Acute cervicitis resembling gastric-type mucinous adenocarcinoma that was definitively diagnosed by cervical conization: A case report

Although imaging studies are not typically performed for clinical diagnosis of cervicitis, in this case magnetic resonance imaging (MRI) was performed because a lesion with a tumor-like gross appearance was found in the uterine cervix. We present a case of cervicitis in which clinical, imaging and pathological features overlapped with those of gastric-type mucinous adenocarcinoma (GAS). The patient, a 30-year-old woman, was referred to a gynecologist with a complaint of watery vaginal discharge. On visual examination, the uterine cervix was irregularly enlarged and bled easily, suggesting cervical cancer. The next day, the patient had a fever of 39°C and blisters appeared on her vulva due to herpes simplex virus type II infection. MRI showed a diffusely enlarged cervix with poorly marginated high signal intensity on T2-weighted imaging (WI) and apparent diffusion coefficient map as well as strong enhancement on contrast-enhanced T1WI, which are findings consistent with GAS. Although a punch biopsy showed only mild atypia of the cervical glands, this was not enough to completely rule out GAS. Consequently, laser conization of the lesion was performed for definitive diagnosis, and the diagnosis of cervicitis was made. Acute cervicitis can be difficult to differentiate from GAS based on symptoms, results of cervical biopsy and MR imaging because of their overlapping features. Even when a patient presents with a lesion with tumor-like gross appearance, acute cervicitis should be included in the differential diagnosis if the result of cervical biopsy is negative, especially when accompanied by infection-like fever.

Impaired oxygen extraction and adaptation of intracellular energy metabolism in cerebral small vessel disease

BACKGROUND

We aimed to investigate whether combined phosphorous (³¹P) magnetic resonance spectroscopic imaging (MRSI) and quantitative T 2 ' mapping are able to detect alterations of the cerebral oxygen extraction fraction (OEF) and intracellular pH (pH_i) as markers the of cellular energy metabolism in cerebral small vessel disease (SVD).

MATERIALS AND METHODS

32 patients with SVD and 17 age-matched healthy control subjects were examined with 3-dimensional ³¹P MRSI and oxygenation-sensitive quantitative T 2 ' mapping (1/ T 2 '  = 1/T₂* - 1/T₂) at 3 Tesla (T). PH_i was measured within the white matter hyperintensities (WMH) in SVD patients. Quantitative T 2 ' values were averaged across the entire white matter (WM). Furthermore, T 2 ' values were extracted from normal-appearing WM (NAWM) and the WMH and compared between patients and controls.

RESULTS

Quantitative T 2 ' values were significantly increased across the entire WM and in the NAWM in patients compared to control subjects (149.51 ± 16.94 vs. 138.19 ± 12.66 ms and 147.45 ± 18.14 vs. 137.99 ± 12.19 ms, p < 0.05). WM T 2 ' values correlated significantly with the WMH load (ρ=0.441, p = 0.006). Increased T 2 ' was significantly associated with more alkaline pH_i (ρ=0.299, p < 0.05). Both T 2 ' and pH_i were significantly positively correlated with vascular pulsatility in the distal carotid arteries (ρ=0.596, p = 0.001 and ρ=0.452, p = 0.016).

CONCLUSIONS

This exploratory study found evidence of impaired cerebral OEF in SVD, which is associated with intracellular alkalosis as an adaptive mechanism. The employed techniques provide new insights into the pathophysiology of SVD with regard to disease-related consequences on the cellular metabolic state.

Evaluation of in vivo MRI for detecting midodrine-induced arteritis in rats

There are no specific and sensitive biomarkers for arteritis, and the occurrence of arteritis in nonclinical toxicological studies of a candidate drug makes development of the drug very difficult. However, we showed in a previous study that the high signal intensity region around the artery on magnetic resonance imaging (MRI) could be a candidate biomarker for detection of arteritis. The present study was conducted to clarify the details of midodrine hydrochloride (MH)-induced arteritis lesions and whether arteritis induced by a mechanism other than the vasodilatory effect, which was evaluated in a previous study, could be detected by MRI. MH is a selective peripherally acting alpha-1 adrenergic receptor agonist, known to induce arteritis due to its vasoconstrictor action, but there is not enough information about MH-induced arteritis. Based on the data obtained under multiple dosing conditions, MH was administered subcutaneously to each rat once daily for 2 days at a dose level of 40 mg/kg/day for MRI assessment. The mesenteric arteries were examined using in vivo MRI at 1 day or 7 days after administration of the final dose and examined histopathologically. On the day after the final dose, high signal intensity region around the artery was observed in animals with minimal perivascular lesions confirmed by histopathology and not observed in an animal without histological changes. On the 7th day after the final dose, no abnormality was observed in histopathological examinations and no high signal intensity regions were observed by MRI in any animal. In conclusion, although further investigation is needed to confirm that high signal intensity is a reliable biomarker for humans, it is suggested that high signal intensity around the artery could be a versatile candidate biomarker with high specificity and sensitivity.

Effects of transcranial direct current stimulation on neural activity and functional connectivity during fear extinction

Background/Objective

Anxiety disorders are highly prevalent and negatively impact daily functioning and quality of life. Transcranial direct current stimulation (tDCS) targeting the dorsolateral prefrontal cortex (dlPFC), especially in the right hemisphere impacts extinction learning; however, the underlying neural mechanisms are elusive. Therefore, we aimed to investigate the effects of cathodal tDCS stimulation to the right dlPFC on neural activity and connectivity patterns during delayed fear extinction in healthy participants.

Methods

We conducted a two-day fear conditioning and extinction procedure. On the first day, we collected fear-related self-reports, clinical questionnaires, and skin conductance responses during fear acquisition. On the second day, participants in the tDCS group (n = 16) received 20-min offline tDCS before fMRI and then completed the fear extinction session during fMRI. Participants in the control group (n = 18) skipped tDCS and directly underwent fMRI to complete the fear extinction procedure. Whole-brain searchlight classification and resting-state functional connectivity analyses were performed.

Results

Whole-brain searchlight classification during fear extinction showed higher classification accuracy of threat and safe cues in the left anterior dorsal and ventral insulae and hippocampus in the tDCS group than in the control group. Functional connectivity derived from the insula with the dlPFC, ventromedial prefrontal cortex, and inferior parietal lobule was increased after tDCS.

Conclusion

tDCS over the right dlPFC may function as a primer for information exchange among distally connected areas, thereby increasing stimulus discrimination. The current study did not include a sham group, and one participant of the control group was not randomized. Therefore, to address potential allocation bias, findings should be confirmed in the future with a fully randomized and sham controlled study.

Primary synovial sarcoma of the shoulder: Case report of the "triple sign" on proton density magnetic resonance imaging

The first case of synovial sarcoma was published in 1893. The disease is a type of primary malignancy of the soft tissues. It is a rare and aggressive neoplasm of unknown tissue origin, characterized by strong metastatic potential and poor prognosis. The present case of a 64-year-old male patient with pain and swelling in his right shoulder and progressive loss of movement demonstrates an uncommon location for the neoplasm. Magnetic resonance proton-density fat-suppressed turbo spin-echo sequences show a heterogeneous mass in the right shoulder. The lack of homogeneity in the signal has been described in medical literature as the "triple sign" and is represented by low, intermediate, and high signal intensity areas through the neoplasm. Visible serpentine vessels spread through the tumor. There was a visible metastatic disease in the regional lymph nodes and metastatic foci in the adjacent bones. Pathological analysis of the tumor confirmed the diagnosis of biphasic synovial sarcoma. An oncological committee advised chemotherapy and radiotherapy. More prominent magnetic resonance imaging findings in synovial sarcoma that may facilitate the diagnostic process are the inhomogeneity and "triple sign" in proton density and T2 sequences, multilobulated tumors, septa, irregular borders, serpentine vascular channels, engagement of the adjacent bones and bone marrow, and involvement of the joint synovia.

Preliminary study of multiple b-value diffusion-weighted images and T1 post enhancement magnetic resonance imaging images fusion with Laplacian Re-decomposition (LRD) medical fusion algorithm for glioma grading

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LRD medical image fusion algorithm can be used for glioma grading.

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We can use the LRD fusion algorithm with MRI image for glioma grading.

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Fusing of DWI (b50) and T₁ enhancement (T₁Gd) by LRD, have highest diagnostic value for glioma grading.

Background

Grade of brain tumor is thought to be the most significant and crucial component in treatment management. Recent development in medical imaging techniques have led to the introduce non-invasive methods for brain tumor grading such as different magnetic resonance imaging (MRI) protocols. Combination of different MRI protocols with fusion algorithms for tumor grading is used to increase diagnostic improvement. This paper investigated the efficiency of the Laplacian Re-decomposition (LRD) fusion algorithms for glioma grading.

