Noncontrast Magnetic Resonance Imaging Technique Research Articles

Temporal Changes in Cerebral Blood Flow during Migraine with Aura of Alternating Left and Right Homonymous Hemianopsia.

A 16-year-old boy presented with sudden left homonymous hemianopsia followed by right ocular and occipital pain. Arterial spin labeling (ASL), a non-contrast magnetic resonance imaging technique used to evaluate perfusion, showed a decrease in cerebral blood flow in the right occipital lobe. Three hours after admission, the patient experienced right homonymous hemianopsia and ocular-to-occipital pain on the contralateral side. ASL revealed a decreased cerebral blood flow in the left occipital lobe. We ultimately diagnosed the patient with first-time migraine with aura, in which cortical spreading depression was visualized as decreased cerebral blood flow using ASL.

Pilot study of contrast-free MRI reveals significantly impaired calf skeletal muscle perfusion in diabetes with incompressible peripheral arteries.

Patients with diabetes mellitus (DM) are more likely to have densely calcified lesions in the below-the-knee tibial arteries. However, the relationship between peripheral arterial calcification and local skeletal muscle perfusion has not been explored. Thirty subjects were prospectively recruited into three groups in this pilot study: (1) Non-DM: 10 people without DM; (2) DM, ABI < 1.3: 10 people with DM and normal ankle-brachial index (ABI) (0.9-1.3); and (3) DM, ABI ⩾ 1.3: 10 people with DM and ABI ⩾ 1.3. All subjects underwent calf perfusion measurements at rest and during an isometric plantarflexion contraction exercise within the magnetic resonance imaging (MRI) system. The noncontrast MRI techniques were applied to quantitatively assess skeletal muscle blood flow (SMBF) and oxygen extraction fraction (SMOEF) in medial gastrocnemius and soleus muscles. Both SMBF and SMOEF reserves were calculated as the ratio of the exercise value to the resting value. Exercise SMBF and SMOEF values in the medial gastrocnemius muscle were lower in the two DM groups than in the non-DM group (p < 0.05). The SMBF reserve in medial gastrocnemius was significantly lower in the DM, ABI ⩾ 1.3 group compared to the DM, ABI < 1.3 group (p < 0.05). This study demonstrates that people with DM and calcified arteries had lower perfusion in gastrocnemius muscle compared to those without DM and those with DM and a normal ABI.

Contrast-Enhanced Echocardiography Imaging With a Noncontrast MRI Technique Used in a Patient With Chronic Kidney Disease to Diagnose Loeffler Endocarditis

Loeffler endocarditis is rare and can initially be a clinically silent cardiac disorder. Given its natural history with evolving stages and its vague initial cardiac presentation, it is important to keep this as a differential diagnosis. Without treatment, this disorder is progressive and may lead to a possible restrictive cardiomyopathy-related heart failure. Here, a rare case who presented with nonspecific chest pain is reported, which was recognized early by a routine noninvasive transthoracic echocardiography (TTE) imaging study. This was followed by the addition of contrast enhancement techniques, which made it possible to solidify the diagnosis of the mass to a right ventricular thrombus (possibly secondary to the hypereosinophilia syndrome), with isolated right ventricular involvement. Magnetic resonance imaging (MRI) of the heart, without contrast, was performed to further analyze the anatomic location of this entity. A high index of suspicion for Loeffler endocarditis helped identify this condition.

