusivity can reveal heterogenous tissue microstructures that indicate cellular density in glioma patients.

ACR Appropriateness Criteria® Chronic Chest Pain-High Probability of Coronary Artery Disease.

In patients with chronic chest pain in the setting of high probability of coronary artery disease (CAD), imaging has major and diverse roles. First, imaging is valuable in determining and documenting the presence, extent, and severity of myocardial ischemia, hibernation, scarring, and/or the presence, site, and severity of obstructive coronary lesions. Second, imaging findings are important in determining the course of management of patients with suspected chronic myocardial ischemia and better defining those patients best suited for medical therapy, angioplasty/stenting, or surgery. Third, imaging is also necessary to determine the long-term prognosis and likely benefit from various therapeutic options by evaluating ventricular function, diastolic relaxation, and end-systolic volume. Imaging studies are also required to demonstrate other abnormalities, such as congenital/acquired coronary anomalies and severe left ventricular hypertrophy, that can produce angina in the absence of symptomatic coronary obstructive disease due to atherosclerosis. Clinical risk assessment is necessary to determine the pretest probability of CAD. Multiple methods are available to categorize patients as low, medium, or high risk for developing CAD. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Medical 3D Printing for the Radiologist.

While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article.

ACR Appropriateness Criteria® chronic chest pain--high probability of coronary artery disease.

Imaging is valuable in determining the presence, extent, and severity of myocardial ischemia and the severity of obstructive coronary lesions in patients with chronic chest pain in the setting of high probability of coronary artery disease. Imaging is critical for defining patients best suited for medical therapy or intervention, and findings can be used to predict long-term prognosis and the likely benefit from various therapeutic options. Chest radiography, radionuclide single photon-emission CT, radionuclide ventriculography, and conventional coronary angiography are the imaging modalities historically used in evaluating suspected chronic myocardial ischemia. Stress echocardiography, PET, cardiac MRI, and multidetector cardiac CT have all been more recently shown to be valuable in the evaluation of ischemic heart disease. Other imaging techniques may be helpful in those patients who do not present with signs classic for angina pectoris or in those patients who do not respond as expected to standard management. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Computerized information management for institutional review boards.

The use of human subjects for medical research in most industrialized nations requires the scientific and ethical scrutiny of research proposals by a governing institutional review board (IRB) or its equivalent. As part of their primary charge to protect human subjects, IRBs are responsible for the regulatory oversight of not only the research protocol itself but also the research conduct of the investigators and, if applicable, the funding sponsor. This article will discuss the regulatory requirements for an accurate account of IRB protocols and investigators and present an overview of the general flow of information for an IRB protocol. The current and potential uses of information management systems by IRBs will also be reviewed and accompanied by a discussion of the potential advantages and disadvantages of various computerized information systems for management of clinical research.

Association between fetal lymphedema and congenital cardiovascular defects in Turner syndrome.

OBJECTIVES: Turner syndrome (TS) is associated with congenital cardiovascular defects (CCVDs), most commonly bicuspid aortic valve (BAV) and aortic coarctation (COARC), congenital renal anomalies, and fetal lymphedema. It has been theorized that compressive or obstructive effects of fetal lymphedema may actually cause cardiovascular and renal dysmorphogenesis in TS. The objective of this study was to determine whether there is a specific association between a history of fetal lymphedema and CCVDs in monosomy X, or TS, independent of karyotype or general severity of the phenotype. METHODS: This was a prospective study of 134 girls and women who have TS (mean age: 30 years) and were clinically evaluated for evidence of fetal lymphedema, classified as central (signified by the presence of neck webbing) or peripheral (current or perinatal, or dysplastic fingernails). The presence of BAV and/or COARC was detected by magnetic resonance imaging combined with echocardiography, and renal anomalies were determined by ultrasound. RESULTS: There is a strong association between developmental central lymphedema, signified by neck webbing, and the presence of BAV (chi2 = 10) and COARC (chi2 = 8). The association between webbed neck and CCVDs was independent of karyotype. There was, in contrast, no significant association between renal anomalies and webbed neck or CCVDs. CONCLUSIONS: The strong, statistically significant association between neck webbing and the presence of BAV and COARC in TS suggests a pathogenetic connection between fetal lymphatic obstruction and defective aortic development. The presence of neck webbing in TS should alert the clinician to the possibility of congenital cardiovascular defects.

MR evaluation of solid renal masses.

After diagnosis of a suspicious renal mass on ultrasound or CT, renal MR imaging typically is ordered to characterize the mass further, stage the mass, or resolve discordant ultrasound and CT results. MR imaging may also be ordered in cases in which ultrasound is poor or in instances in which contrast-enhanced CT may be ill advised.

Renal masses: quantitative assessment of enhancement with dynamic MR imaging.

PURPOSE: To establish a quantitative magnetic resonance (MR) imaging contrast enhancement criterion for distinguishing cysts from solid renal lesions. MATERIALS AND METHODS: Regions of interest were measured in 74 patients with renal lesions evaluated by means of dynamic contrast material-enhanced MR imaging with serial breath-hold spoiled gradient-echo acquisitions. Sensitivity for renal tumors and specificity for renal cysts were established by using percentage of enhancement thresholds that varied between 5% and 35%. RESULTS: The mean percentage of enhancement at MR imaging for the 50 renal cysts was less than 5%; for the 50 renal tumors, it was 97% or higher. With use of a threshold percentage of enhancement of 15% and results obtained between 2 and 4 minutes after administration of contrast material, all malignancies (sensitivity for tumor, 100%) were diagnosed, and there were 6% or fewer false-positive tumor diagnoses. Lower thresholds resulted in unacceptably high false-positive rates (ie, cysts that appeared to enhance-pseudoenhancement), whereas higher threshold values (>20%) resulted in an unacceptably lower sensitivity for tumors. CONCLUSION: The optimal percentage of enhancement threshold for distinguishing cysts from malignancies with the imaging technique prescribed was 15%, and the optimal timing for measurement was 2-4 minutes after administration of contrast material.