Procedures

In this study, 69 patients were examined with MRI. The T1 post enhancement (T1Gd) and diffusion-weighted images (DWI) were obtained. To evaluated LRD performance for glioma grading, we compared the parameters of the receiver operating characteristic (ROC) curves.

Findings

We found that the average Relative Signal Contrast (RSC) for high-grade gliomas is greater than RSCs for low-grade gliomas in T1Gd images and all fused images. No significant difference in RSCs of DWI images was observed between low-grade and high-grade gliomas. However, a significant RSCs difference was detected between grade III and IV in the T1Gd, b50, and all fussed images.

Conclusions

This research suggests that T1Gd images are an appropriate imaging protocol for separating low-grade and high-grade gliomas. According to the findings of this study, we may use the LRD fusion algorithm to increase the diagnostic value of T1Gd and DWI picture for grades III and IV glioma distinction. In conclusion, this article has emphasized the significance of the LRD fusion algorithm as a tool for differentiating grade III and IV gliomas.

Multi-band whole-body diffusion-weighted imaging with inversion recovery fat saturation: Effects of respiratory compensation

Purpose

To prospectively compare artefacts and image quality in testicular stage I cancer patients using different combinations of breathing schemes and Multi-band (MB) in whole-body DWIBS at 1.5 T.Diffusion-Weighted whole-body Imaging with Background body signal Suppression (DWIBS) using inversion recovery (IR) fat saturation is a cornerstone in oncologic whole-body MRI, but implementation is restrained by long acquisition times. The new Multi-Band (MB) technique reduces scan time which can be reinvested in respiratory compensation.

Methods

Thirty testicular cancer stage I patients were included. Three variations of whole-body DWIBS were tested: Standard free Breathing (FB)-DWIBS, FB-MB-DWIBS and Respiratory triggered (RT)-MB-DWIBS. Artefacts and image quality of b = 800 s/mm² images were evaluated using a Likert scale. No pathology was revealed. SNR was calculated in a healthy volunteer.

Results

RT-MB-DWIBS was rated significantly better than FB-DWIBS in the thorax (p < 0.001) and abdomen (p < 0.001), but not in the pelvis (p = 0.569). FB-MB-DWIBS was ranked significantly lower than both FB-DWIBS (p < 0.001) and RT-MB-DWIBS (p < 0.001) at all locations. However, FB-MB-DWIBS was scanned in half the time without being less than "satisfactory". Few artefacts were encountered. SNR was similar for low-intensity tissues, but the SNR in high-intensity and respiratory-prone tissue (spleen) was slightly lower for FB-DWIBS than the other sequences.

Conclusion

Images produced by the sequences were similar. MB enables the use of respiratory trigger or can be used to produce very fast free-breathing DWI with acceptable image quality.

Classifications of atherosclerotic plaque components with T1 and T2* mapping in 11.7 T MRI

BACKGROUND AND AIMS

Histopathology is the gold standard for analysis of atherosclerotic plaques but has drawbacks due to the destructive nature of the method. Ex vivo MRI is a non-destructive method to image whole plaques. Our aim was to use quantitative high field ex vivo MRI to classify plaque components, with histology as gold standard.

METHODS

Surgically resected carotid plaques from 12 patients with recent TIA or stroke were imaged at 11.7 T MRI. Quantitative T1/T2* mapping sequences and qualitative T1/T2* gradient echo sequences with voxel size of 30 × 30 × 60 μm3 were obtained prior to histological preparation, sectioning and staining for lipids, inflammation, hemorrhage, and fibrous tissue. Regions of interest (ROI) were selected based on the histological staining at multiple levels matched between histology and MRI. The MRI parameters of each ROI were then analyzed with quadratic discriminant analysis (QDA) for classification.

RESULTS

A total of 965 ROIs, at 70 levels matched between histology and MRI, were registered based on histological staining. In the nine plaques where three or more plaque components were possible to co-localize with MRI, the mean degree of misclassification by QDA was 16.5 %. One of the plaques contained mostly fibrous tissue and lipids and had no misclassifications, and two plaques mostly contained fibrous tissue. QDA generally showed good classification for fibrous tissue and lipids, whereas plaques with hemorrhage and inflammation had more misclassifications.

CONCLUSION

11.7 T ex vivo high field MRI shows good visual agreement with histology in carotid plaques. T1/T2* maps analyzed with QDA is a promising non-destructive method to classify plaque components, but with a higher degree of misclassifications in plaques with hemorrhage or inflammation.

Fat fractions from high-resolution 3D radial Dixon MRI for predicting metastatic axillary lymph nodes in breast cancer patients

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High-Resolution 3D radial Dixon MRI allows for the creation of quantitative fat fraction images.

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Lymph node fat fractions improves diagnostic performance of MRI to detect axillary lymph node metastases.

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Lymph node fat fractions are a promising quantitative indicator of metastases in axillary lymph nodes.

Purpose

To assess diagnostic performance of fat fractions (FF) from high-resolution 3D radial Dixon MRI for differentiating metastatic and non-metastatic axillary lymph nodes in breast cancer patients.

Method

High-resolution 3D radial Dixon MRI was prospectively performed on 1.5 T in 70 biopsy-verified breast cancer patients. 35 patients were available for analysis with histopathologic and imaging data. FF images were calculated as fat / in-phase. Two radiologists measured lymph node FF and assessed morphological features in one ipsilateral and one contralateral lymph node in consensus. Diagnostic performance of lymph node FF and morphological criteria were compared using histopathology as reference.

Results

22 patients had metastatic axillary lymph nodes. Mean lymph node FF were 0.20 ± 0.073, 0.31 ± 0.079, and 0.34 ± 0.15 (metastatic, non-metastatic ipsi- and non-metastatic contralateral lymph nodes, respectively). Metastatic lymph node FF were significantly lower than non-metastatic ipsi- (p <  0.001) and contralateral lymph nodes (p <  0.001). Area under the receiver operating characteristics curve for lymph node FF was 0.80 compared to 0.76 for morphological criteria (p =  0.29). Lymph node FF yielded sensitivity 0.91, specificity 0.69, positive predictive value (PPV) 0.83, and negative predictive value (NPV) 0.82, while morphological criteria yielded sensitivity 0.91, specificity 0.62, PPV 0.80, and NPV 0.80 (p =  0.71). Combining lymph node FF and morphological criteria increased diagnostic performance with sensitivity 1.00, specificity 0.67, PPV 0.86, NPV 1.00, and AUC 0.83.

Conclusions

Lymph node FF from high-resolution 3D Dixon images are a promising quantitative indicator of metastases in axillary lymph nodes.

Cardiac Involvement in Patients Recovered From COVID-2019 Identified Using Magnetic Resonance Imaging

Objectives

This study evaluated cardiac involvement in patients recovered from coronavirus disease-2019 (COVID-19) using cardiac magnetic resonance (CMR).

Background

Myocardial injury caused by COVID-19 was previously reported in hospitalized patients. It is unknown if there is sustained cardiac involvement after patients' recovery from COVID-19.

Methods

Twenty-six patients recovered from COVID-19 who reported cardiac symptoms and underwent CMR examinations were retrospectively included. CMR protocols consisted of conventional sequences (cine, T2-weighted imaging, and late gadolinium enhancement [LGE]) and quantitative mapping sequences (T1, T2, and extracellular volume [ECV] mapping). Edema ratio and LGE were assessed in post-COVID-19 patients. Cardiac function, native T1/T2, and ECV were quantitatively evaluated and compared with controls.

Results

Fifteen patients (58%) had abnormal CMR findings on conventional CMR sequences: myocardial edema was found in 14 (54%) patients and LGE was found in 8 (31%) patients. Decreased right ventricle functional parameters including ejection fraction, cardiac index, and stroke volume/body surface area were found in patients with positive conventional CMR findings. Using quantitative mapping, global native T1, T2, and ECV were all found to be significantly elevated in patients with positive conventional CMR findings, compared with patients without positive findings and controls (median [interquartile range]: native T1 1,271 ms [1,243 to 1,298 ms] vs. 1,237 ms [1,216 to 1,262 ms] vs. 1,224 ms [1,217 to 1,245 ms]; mean ± SD: T2 42.7 ± 3.1 ms vs. 38.1 ms ± 2.4 vs. 39.1 ms ± 3.1; median [interquartile range]: 28.2% [24.8% to 36.2%] vs. 24.8% [23.1% to 25.4%] vs. 23.7% [22.2% to 25.2%]; p = 0.002; p < 0.001, and p = 0.002, respectively).

Conclusions

Cardiac involvement was found in a proportion of patients recovered from COVID-19. CMR manifestation included myocardial edema, fibrosis, and impaired right ventricle function. Attention should be paid to the possible myocardial involvement in patients recovered from COVID-19 with cardiac symptoms.

