Renal blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) is a noninvasive fast technique to characterize renal function. Here we evaluated the impact of renal function on the relaxation rate (R2(*)) in the cortex and medulla to provide baseline data for further use of renal BOLD-MRI. This parameter was evaluated in 400 patients scheduled for abdominal imaging who underwent transversal blood oxygen level-dependent measurements with a multi-echo gradient-echo sequence with 12 echo times. The loss of phase coherence (T2(*)) maps were generated in which kidney regions of interest were selected to differentiate the medulla and cortex, and R2(*) was equated to 1/T2(*). Individual R2(*) values were, in turn, correlated to the eGFR (MDRD formula of 280 patients with available serum creatinine measurements), age, and gender each for 1.5 and 3.0 T field-strength scans of 342 patients. At both the field strengths, no significant differences in R2(*) of the cortex and medulla were found between patient gender, age, eGFR, or between different stages of chronic kidney disease determined using the KDOQI system. Thus, BOLD-MRI of a non-specific patient population failed to discriminate between the patients with various stages of chronic kidney disease.

As clinical magnetic resonance (MR) imaging becomes more versatile and more complex, it is increasingly difficult to develop and maintain a thorough understanding of the physical principles that govern the changing technology. This is particularly true for practicing radiologists, whose primary obligation is to interpret clinical images and not necessarily to understand complex equations describing the underlying physics. Nevertheless, the physics of MR imaging plays an important role in clinical practice because it determines image quality, and suboptimal image quality may hinder accurate diagnosis. This article provides an image-based explanation of the physics underlying common MR imaging artifacts, offering simple solutions for remedying each type of artifact. Solutions that have emerged from recent technologic advances with which radiologists may not yet be familiar are described in detail. Types of artifacts discussed include those resulting from voluntary and involuntary patient motion, magnetic susceptibility, magnetic field inhomogeneities, gradient nonlinearity, standing waves, aliasing, chemical shift, and signal truncation. With an improved awareness and understanding of these artifacts, radiologists will be better able to modify MR imaging protocols so as to optimize clinical image quality, allowing greater confidence in diagnosis.

Using parallel imaging, DTI measurements of the kidneys are feasible within a single breath-hold with good discrimination between cortex and medulla. Parallel imaging allows more slices and a superior resolution. DTI measurements of the kidney allows visualization of medullary flow, in pathology ADC and FA were altered. Further investigations will be required to evaluate the role of DTI for studying and monitoring renal ultrastructure.

If an adequate amount of gadodiamide and fast MR sequences are used, quantification of pulmonary blood flow and volume is feasible.

The combination of fast MR perfusion imaging and high-spatial-resolution MR angiography with parallel acquisition techniques enables the differentiation of PPH from CTEPH with high accuracy.

computed tomography (ct) and magnetic resonance imaging (MRi) can quantify muscle mass and quality. However, it is still unclear if ct and MRi derived measurements can be used interchangeable. In this prospective study, fifty consecutive participants of a cancer screening program underwent same day low-dose chest ct and MRi. cross-sectional areas (cSA) of the paraspinal skeletal muscles were obtained. CT and MRI muscle fat infiltration (MFI) were assessed by mean radiodensity in Hounsfield units (HU) and proton density fat fraction (MRi pDff), respectively. cSA and Mfi were highly correlated between CT and MRI (CSA: r = 0.93, P < 0.001; MFI: r = − 0.90, P < 0.001). Mean CSA was higher in CT compared to MRI (46.6cm 2 versus 43.0cm 2 ; P = 0.05) without significance. Based on MRI pDff , a linear regression model was established to directly estimate skeletal muscle fat content from ct. Bland-Altman plots showed a difference between measurements of − 0.5 cm 2 to 7.6 cm 2 and − 4.2% to 2.4% regarding measurements of cSA and Mfi, respectively. in conclusion, the provided results indicate interchangeability of ct and MRi derived imaging biomarkers of skeletal muscle quantity and quality. comparable to MRi pDff , skeletal muscle fat content can be quantified from CT, which might have an impact of analyses in larger cohort studies, particularly in sarcopenia patients. Decrease in skeletal muscle quantity and quality, commonly termed sarcopenia, is known as a strong risk factor for adverse outcomes in several chronic and malignant diseases. Sarcopenia was shown to have high socioeconomic and personal burden and leads to impaired activity in daily life, decreased mobility, loss of independency and a higher mortality 1-3. Initially, sarcopenia was considered to be an age-related phenomenon 4. However, it is now increasingly realized that sarcopenia may also occur in younger patients, for example secondary due to systemic diseases. Moreover, it was realized that sarcopenia may not be captured by conventional anthropometric measurements such as body mass index (BMI) or waist-to-hip-ratio, particularly in obese patients 1,5. Amount and quality of skeletal muscles can be assessed by cross-sectional imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Previous studies indicate that both modalities may provide imaging based quantitative biomarkers of sarcopenia, and that these biomarkers may reveal prognostic information in various severe diseases 6-10. Thereby, cross sectional areas (CSA) of skeletal muscles at distinct anatomical landmarks were shown to provide accurate surrogates of total skeletal muscle amount and therefore may be used to identify patients with low muscle mass 1,6,7. The most common approaches to estimate skeletal muscle amount are determination of circumferential skeletal muscle area or psoas muscle area, both typically obtained at lumbar vertebral levels 1. However, these landmarks are frequently not captured in several imaging protocols, although sarcopenia is known to b...

A combined MR angiographic approach in which a low total gadolinium dose (0.1 mmol/kg) is used yields excellent image quality and is accurate in the diagnosis of peripheral arterial stenosis.

The current outbreak of coronavirus SARS-CoV-2 has reached multiple countries worldwide. While the number of newly diagnosed cases and fatalities is rising quickly, far-reaching measures were enacted to prevent further spread. Diagnosis relies on clinical presentation, exposure history, PCR using specimens from the respiratory tract together with computed tomography (CT) imaging. One of the hallmarks of a critical course of COVID-19 is the development of severe acute respiratory distress syndrome (ARDS). As management of COVID-19 can be considered a multi-disciplinary approach involving various medical specialties, we here review the first 18F-FDG-PET/CT scans of COVID-19 to discuss how Nuclear Medicine could contribute to management of this disease.