SAT-292 MR IMAGING BIOMARKERS OF DIABETIC KIDNEY DISEASE

New drug development tools are needed for monitoring response to therapy in chronic kidney disease (CKD) with increased precision and repeatability. Magnetic resonance imaging (MRI) has great potential to non-invasively assess functional and morphologic changes in the kidney to improve patient selection and response monitoring in clinical trials for CKD. In this study, we have assessed multiple MRI variables in a diabetic nephropathy (DN) population. The study examined T2DM patients with an established diagnosis of DN and an eGFR between 15-60 ml/min/1.73 m2 as well as age- and gender-matched healthy controls. The analysis evaluated 20 CKD4 and 16 CKD3 patients and 20 healthy controls. Measured glomerular filtration rate (mGFR) was assessed using iohexol clearance. A wide range of non-contrast MRI techniques were assessed. MRI techniques included:R2* for assessment of renal hypoxiaApparent Diffusion Coefficient (ADC) as a potential measurement of renal fibrosisR1 for interstitial water balanceArterial Spin Labelling (ASL) for cortical perfusionRenal artery blood flow (peak systolic and end diastolic velocity, mean arterial flow, renal artery resistive index (RARI))Global perfusion (mean arterial flow/kidney volume)Kidney volume corrected for body surface area Tabled 1Healthy controlsCKD3CKD4correlation with mGFR (r2)p-value of correlationR2* cortex (s-1)17.3 (1.4)17.2 (1.6)17.0 (1.2)0.0060.59R2* medulla (s-1)26.0 (2.3)24.5 (3.7)22.8 (3.6)0.1240.008ADC cortex (mm2s-1 x 10-3)2.14 (0.24)1.96 (0.17)1.87 (0.32)0.1940.0007ADC medulla (mm2s-1 x 10-3)2.04 (0.27)1.86 (0.17)1.85 (0.23)0.1260.007R1 cortex (s-1)1.17 (0.10)1.02 (0.07)0.95 (0.12)0.493<0.0001R1 medulla (s-1)0.77 (0.05)0.78 (0.04)0.76 (0.07)0.0070.53ASL perfusion cortex (ml/100g/min)250 (61)144 (60)94 (51)0.519<0.0001Peak velocity max (cm/s)54.3 (8.3)59.8 (14.2)43.1 (11.1)0.1020.015Peak velocity min (cm/s)17.0 (3.9)11.3 (3.2)6.72 (2.45)0.618<0.0001RARI0.68 (0.06)0.81 (0.06)0.84 (0.06)0.576<0.0001Mean arterial flow (ml/s)9.43 (1.76)6.39 (1.46)4.30 (1.28)0.725<0.0001PC Perfusion (ml/100g/min)458 (54)339 (54)266 (86)0.616<0.0001Kidney volume/BSA (ml)63.0 (7.4)56.7 (14.8)49.9 (11.0)0.1790.0009 Open table in a new tab Several of the measured MRI variables correlate strongly with mGFR, indicating that these biomarkers are biologically relevant while providing additional information on pathophysiology. Given the known relationship between MRI biomarkers and mGFR plus the intra-subject CoV, the number of subjects needed to detect, for example, a 2 ml/min/1.73m2change in mGFR can be calculated.

MRI in Menière’s Disease

The visualization of the morphologic substrate of Meniere’s disease -the endolymphatic hydrops – can be performed using non-contrast as well as contrast-enhanced magnetic resonance imaging techniques. The non-contrast magnetic resonance imaging technique uses a heavily T2-weighted sequence; however, the reproducibility of this technique remains to be confirmed. The contrast-enhanced techniques most frequently use a 3-dimensional fluid-attenuated inversion recovery sequence or a real 3-dimensional inversion recovery sequence either after intratympanic gadolinium administration either 4 hours after intravenous gadolinium administration. The latter is the most frequently used technique and is able to detect definite Meniere’s disease with a high sensitivity and specificity. It has been proven to be a reliable technique with a high diagnostic accuracy, enabling the visualization of endolymphatic hydrops.

Non-contrast magnetic resonance imaging for bladder cancer: fused high b value diffusion-weighted imaging and T2-weighted imaging helps evaluate depth of invasion.

To investigate the utility of fused high b value diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI) for evaluating depth of invasion in bladder cancer. We included 62 patients with magnetic resonance imaging (MRI) and surgically confirmed urothelial carcinoma in the urinary bladder. An experienced genitourinary radiologist analysed the depth of invasion (T stage <2 or ≥2) using T2WI, DWI, T2WI plus DWI, and fused DWI and T2WI (fusion MRI). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were investigated. Area under the curve (AUC) was analysed to identify T stage ≥2. The rate of patients with surgically confirmed T stage ≥2 was 41.9% (26/62). Sensitivity, specificity, PPV, NPV and accuracy were 50.0%, 55.6%, 44.8%, 60.6% and 53.2%, respectively, with T2WI; 57.7%, 77.8%, 65.2%, 71.8% and 69.4%, respectively, with DWI; 65.4%, 80.6%, 70.8%, 76.3% and 74.2%, respectively, with T2WI plus DWI and 80.8%, 77.8%, 72.4%, 84.9% and 79.0%, respectively, with fusion MRI. AUC was 0.528 with T2WI, 0.677 with DWI, 0.730 with T2WI plus DWI and 0.793 with fusion MRI for T stage ≥2. Fused high b value DWI and T2WI may be a promising non-contrast MRI technique for assessing depth of invasion in bladder cancer. • Accuracy of fusion MRI was 79.0% for T stage ≥2 in bladder cancer. • AUC of fusion MRI was 0.793 for T stage ≥2 in bladder cancer. • Diagnostic performance of fusion MRI was comparable with T2WI plus DWI. • As a non-contrast MRI technique, fusion MRI is useful for bladder cancer.