Impact of aortic stiffness by velocity-encoded magnetic resonance imaging on late gadolinium enhancement to predict cardiovascular events

Background

Increased aortic stiffness has been established as a marker in various cardiovascular diseases. Previous reports revealed a significant correlation between aortic stiffness and myocardial scarring using the late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR). However, prognostic data concerning aortic stiffness combining myocardial scarring remains limited.

Method

A total of 402 patients who had undergone clinical CMR for the evaluation of cardiac function, LGE, and aortic pulse wave velocity (PWV) using velocity encoded-CMR (VE-CMR) were included. Patients were classified into 4 groups using mean PWV and the presence of LGE as elevated or non-elevated PWV and positive or negative LGE. Patients received follow-up for major adverse cardiovascular events (MACE) comprising cardiovascular death, non-fatal myocardial infarction, hospitalization for heart failure, coronary revascularization, and ischemic stroke. Predictors of MACE and hard cardiac events (cardiovascular death or non-fatal myocardial infarction) were evaluated.

Results

During the average follow-up period of 47.7 months, 58 MACE occurred. Patients who had elevated PWV and positive LGE experienced the highest rate of MACE compared to the group with non-elevated PWV and negative LGE (HR 11.90, p < 0.001). Among patients who had LGE, those who had elevated PWV experienced a 2.4-times higher rate of MACE compared to those who had non-elevated PWV. Multivariate analysis showed that PWV and LGE were independent predictors of MACE and hard cardiac events. PWV had excellent intra- and inter-observer reproducibility (intra-: ICC = 0.98, p < 0.001, inter-: ICC = 0.97, p < 0.001).

Conclusion

Aortic stiffness using VE-CMR had prognostic value to predict cardiovascular events, with the added benefits of LGE.

Prussian blue nanocubes as a multimodal contrast agent for image-guided stem cell therapy of the spinal cord

Translation of stem cell therapies to treat injuries and diseases of the spinal cord is hindered by lack of real-time monitoring techniques to guide regenerative therapies intra- and postoperatively. Thus, we developed an ultrasound (US), photoacoustic (PA), and magnetic resonance (MR) imaging approach augmented with Prussian blue nanocubes (PBNCs) to guide stem cell injections intraoperatively and monitor stem cell therapies in the spinal cord postoperatively. Per the clinical procedure, a multi-level laminectomy was performed in rats ex vivo, and PBNC-labeled stem cells were injected directly into the spinal cord while US/PA images were acquired. US/PA/MR images were also acquired post-surgery. Several features of the imaging approach were demonstrated including detection of low stem cell concentrations, real-time needle guidance and feedback on stem cell delivery, and good agreement between US/PA/MR images. These benefits span intra- and postoperative environments to support future development of this imaging tool.

4-Dimensional Flow by Cardiac Magnetic Resonance Informs Surgical Planning in Partial Anomalous Pulmonary Venous Return

Four-dimensional flow cardiac magnetic resonance enhances the visualization of blood flow in a 3-dimensional volume throughout the cardiac cycle, thus dramatically improving visualization of pulmonary venous anatomy by cardiac magnetic resonance. We demonstrate the impact of 4-dimensional flow on diagnosis and surgical planning for partial anomalous pulmonary venous return. (Level of Difficulty: Beginner.).

Common incidental findings on sacroiliac joint MRI in children clinically suspected of juvenile spondyloarthritis

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What to look for on MRI of the sacroiliac (SI) joint.

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Incidental findings are common on MRI of the sacroiliac (SI) joint in children.

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There is more to see than sacroiliitis on MRI of the sacroiliac (SI) joint.

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Degeneration, inflammation, tumor and normal variants can be seen on MRI of SI joint.

Purpose

To determine the prevalence of incidental findings on sacroiliac (SI) joint MRI in children clinically suspected of Juvenile Spondyloarthritis (JSpA).

Methods

In this retrospective multi-center study of 540 children clinically suspected of JSpA who underwent MRI of SI joints from February 2012 to May 2018, the prevalence of sacroiliitis and other incidental findings was recorded.

Results

In 106/540 (20 %) children MRI features of sacroiliitis were present. In 228 (42 %) patients MRI showed at least one incidental finding other than sacroiliitis. A total of 271 abnormal findings were reported. The most frequent incidental findings were at lumbosacral spine (158 patients, 29 %) and hip (43 patients, 8 %). The most common incidental finding was axial degenerative changes, seen in 94 patients (17 %). Other less frequent pathologies were: simple (bone) cyst in 15 (2,8 %) patients; enthesitis/tendinitis in 16 (3 %) patients; non-specific focal bone marrow edema (BME) away from SI joints in 10 (1,9 %) patients; ovarian cysts in 7 (1,3 %) patients; BME in the course of chronic recurrent multifocal osteomyelitis (CRMO) in 4 (0,7 %) patients; muscle pathology in 4 (0,7%) patients; benign tumors in 3 (0,6 %) patients; (old) fractures in 3 (0,6 %) patients; bony apophyseal avulsion in 2 (0,4 %) patients and malignant tumors in 2 (0,4 %) patients.

Conclusion

Incidental findings are common on MRI of the SI joints in children clinically suspected of JSpA, particularly at the lumbar spine and hips. They are seen even more frequently than sacroiliitis and can be relevant, as some will have clinical significance or require treatment.

Marrow adipose tissue gradient is preserved through high protein diet and bed rest. A randomized crossover study

Context

Marrow adipose tissue (MAT) has a peripheral to central distribution in adults, higher in peripheral bones. Similarly, the spine has a caudal to cephalad MAT distribution, higher in lumbar vertebras. Diet and the level of physical activities are known modulators of MAT with significant impact on bone; however, whether these can modulate the MAT gradient is unknown.

Objective

To measure the effect of high protein diet and bed rest interventions on the lumbar MAT gradient.

Design participants intervention

In a prospective randomized crossover trial, 10 healthy men participated in 2 consecutive campaigns of 21days head-down-tilt-bed-rest (HDTBR). They received either whey protein and potassium bicarbonate-supplemented or control diet separated by a 4-month washout period.

Main outcome measures

Ten serial MRI measures of lumbar vertebral fat fraction (VFF) were performed at baseline, 10days and 20days of HDTBR and 3 and 28days after HDTBR of each bed rest campaign.

Results

The mean L5-L1 VFF difference of 4.2 ± 1.2 percentage point higher at L5 (p = 0.008) constituted a caudal to cephalad lumbar MAT gradient. High protein diet did not alter the lumbar VFF differences during both HDTBR campaigns (all time points p > 0.05). Similarly, 2 campaigns of 21days of HDTBR did not change the lumbar VFF differences (all time points p > 0.05).

Conclusions

This pilot study established that the lumbar vertebral MAT gradient was not altered by a high protein nor by 2 × 21days bed rest interventions. These findings demonstrated that this lack of mechanical stimulus was not an important modulator of the lumbar MAT gradient. The highly preserved MAT gradient needs to be measured in more situations of health and disease and may potentially serve to detect pathological situations.

Assessing cortical bone mechanical properties using collagen proton fraction from ultrashort echo time magnetization transfer (UTE-MT) MRI modeling

Cortical bone shows as a signal void when using conventional clinical magnetic resonance imaging (MRI). Ultrashort echo time MRI (UTE-MRI) can acquire high signal from cortical bone, thus enabling quantitative assessments. Magnetization transfer (MT) imaging combined with UTE-MRI can indirectly assess protons in the organic matrix of bone. This study aimed to examine UTE-MT MRI techniques to estimate the mechanical properties of cortical bone. A total of 156 rectangular human cortical bone strips were harvested from the tibial and femoral midshafts of 43 donors (62 ± 22 years old, 62 specimens from females, 94 specimens from males). Bone specimens were scanned using UTE-MT sequences on a clinical 3 T MRI scanner and on a micro-computed tomography (μCT) scanner. A series of MT pulse saturation powers (400°, 600°, 800°) and frequency offsets (2, 5, 10, 20, 50 kHz) was used to measure the macromolecular fraction (MMF) utilizing a two-pool MT model. Failure mechanical properties of the bone specimens were measured using 4-point bending tests. MMF from MRI results showed significant strong correlations with cortical bone porosity (R = -0.72, P < 0.01) and bone mineral density (BMD) (R = +0.71, P < 0.01). MMF demonstrated significant moderate correlations with Young modulus, yield stress, and ultimate stress (R = 0.60-0.61, P < 0.01). These results suggest that the two-pool UTE-MT model focusing on the organic matrix of bone can potentially serve as a novel tool to detect the variations of bone mechanical properties and intracortical porosity.

Estimation of diffusion, perfusion and fractional volumes using a multi-compartment relaxation-compensated intravoxel incoherent motion (IVIM) signal model

Compartmental diffusion MRI models that account for intravoxel incoherent motion (IVIM) of blood perfusion allow for estimation of the fractional volume of the microvascular compartment. Conventional IVIM models are known to be biased by not accounting for partial volume effects caused by free water and cerebrospinal fluid (CSF), or for tissue-dependent relaxation effects. In this work, a three-compartment model (tissue, free water and blood) that includes relaxation terms is introduced. To estimate the model parameters, in vivo human data were collected with multiple echo times (TE), inversion times (TI) and b-values, which allowed a direct relaxation estimate alongside estimation of perfusion, diffusion and fractional volume parameters. Compared to conventional two-compartment models (with and without relaxation compensation), the three-compartment model showed less effects of CSF contamination. The proposed model yielded significantly different volume fractions of blood and tissue compared to the non-relaxation-compensated model, as well as to the conventional two-compartment model, suggesting that previously reported parameter ranges, using models that do not account for relaxation, should be reconsidered.

Endoscopic repair of the urinary bladder with magnetically labeled mesenchymal stem cells: Preliminary report

Introduction

Transurethral resection of a bladder tumor (TURBT) using a resectoscope has been standard treatment for bladder cancer. However, no treatment method promotes the repair of resected bladder tissue. The aim of this study was to examine the healing process of damaged bladder tissue after a transurethral injection of bone marrow mesenchymal stem cells (MSCs) into the bladder. An injection of magnetic MSCs meant that they accumulated in the damaged area of the bladder. Another aim of this study was to compare the acceleration effect of MSC magnetic delivery on the repair of bladder tissue with that of non-magnetic MSC injection.

Methods

Using the transurethral approach to avoid opening the abdomen, electrofulguration was carried out on the anterior wall of the urinary bladder of white Japanese rabbits to mimic tumor resection. An external magnetic field directed at the injured site was then applied using a 1-tesla (T) permanent magnet. Twelve rabbits were divided into three groups. The 1 × 10⁶ of magnetically labeled MSCs were injected into the urinary bladder with or without the magnetic field (MSC M+ and MSC M-groups, respectively), and phosphate-buffered saline was injected as the control. The effects of the injections in the three groups at 14 days were examined using 4.7-T magnetic resonance imaging (MRI) then macroscopically and histologically. The mRNA expressions of several cytokines in the repair tissues were assessed using real-time polymerase chain reaction.

Results

The macroscopic findings showed the area of repair tissue in the MSC M+ group to be larger than that in either the MSC M-group or control group. MRI clearly depicted the macroscopic findings. The histological study showed that repair of the cauterized area with myofibrous tissue was significantly better in the MSC M+ group than that in either the MSC M-group or control group, although there was no significant difference in several mRNA cytokines among the three groups at 14 days after surgery.

Conclusions

The magnetic delivery of MSCs shows promise as an effective, minimally invasive method of enhancing tissue regeneration after TURBT.

Reduced sound-evoked and resting-state BOLD fMRI connectivity in tinnitus

The exact neurophysiological basis of chronic tinnitus, which affects 10-15% of the population, remains unknown and is controversial at many levels. It is an open question whether phantom sound perception results from increased central neural gain or not, a crucial question for any future therapeutic intervention strategies for tinnitus. We performed a comprehensive study of mild hearing-impaired participants with and without tinnitus, excluding participants with co-occurrences of hyperacusis. A right-hemisphere correlation between tinnitus loudness and auditory perceptual difficulty was observed in the tinnitus group, independent of differences in hearing thresholds. This correlation was linked to reduced and delayed sound-induced suprathreshold auditory brain responses (ABR wave V) in the tinnitus group, suggesting subsided rather than exaggerated central neural responsiveness. When anatomically predefined auditory regions of interest were analysed for altered sound-evoked BOLD fMRI activity, it became evident that subcortical and cortical auditory regions and regions involved in sound detection (posterior insula, hippocampus), responded with reduced BOLD activity in the tinnitus group, emphasizing reduced, rather than increased, central neural gain. Regarding previous findings of evoked BOLD activity being linked to positive connectivities at rest, we additionally analysed r-fcMRI responses in anatomically predefined auditory regions and regions associated with sound detection. A profound reduction in positive interhemispheric connections of homologous auditory brain regions and a decline in the positive connectivities between lower auditory brainstem regions and regions involved in sound detection (hippocampus, posterior insula) were observed in the tinnitus group. The finding went hand-in-hand with the emotional (amygdala, anterior insula) and temporofrontal/stress-regulating regions (prefrontal cortex, inferior frontal gyrus) that were no longer positively connected with auditory cortex regions in the tinnitus group but were instead positively connected to lower-level auditory brainstem regions. Delayed sound processing, reduced sound-evoked BOLD fMRI activity and altered r-fcMRI in the auditory midbrain correlated in the tinnitus group and showed right hemisphere dominance as did tinnitus loudness and perceptual difficulty. The findings suggest that reduced central neural gain in the auditory stream may lead to phantom perception through a failure to energize attentional/stress-regulating networks for contextualization of auditory-specific information. Reduced auditory-specific information flow in tinnitus has until now escaped detection in humans, as low-level auditory brain regions were previously omitted from neuroimaging studies.

TRIAL REGISTRATION

German Clinical Trials Register DRKS0006332.

Autosomal dominant cerebellar ataxias: Imaging biomarkers with high effect sizes

Objective

As gene-based therapies may soon arise for patients with spinocerebellar ataxia (SCA), there is a critical need to identify biomarkers of disease progression with effect sizes greater than clinical scores, enabling trials with smaller sample sizes.

Methods

We enrolled a unique cohort of patients with SCA1 (n = 15), SCA2 (n = 12), SCA3 (n = 20) and SCA7 (n = 10) and 24 healthy controls of similar age, sex and body mass index. We collected longitudinal clinical and imaging data at baseline and follow-up (mean interval of 24 months). We performed both manual and automated volumetric analyses. Diffusion tensor imaging (DTI) and a novel tractography method, called fixel-based analysis (FBA), were assessed at follow-up. Effect sizes were calculated for clinical scores and imaging parameters.

Results

Clinical scores worsened as atrophy increased over time (p < 0.05). However, atrophy of cerebellum and pons showed very large effect sizes (>1.2) compared to clinical scores (<0.8). FBA, applied for the first time to SCA, was sensitive to microstructural cross-sectional differences that were not captured by conventional DTI metrics, especially in the less studied SCA7 group. FBA also showed larger effect sizes than DTI metrics.

Conclusion

This study showed that volumetry outperformed clinical scores to measure disease progression in SCA1, SCA2, SCA3 and SCA7. Therefore, we advocate the use of volumetric biomarkers in therapeutic trials of autosomal dominant ataxias. In addition, FBA showed larger effect size than DTI to detect cross-sectional microstructural alterations in patients relative to controls.

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Biomarkers are needed to test upcoming therapies for spinocerebellar ataxia.

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As spinocerebellar ataxias are rare, biomarkers with high effect sizes are needed.

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We identified imaging biomarkers with higher effect sizes than clinical scores.

Neural responses to emotional involuntary memories in posttraumatic stress disorder: Differences in timing and activity

Background

Involuntary memories are a hallmark symptom of posttraumatic stress disorder (PTSD), but studies of the neural basis of involuntary memory retrieval in posttraumatic stress disorder (PTSD) are sparse. The study of the neural correlates of involuntary memories of stressful events in PTSD focuses on the voluntary retrieval of memories that are sometimes recalled as intrusive involuntary memories, not on involuntary retrieval while being scanned. Involuntary memory retrieval in controls has been shown to elicit activity in the parahippocampal gyrus, precuneus, inferior parietal cortex, and posterior midline regions. However, it is unknown whether involuntary memories are supported by the same mechanisms in PTSD. Because previous work has shown that both behavioral and neural responsivity is slowed in PTSD, we examined the spatiotemporal dynamics of the neural activity underlying negative and neutral involuntary memory retrieval.

Methods

Twenty-one individuals with PTSD and 21 non-PTSD, trauma-exposed controls performed an involuntary memory task, while undergoing a functional magnetic resonance imaging scan. Environmental sounds served as cues for well-associated pictures of negative and neutral scenes. We used a finite impulse response model to analyze temporal differences between groups in neural responses.

Results

Compared with controls, participants with PTSD reported more involuntary memories, which were more emotional and more vivid, but which activated a similar network of regions. However, compared to controls, individuals with PTSD showed delayed neural responsivity in this network and increased vmPFC/ACC activity for negative > neutral stimuli.