Feasibility of detecting pulmonary embolism using noncontrast MRI.

Purpose. The purpose of this study was to evaluate the feasibility of detecting pulmonary emboli utilizing noncontrast magnetic resonance imaging techniques in patients with known pulmonary embolism. Materials and Methods. Eleven patients were enrolled in a study to evaluate right ventricular function by cardiac MRI in patients diagnosed with acute pulmonary embolism on CT pulmonary angiogram. Cardiac MRI was performed as soon as possible following pulmonary embolism detection. Two independent observers reviewed the precontrast portion of each MRI, scoring right, left, and lobar arteries as positive or negative for PE. The CTs were reviewed and interpreted in the same manner. Results. MRI was obtained on average of 40 hours after the CT. Forty-eight vessels were affected by PE on CT, 69% of which were identified on MRI. All eight pulmonary emboli located in the right or left pulmonary arteries were detected on MRI. Of the 15 pulmonary emboli that were not detected on MRI, 7 were subsegmental, 6 were segmental, and 2 were located in a branch not included in the MRI field of view. Conclusions. Most pulmonary emboli detected on CT were identified on noncontrast MRI, even though our MRI protocol was not optimized for pulmonary artery visualization.

Feasibility study of myocardial perfusion and oxygenation by noncontrast MRI: comparison with PET study in a canine model

The purpose of this study was to examine the feasibility of quantifying myocardial blood flow (MBF) and rate of myocardial oxygen consumption (MVO(2)) during pharmacologically induced stress without using a contrast agent. The former was measured by the arterial spin labeling (ASL) method and the latter was obtained by measuring the oxygen extraction fraction (OEF) with the magnetic resonance imaging (MRI) blood oxygenation level-dependent effect and Fick's law. The MRI results were compared with the established positron emission tomography (PET) methods. Six mongrel dogs with induced acute moderate left coronary artery stenosis were scanned using a clinical PET and a 1.5-T MRI system, in the same day. Regional MBF, myocardial OEF and MVO(2) were measured with both imaging modalities. Correlation coefficients (R(2)) of the three myocardial indexes (MBF, OEF and MVO(2)) between MRI and PET methods ranged from 0.70 to 0.93. Bland-Altman statistics demonstrated that the estimated precision of the limits of agreement between MRI and PET measurements varied from 18% (OEF) to 37% (MBF) and 45% (MVO(2)). The detected changes in these indexes, at rest and during dobutamine stress, were similar between two image modalities. The proposed noncontrast MRI technique is a promising method to quantitatively assess myocardial perfusion and oxygenation.

NONCONTRAST DYNAMIC MAGNETIC RESONANCE IMAGING FOR QUANTITATIVE ASSESSMENT OF FEMALE SEXUAL AROUSAL

We evaluated a noncontrast, dynamic magnetic resonance imaging (MRI) technique for quantitative evaluation of the female sexual arousal response and compared these results with those of a previously described, contrast enhanced MRI technique. Eight normal, healthy volunteer women underwent 2 separate MRI sessions, during which they were shown audiovisual material consisting of interleaved neutral and audiovisual sexual stimulation segments. Serial high resolution MRI of the genital structures was done at 3-minute intervals during a 45-minute period. Images were analyzed in blinded fashion and measurements of clitoral volume with time were obtained for each subject. Measured clitoral volumes together with the percent change in clitoral volume during audiovisual sexual stimulation for MRI sessions 1 and 2 were compared within subjects. Results were also compared to those of prior contrast enhanced MRI studies in the same subjects. There was excellent intrasubject reproducibility between sessions 1 and 2 using the noncontrast MRI technique (r = 0.99). There was also excellent agreement between the current noncontrast study and prior contrast enhanced studies with a correlation coefficient of 0.89. Dynamic, noncontrast MRI of the female genitalia appears to be a reproducible, nonintrusive and objective way to assess quantitatively the sexual arousal response in women without sexual difficulties.