Conclusions

The similarity between PTSD and controls in neural substrates underlying involuntary memories suggests that, unlike voluntary memories, involuntary memories elicit similar activity in regions critical for memory retrieval. Further, the delayed neural responsivity for involuntary memories in PTSD suggests that factors affecting cognition in PTSD, like increased fatigue, or avoidance behaviors could do so by delaying activity in regions necessary for cognitive processing. Finally, compared to neutral memories, negative involuntary memories elicit hyperactivity in the vmPFC, whereas the vmPFC is typically shown to be hypoactive in PTSD during voluntary memory retrieval. These patterns suggest that considering both the temporal dynamics of cognitive processes as well as involuntary cognitive processes would improve existing neurobiological models of PTSD.

Urgent challenges in quantification and interpretation of brain grey matter atrophy in individual MS patients using MRI

Atrophy of the brain grey matter (GM) is an accepted and important feature of multiple sclerosis (MS). However, its accurate measurement is hampered by various technical, pathological and physiological factors. As a consequence, it is challenging to investigate the role of GM atrophy in the disease process as well as the effect of treatments that aim to reduce neurodegeneration. In this paper we discuss the most important challenges currently hampering the measurement and interpretation of GM atrophy in MS. The focus is on measurements that are obtained in individual patients rather than on group analysis methods, because of their importance in clinical trials and ultimately in clinical care. We discuss the sources and possible solutions of the current challenges, and provide recommendations to achieve reliable measurement and interpretation of brain GM atrophy in MS.

Grey matter volume and cortical structure in Prader-Willi syndrome compared to typically developing young adults

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder of genomic imprinting, presenting with a characteristic overeating disorder, mild to moderate intellectual disability, and a variable range of social and behavioral difficulties. Consequently, widespread alterations in neural structure and developmental and maturational trajectory would be expected. To date, there have been few quantitative and systematic studies of brain morphology in PWS, although alterations of volume and of cortical organisation have been reported. This study aimed to investigate, in detail, the structure of grey matter and cortex in the brain in a sample of young adults with PWS in a well-matched case-controlled analysis. 20 young adults with PWS, aged 19–27 years, underwent multiparameter mapping magnetic resonance imaging sequences, from which measures of grey matter volume, cortical thickness and magnetisation transfer saturation, as a proxy measure of myelination, were examined. These variables were investigated in comparison to a control group of 40 typically developing young adults, matched for age and sex. A voxel-based morphometry analysis identified large and widespread bilateral clusters of both increased and decreased grey matter volume in the brain in PWS. In particular, widespread areas of increased volume encompassed parts of the prefrontal cortex, especially medially, the majority of the cingulate cortices, from anterior to posterior aspects, insula cortices, and areas of the parietal and temporal cortices. Increased volume was also reported in the caudate, putamen and thalamus. The most ventromedial prefrontal areas, in contrast, showed reduced volume, as did the parts of the medial temporal lobe, bilateral temporal poles, and a small cluster in the right lateral prefrontal cortex. Analysis of cortical structure revealed that areas of increased volume in the PWS group were largely driven by greater cortical thickness. Conversely, analysis of myelin content using magnetisation transfer saturation indicated that myelination of the cortex was broadly similar in the PWS and control groups, with the exception of highly localised areas, including the insula. The bilateral nature of these abnormalities suggests a systemic biological cause, with possible developmental and maturational mechanisms discussed, and may offer insight into the contribution of imprinted genes to neural development.

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Twenty young adults with PWS and forty age and sex-matched control participants underwent multiparameter mapping MRI.

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Large and widespread bilateral clusters of both increased and decreased grey matter volume were identified in PWS.

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Volumetric increases in PWS were largely driven by greater cortical thickness.

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Myelination of the cortex in PWS was broadly similar to the typically-developing control group.

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Potential developmental and maturational explanations are considered, including insights into the of the role of imprinted genes.

Evaluation of striatonigral connectivity using probabilistic tractography in Parkinson's disease

The cardinal movement abnormalities of Parkinson's disease (PD), including tremor, muscle rigidity, and reduced speed and frequency of movements, are caused by degeneration of dopaminergic neurons in the substantia nigra that project to the putamen, compromising information flow through frontal-subcortical circuits. Typically, the nigrostriatal pathway is more severely affected on the side of the brain opposite (contralateral) to the side of the body that manifests initial symptoms. Several studies have suggested that PD is also associated with changes in white matter microstructural integrity. The goal of the present study was to further develop methods for measuring striatonigral connectivity differences between PD patients and age-matched controls using diffusion weighted magnetic resonance imaging (MRI).

In this cross-sectional study, 40 PD patients and 44 controls underwent diffusion weighted imaging (DWI) using a 40-direction MRI sequence as well as an optimized 60-direction sequence with overlapping slices. Regions of interest (ROIs) encompassing the putamen and substantia nigra were hand drawn in the space of the 40-direction data using high-contrast structural images and then coregistered to the 60-direction data. Probabilistic tractography was performed in the native space of each dataset by seeding the putamen ROI with an ipsilateral substantia nigra classification target. The effect of disease group (PD versus control) on mean putamen-SN connection probability and streamline density were then analyzed using generalized linear models controlling for age, gender, education, as well as seed and target region characteristics.

Mean putamen-SN streamline density was lower in PD on both sides of the brain and in both 40- and 60-direction data. The optimized sequence provided a greater separation between PD and control means; however, individual values overlapped between groups. The 60-direction data also yielded mean connection probability values either trending (ipsilateral) or significantly (contralateral) lower in the PD group. There were minor between-group differences in average diffusion measures within the substantia nigra ROIs that did not affect the results of the GLM analyses when included as covariates. Based on these results, we conclude that mean striatonigral structural connectivity differs between PD and control groups and that use of an optimized 60-direction DWI sequence with overlapping slices increases the sensitivity of the technique to putative disease-related differences. However, overlap in individual values between disease groups limits its use as a classifier.

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The nigrostriatal pathway degenerates in Parkinson's disease.

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Two diffusion tensor imaging (DTI) sequences were acquired in 84 participants.

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Structural connectivity between putamen and substantia nigra was quantified.

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Parkinson's patients had lower connection probability and streamline density.

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A 60-direction DTI sequence with overlapping slices was most sensitive.

Characterization of Cerebral Edema in Acute-on-Chronic Liver Failure

BACKGROUND AND AIMS

The nature of cerebral edema in acute-on-chronic liver failure (ACLF) is not well studied. We aimed to characterize cerebral edema in ACLF using magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI).

METHODS

Forty-six patients with cirrhosis and acute decompensation were included. Patients were divided into groups A (no cerebral failure, n = 39) and B (cerebral failure, n = 7). Group A was subdivided into no-ACLF (n = 11), grade 1 (n = 10), grade 2 (n = 9) and grade 3 (n = 9) ACLF as per CANONIC study. MRI brain and plasma TNF-alpha, IL-1beta and IL-6 were measured at baseline and 7-10 days after admission. Ten age- and sex-matched healthy controls were also included.

RESULTS

Mean diffusivity (MD) values, an MRI marker of water content, progressively increased from controls to no-ACLF to ACLF grade 1, 2 and 3 in group A in frontal white matter (FWM) and basal ganglia (P < 0.0001). MD values improved only in survivors on follow-up. MD values correlated with IL-6 levels at baseline. On multivariate analysis MELD score ≥28 and MD values (>8 × 10^-9 M²/s) in FWM were independent predictors of 90-day mortality. There was no significant difference in clinical and MRI parameters between group A and B.

CONCLUSION

Cerebral edema increases with severity of ACLF. Correlation between MD values and IL-6 levels suggests pathogenic role of inflammation in cerebral edema. Patients with grade 3 ACLF have cerebral edema irrespective of presence of clinically evident cerebral failure. MELD score and cerebral edema have prognostic significance in ACLF.

Altered structural brain changes and neurocognitive performance in pediatric HIV

Pediatric HIV patients often suffer with neurodevelopmental delay and subsequently cognitive impairment. While tissue injury in cortical and subcortical regions in the brain of adult HIV patients has been well reported there is sparse knowledge about these changes in perinatally HIV infected pediatric patients. We analyzed cortical thickness, subcortical volume, structural connectivity, and neurocognitive functions in pediatric HIV patients and compared with those of pediatric healthy controls. With informed consent, 34 perinatally infected pediatric HIV patients and 32 age and gender matched pediatric healthy controls underwent neurocognitive assessment and brain magnetic resonance imaging (MRI) on a 3 T clinical scanner. Altered cortical thickness, subcortical volumes, and abnormal neuropsychological test scores were observed in pediatric HIV patients. The structural network connectivity analysis depicted lower connection strengths, lower clustering coefficients, and higher path length in pediatric HIV patients than healthy controls. The network betweenness and network hubs in cortico-limbic regions were distorted in pediatric HIV patients. The findings suggest that altered cortical and subcortical structures and regional brain connectivity in pediatric HIV patients may contribute to deficits in their neurocognitive functions. Further, longitudinal studies are required for better understanding of the effect of HIV pathogenesis on brain structural changes throughout the brain development process under standard ART treatment.

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Structural brain MRI and cognitive assessments were performed in pediatric HIV.

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Pediatric HIV showed altered cortical thickness and subcortical volumes.

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Disrupted structural connectivity was observed in pediatric HIV.

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Altered brain structures and connectivity contribute to deficits in neurocognition.

Perfusion magnetic resonance imaging provides additional information as compared to anatomical imaging for decision-making in vestibular schwannoma

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DSC/ASL-MRI can be acquired in growing VS with sufficient image quality.

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In most patients DSC and ASL techniques provide similar qualitative scores.

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These techniques can be of importance in future decision-making.

Objective

The added value of perfusion MRI for decision-making in vestibular schwannoma (VS) patients is unknown. MRI offers two perfusion methods: the first employing contrast agent (dynamic susceptibility contrast (DSC)-MRI) that provides information on cerebral blood volume (CBV) and cerebral blood flow (CBF), the second by magnetic labeling of blood (arterial spin labeling (ASL)-MRI), providing CBF-images. The goal of the current study is to investigate whether DSC and ASL perfusion MRI provides complimentary information to current anatomical imaging in treatment selection process of VS.

Methods

Nine patients with growing VS with extrameatal diameter >9 mm were included (>2 mm/year and 20% volume expansion/year) and one patient with 23 mm extrameatal VS without growth. DSC and ASL perfusion MRI were obtained on 3 T MRI. Perfusion in VS was scored as hyperintense, hypointense or isointense compared to the contralateral region.

Results

Seven patients showed hyperintense signal on DSC and ASL sequences. Three patients showed iso- or hypointense signal on at least one perfusion map (1 patient hypointense on both DSC-MRI and ASL; 1 patient isointense on DSC-CBF; 1 patient isointense on ASL). All patients showed enhancement on post-contrast T1 anatomical scan.

Conclusion

Perfusion MR provides additional information compared to anatomical imaging for decision-making in VS.

Hyperpolarized (13)C MR imaging detects no lactate production in mutant IDH1 gliomas: Implications for diagnosis and response monitoring

Metabolic imaging of brain tumors using (13)C Magnetic Resonance Spectroscopy (MRS) of hyperpolarized [1-(13)C] pyruvate is a promising neuroimaging strategy which, after a decade of preclinical success in glioblastoma (GBM) models, is now entering clinical trials in multiple centers. Typically, the presence of GBM has been associated with elevated hyperpolarized [1-(13)C] lactate produced from [1-(13)C] pyruvate, and response to therapy has been associated with a drop in hyperpolarized [1-(13)C] lactate. However, to date, lower grade gliomas had not been investigated using this approach. The most prevalent mutation in lower grade gliomas is the isocitrate dehydrogenase 1 (IDH1) mutation, which, in addition to initiating tumor development, also induces metabolic reprogramming. In particular, mutant IDH1 gliomas are associated with low levels of lactate dehydrogenase A (LDHA) and monocarboxylate transporters 1 and 4 (MCT1, MCT4), three proteins involved in pyruvate metabolism to lactate. We therefore investigated the potential of (13)C MRS of hyperpolarized [1-(13)C] pyruvate for detection of mutant IDH1 gliomas and for monitoring of their therapeutic response. We studied patient-derived mutant IDH1 glioma cells that underexpress LDHA, MCT1 and MCT4, and wild-type IDH1 GBM cells that express high levels of these proteins. Mutant IDH1 cells and tumors produced significantly less hyperpolarized [1-(13)C] lactate compared to GBM, consistent with their metabolic reprogramming. Furthermore, hyperpolarized [1-(13)C] lactate production was not affected by chemotherapeutic treatment with temozolomide (TMZ) in mutant IDH1 tumors, in contrast to previous reports in GBM. Our results demonstrate the unusual metabolic imaging profile of mutant IDH1 gliomas, which, when combined with other clinically available imaging methods, could be used to detect the presence of the IDH1 mutation in vivo.

Magnetic Resonance Spectroscopy: Principles and Techniques: Lessons for Clinicians

Magnetic resonance spectroscopy (MRS) provides a non-invasive 'window' on biochemical processes within the body. Its use is no longer restricted to the field of research, with applications in clinical practice increasingly common. MRS can be conducted at high magnetic field strengths (typically 11-14 T) on body fluids, cell extracts and tissue samples, with new developments in whole-body magnetic resonance imaging (MRI) allowing clinical MRS at the end of a standard MRI examination, obtaining functional information in addition to anatomical information. We discuss the background physics the busy clinician needs to know before considering using the technique as an investigative tool. Some potential applications of hepatic and cerebral MRS in chronic liver disease are also discussed.

Brain and cord myelin water imaging: a progressive multiple sclerosis biomarker

OBJECTIVES

Conventional magnetic resonance imaging (MRI) is used to diagnose and monitor inflammatory disease in relapsing remitting (RR) multiple sclerosis (MS). In the less common primary progressive (PP) form of MS, in which focal inflammation is less evident, biomarkers are still needed to enable evaluation of novel therapies in clinical trials. Our objective was to characterize the association - across the brain and cervical spinal cord - between clinical disability measures in PPMS and two potential biomarkers (one for myelin, and one for atrophy, both resulting from the same imaging technique).

METHODS

Multi-component driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) MRI of the brain and cervical spinal cord were obtained for 15 PPMS patients and 11 matched controls. Data were analysed to estimate the signal related to myelin water (VFM), as well as volume measurements. MS disability was assessed using the Multiple Sclerosis Functional Composite score, which includes measures of cognitive processing (Paced Auditory Serial Addition Test), manual dexterity (9-Hole Peg Test) and ambulatory function (Timed 25-Foot Walk); and the Expanded Disability Status Scale.

RESULTS

Brain and spinal cord volumes were different in PPMS compared to controls, particularly ventricular (+ 46%, p = 0.0006) and cervical spinal cord volume (- 16%, p = 0.0001). Brain and spinal cord myelin (VFM) were also reduced in PPMS (brain: - 11%, p = 0.01; spine: - 19%, p = 0.000004). Cognitive processing correlated with brain ventricular volume (p = 0.009). Manual dexterity correlated with brain ventricular volume (p = 0.007), and both brain and spinal cord VFM (p = 0.01 and 0.06, respectively). Ambulation correlated with spinal cord volume (p = 0.04) and spinal cord VFM (p = 0.04).

INTERPRETATION

In this study we demonstrated that mcDESPOT can be used to measure myelin and atrophy in the brain and spinal cord. Results correlate well with clinical disability scores in PPMS representing cognitive, fine motor and ambulatory disability.

Magnetic Resonance Imaging: Principles and Techniques: Lessons for Clinicians

The development of magnetic resonance imaging (MRI) for use in medical investigation has provided a huge forward leap in the field of diagnosis, particularly with avoidance of exposure to potentially dangerous ionizing radiation. With decreasing costs and better availability, the use of MRI is becoming ever more pervasive throughout clinical practice. Understanding the principles underlying this imaging modality and its multiple applications can be used to appreciate the benefits and limitations of its use, further informing clinical decision-making. In this article, the principles of MRI are reviewed, with further discussion of specific clinical applications such as parallel, diffusion-weighted, and magnetization transfer imaging. MR spectroscopy is also considered, with an overview of key metabolites and how they may be interpreted. Finally, a brief view on how the use of MRI will change over the coming years is presented.

T1rho MRI and CSF biomarkers in diagnosis of Alzheimer's disease

In the current study, we have evaluated the performance of magnetic resonance (MR) T1rho (T_1ρ) imaging and CSF biomarkers (T-tau, P-tau and Aβ-42) in characterization of Alzheimer's disease (AD) patients from mild cognitive impairment (MCI) and control subjects. With informed consent, AD (n = 27), MCI (n = 17) and control (n = 17) subjects underwent a standardized clinical assessment and brain MRI on a 1.5-T clinical-scanner. T_1ρ images were obtained at four different spin-lock pulse duration (10, 20, 30 and 40 ms). T_1ρ maps were generated by pixel-wise fitting of signal intensity as a function of the spin-lock pulse duration. T_1ρ values from gray matter (GM) and white matter (WM) of medial temporal lobe were calculated. The binary logistic regression using T_1ρ and CSF biomarkers as variables was performed to classify each group. T_1ρ was able to predict 77.3% controls and 40.0% MCI while CSF biomarkers predicted 81.8% controls and 46.7% MCI. T_1ρ and CSF biomarkers in combination predicted 86.4% controls and 66.7% MCI. When comparing controls with AD, T_1ρ predicted 68.2% controls and 73.9% AD, while CSF biomarkers predicted 77.3% controls and 78.3% for AD. Combination of T_1ρ and CSF biomarkers improved the prediction rate to 81.8% for controls and 82.6% for AD. Similarly, on comparing MCI with AD, T_1ρ predicted 35.3% MCI and 81.9% AD, whereas CSF biomarkers predicted 53.3% MCI and 83.0% AD. Collectively CSF biomarkers and T_1ρ were able to predict 59.3% MCI and 84.6% AD. On receiver operating characteristic analysis T_1ρ showed higher sensitivity while CSF biomarkers showed greater specificity in delineating MCI and AD from controls. No significant correlation between T_1ρ and CSF biomarkers, between T_1ρ and age, and between CSF biomarkers and age was observed. The combined use of T_1ρ and CSF biomarkers have promise to improve the early and specific diagnosis of AD. Furthermore, disease progression form MCI to AD might be easily tracked using these two parameters in combination.

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Increased T1rho was observed in MCI and AD compared to controls.

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Increased T-tau and P-tau and decreased Aβ1-42 were observed in MCI and AD.

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Combined biomarkers have promise to improve early and specific diagnosis of AD.

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MCI to AD progression might be tracked using these two biomarkers in combination.

Patterns of brain structural connectivity differentiate normal weight from overweight subjects

Background

Alterations in the hedonic component of ingestive behaviors have been implicated as a possible risk factor in the pathophysiology of overweight and obese individuals. Neuroimaging evidence from individuals with increasing body mass index suggests structural, functional, and neurochemical alterations in the extended reward network and associated networks.

Aim

To apply a multivariate pattern analysis to distinguish normal weight and overweight subjects based on gray and white-matter measurements.

Methods

Structural images (N = 120, overweight N = 63) and diffusion tensor images (DTI) (N = 60, overweight N = 30) were obtained from healthy control subjects. For the total sample the mean age for the overweight group (females = 32, males = 31) was 28.77 years (SD = 9.76) and for the normal weight group (females = 32, males = 25) was 27.13 years (SD = 9.62). Regional segmentation and parcellation of the brain images was performed using Freesurfer. Deterministic tractography was performed to measure the normalized fiber density between regions. A multivariate pattern analysis approach was used to examine whether brain measures can distinguish overweight from normal weight individuals.

Results

1. White-matter classification: The classification algorithm, based on 2 signatures with 17 regional connections, achieved 97% accuracy in discriminating overweight individuals from normal weight individuals. For both brain signatures, greater connectivity as indexed by increased fiber density was observed in overweight compared to normal weight between the reward network regions and regions of the executive control, emotional arousal, and somatosensory networks. In contrast, the opposite pattern (decreased fiber density) was found between ventromedial prefrontal cortex and the anterior insula, and between thalamus and executive control network regions. 2. Gray-matter classification: The classification algorithm, based on 2 signatures with 42 morphological features, achieved 69% accuracy in discriminating overweight from normal weight. In both brain signatures regions of the reward, salience, executive control and emotional arousal networks were associated with lower morphological values in overweight individuals compared to normal weight individuals, while the opposite pattern was seen for regions of the somatosensory network.

Conclusions

1. An increased BMI (i.e., overweight subjects) is associated with distinct changes in gray-matter and fiber density of the brain. 2. Classification algorithms based on white-matter connectivity involving regions of the reward and associated networks can identify specific targets for mechanistic studies and future drug development aimed at abnormal ingestive behavior and in overweight/obesity.

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Multivariate analysis can be used to classify overweight from normal weight individuals.

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Anatomical connectivity achieved 97% accuracy in the classification algorithm.

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Greater connectivity was observed in extended reward and somatosensory regions.

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Morphological gray-matter achieved 69% accuracy in the classification algorithm.

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Lower morphological values were observed in regions of the extended reward network.

Thalamic-hippocampal-prefrontal disruption in relapsing-remitting multiple sclerosis

Background

Cortical, thalamic and hippocampal gray matter atrophy in relapsing–remitting MS (RRMS) is associated cognitive deficits. However, the role of interconnecting white matter pathways including the fornix, cingulum, and uncinate fasciculus (UF) is less well studied.

Objective

To assess MS damage to a hippocampal–thalamic–prefrontal network and the relative contributions of its components to specific cognitive domains.

Methods

We calculated diffusion tensor fractional anisotropy (FA) in the fornix, cingulum and UF as well as thalamic and hippocampal volumes in 27 RRMS patients and 20 healthy controls. A neuropsychological battery was administered and 4 core tests known to be sensitive to MS changes were used to assess cognitive impairment. To determine the relationships between structure and cognition, all tests were grouped into 4 domains: attention/executive function, processing speed, verbal memory, and spatial memory. Univariate correlations with structural measures and depressive symptoms identified potential contributors to cognitive performance and subsequent linear regression determined their relative effects on performance in each domain. For significant predictors, we also explored the effects of laterality and axial versus radial diffusivity.

Results

RRMS patients had worse performance on the Symbol Digit Modalities Test, but no significant impairment in the 4 cognitive domains. RRMS had reduced mean FA of all 3 pathways and reduced thalamic and hippocampal volumes compared to controls. In RRMS we found that thalamic volume and BDI predicted attention/executive function, UF FA predicted processing speed, thalamic volume predicted verbal memory, and UF FA and BDI predicted spatial memory.

Conclusions

Hippocampal–thalamic–prefrontal disruption affects cognitive performance in early RRMS with mild to minimal cognitive impairment, confirming both white and gray matter involvement in MS and demonstrating utility in assessing functional networks to monitor cognition.

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We detect limbic white matter and gray matter insult in early RRMS patients with mild to minimal cognitive impairment.

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Thalamic atrophy and uncinate fasciculus microstructural changes are associated with cognitive performance in early RRMS.

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Depressive symptomatology also independently predicts cognitive performance

Acquisition of the pulmonary venous and left atrial anatomy with non-contrast-enhanced MRI for catheter ablation of atrial fibrillation: Usefulness of two-dimensional balanced steady-state free precession

BACKGROUND

Usually, the pulmonary venous and left atrial (PV-LA) anatomy is assessed with contrast-enhanced computed tomographic imaging for catheter ablation of atrial fibrillation (AF). A non-contrast-enhanced magnetic resonance (MR) imaging method has not been established. Three-dimensional balanced steady-state free precession (3D b-SSFP) sequences cannot visualize the PV-LA anatomy simultaneously because of the signal intensity defect of pulmonary veins. We compared two-dimensional (2D) b-SSFP sequences with 3D b-SSFP sequences in depicting the PV-LA anatomy with non-contrast-enhanced MR imaging for AF ablation.

METHODS

Eleven healthy volunteers underwent non-contrast-enhanced MR imaging with 3D b-SSFP and 2D b-SSFP sequences. The MR images were reconstructed on the 3D PV-LA surface image. Two experienced radiological technicians independently scored the multiplanar reformatted (MPR) images on a scale of 1-4 (from 1, not visualized, to 4, excellent definition). The overall score was a sum of 5 segments (LA and 4 PVs).

RESULTS

In the 2D b-SSFP method, MR imaging was successfully performed, and the 3D PV-LA surface image was precisely reconstructed in all healthy volunteers. The image score was significantly higher in the 2D b-SSFP method compared to the 3D b-SSFP method (19 [19; 20] vs. 12 [11; 15], p=0.004, for both observers). No PV signal intensity defects occurred in the 2D b-SSFP method.

CONCLUSIONS

The 2D b-SSFP sequence was more useful than the 3D b-SSFP sequence in adequately depicting the PV-LA anatomy.

Mathematical models for the diffusion magnetic resonance signal abnormality in patients with prion diseases

In clinical practice signal hyperintensity in the cortex and/or in the striatum on magnetic resonance (MR) diffusion-weighted images (DWIs) is a marker of sporadic Creutzfeldt–Jakob Disease (sCJD). MR diagnostic accuracy is greater than 90%, but the biophysical mechanisms underpinning the signal abnormality are unknown. The aim of this prospective study is to combine an advanced DWI protocol with new mathematical models of the microstructural changes occurring in prion disease patients to investigate the cause of MR signal alterations. This underpins the later development of more sensitive and specific image-based biomarkers. DWI data with a wide a range of echo times and diffusion weightings were acquired in 15 patients with suspected diagnosis of prion disease and in 4 healthy age-matched subjects. Clinical diagnosis of sCJD was made in nine patients, genetic CJD in one, rapidly progressive encephalopathy in three, and Gerstmann–Sträussler–Scheinker syndrome in two. Data were analysed with two bi-compartment models that represent different hypotheses about the histopathological alterations responsible for the DWI signal hyperintensity. A ROI-based analysis was performed in 13 grey matter areas located in affected and apparently unaffected regions from patients and healthy subjects. We provide for the first time non-invasive estimate of the restricted compartment radius, designed to reflect vacuole size, which is a key discriminator of sCJD subtypes. The estimated vacuole size in DWI hyperintense cortex was in the range between 3 and 10 µm that is compatible with neuropathology measurements. In DWI hyperintense grey matter of sCJD patients the two bi-compartment models outperform the classic mono-exponential ADC model. Both new models show that T₂ relaxation times significantly increase, fast and slow diffusivities reduce, and the fraction of the compartment with slow/restricted diffusion increases compared to unaffected grey matter of patients and healthy subjects. Analysis of the raw DWI signal allows us to suggest the following acquisition parameters for optimized detection of CJD lesions: b = 3000 s/mm² and TE = 103 ms. In conclusion, these results provide the first in vivo estimate of mean vacuole size, new insight on the mechanisms of DWI signal changes in prionopathies and open the way to designing an optimized acquisition protocol to improve early clinical diagnosis and subtyping of sCJD.

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An advanced DWI acquisition scheme was applied to 15 patients with suspected sCJD.

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Data fitting with two bi-compartment models outperformed the classic ADC model.

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In affected GM T₂ values were increased, diffusion was more hindered or restricted.

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For the first time an estimate of the restricted compartment radius was provided.

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The radius may reflect vacuole size, which is a key discriminator of sCJD subtypes.

Magnetic resonance imaging of the left atrial appendage post pulmonary vein isolation: Implications for percutaneous left atrial appendage occlusion

BACKGROUND

There is increasing interest in performing left atrial appendage (LAA) occlusion at the time of atrial fibrillation (AF) ablation procedures. However, to date there has been no description of the acute changes to the LAA immediately following pulmonary vein (PV) isolation and additional left atrium (LA) substrate modification. This study assessed changes in the size and tissue characteristics of the LAA ostium in patients undergoing PV isolation.

METHODS

This series included 8 patients who underwent cardiovascular magnetic resonance evaluation of the LA with delayed enhancement magnetic resonance imaging and contrast enhanced 3-D magnetic resonance angiography pre-, within 48 h of, and 3 months post ablation. Two independent cardiac radiologists evaluated the ostial LAA diameters and area at each time point in addition to the presence of gadolinium enhancement.

RESULTS

Compared to pre-ablation values, the respective median differences in oblique diameters and LAA area were +1.8 mm, +1.7 mm, and +0.6 cm(2) immediately post ablation (all NS) and -2.7 mm, -2.3 mm, and -0.5 cm(2) at 3 months (all NS). No delayed enhancement was detected in the LAA post ablation.

CONCLUSION

No significant change to LAA diameter, area, or tissue characteristics was noted after PV isolation. While these findings suggest the safety and feasibility of concomitant PV isolation and LAA device occlusion, the variability in the degree and direction of change of the LAA measurements highlights the need for further study.

Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease

Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD.

Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO₂.

A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD.

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Investigation of neurovascular status (NVS) in IPD using arterial spin labelling

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Diffuse prolonged arterial arrival time in IPD compared to controls

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Reduced regional CBF in the IPD group correlated with cognitive impairment.

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Clinical evidence of altered NVS in IPD warrants further research.

Increased cortical curvature reflects white matter atrophy in individual patients with early multiple sclerosis

Objective

White matter atrophy occurs independently of lesions in multiple sclerosis. In contrast to lesion detection, the quantitative assessment of white matter atrophy in individual patients has been regarded as a major challenge. We therefore tested the hypothesis that white matter atrophy (WMA) is present at the very beginning of multiple sclerosis (MS) and in virtually each individual patient. To find a new sensitive and robust marker for WMA we investigated the relationship between cortical surface area, white matter volume (WMV), and whole-brain-surface-averaged rectified cortical extrinsic curvature. Based on geometrical considerations we hypothesized that cortical curvature increases if WMV decreases and the cortical surface area remains constant.

Methods

In total, 95 participants were enrolled: 30 patients with early and advanced relapsing–remitting MS; 30 age-matched control subjects; 30 patients with Alzheimer's disease (AD) and 5 patients with clinically isolated syndrome (CIS).

Results

29/30 MS and 5/5 CIS patients showed lower WMV than expected from their intracranial volume (average reduction 13.0%, P < 10^− 10), while the cortical surface area showed no significant differences compared with controls. The estimated WMV reductions were correlated with an increase in cortical curvature (R = 0.62, P = 0.000001). Discriminant analysis revealed that the curvature increase was highly specific for the MS and CIS groups (96.7% correct assignments between MS and control groups) and was significantly correlated with reduction of white matter fractional anisotropy, as determined by diffusion tensor imaging and the Expanded Disability Status Scale. As expected by the predominant gray and WM degeneration in AD, no systematic curvature increase was observed in AD.

Conclusion

Whole-brain-averaged cortical extrinsic curvature appears to be a specific and quantitative marker for a WMV–cortex disproportionality and allows us to assess “pure” WMA without being confounded by intracranial volume. WMA seems to be a characteristic symptom in early MS and can already occur in patients with CIS and should thus be considered in future MS research and clinical studies.

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We suggest cortical curvature as marker for selective white matter atrophy (WMA).

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This geometric marker is more specific and sensitive than volumetric measures.

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It is not confounded by intra-cranial volume, age, and gender.

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WMA seems to be a characteristic symptom in early multiple sclerosis.

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WMA can be also detected in patients with a clinical isolated symptom.

Diffusion-weighted MRI for detecting prostate tumour in men at increased genetic risk

BACKGROUND

Diffusion-weighted (DW)-MRI is invaluable in detecting prostate cancer. We determined its sensitivity and specificity and established interobserver agreement for detecting tumour in men with a family history of prostate cancer stratified by genetic risk.

METHODS

51 men with a family history of prostate cancer underwent T2-W + DW-endorectal MRI at 3.0 T. Presence of tumour was noted at right and left apex, mid and basal prostate sextants by 2 independent observers, 1 experienced and the other inexperienced in endorectal MRI. Sensitivity and specificity against a 10-core sampling technique (lateral and medial cores at each level considered together) in men with >2× population risk based on 71 SNP analysis versus those with lower genetic risk scores was established. Interobserver agreement was determined at a subject level.

RESULTS

Biopsies indicated cancer in 28 sextants in 13/51 men; 32 of 51 men had twice the population risk (>0.25) based on 71 SNP profiling. Sensitivity/specificity per-subject for patients was 90.0%/86.4% (high-risk) vs. 66.7%/100% (low-risk, observer 1) and 60.0%/86.3% (high-risk) vs. 33.3%/93.8% (low-risk, observer 2) with moderate overall inter-observer agreement (kappa = 0.42). Regional sensitivities/specificities for high-risk vs. low-risk for observer 1 apex 72.2%/100% [33.3%/100%], mid 100%/93.1% [100%/97.3%], base 16.7%/98.3% [0%/100%] and for observer 2 apex 36.4%/98.1% [0%/100%], mid 28.6%/96.5% [100%/100%], base 20%/100% [0%/97.3%] were poorer as they failed to detect multiple lesions.

CONCLUSION

Endorectal T2W + DW-MRI at 3.0 T yields high sensitivity and specificity for tumour detection by an experienced observer in screening men with a family history of prostate cancer and increased genetic risk.

White matter structural connectivity is associated with sensorimotor function in stroke survivors

Purpose

Diffusion tensor imaging (DTI) provides functionally relevant information about white matter structure. Local anatomical connectivity information combined with fractional anisotropy (FA) and mean diffusivity (MD) may predict functional outcomes in stroke survivors. Imaging methods for predicting functional outcomes in stroke survivors are not well established. This work uses DTI to objectively assess the effects of a stroke lesion on white matter structure and sensorimotor function.

Methods

A voxel-based approach is introduced to assess a stroke lesion's global impact on motor function. Anatomical T1-weighted and diffusion tensor images of the brain were acquired for nineteen subjects (10 post-stroke and 9 age-matched controls). A manually selected volume of interest was used to alleviate the effects of stroke lesions on image registration. Images from all subjects were registered to the images of the control subject that was anatomically closest to Talairach space. Each subject's transformed image was uniformly seeded for DTI tractography. Each seed was inversely transformed into the individual subject space, where DTI tractography was conducted and then the results were transformed back to the reference space. A voxel-wise connectivity matrix was constructed from the fibers, which was then used to calculate the number of directly and indirectly connected neighbors of each voxel. A novel voxel-wise indirect structural connectivity (VISC) index was computed as the average number of direct connections to a voxel's indirect neighbors. Voxel-based analyses (VBA) were performed to compare VISC, FA, and MD for the detection of lesion-induced changes in sensorimotor function. For each voxel, a t-value was computed from the differences between each stroke brain and the 9 controls. A series of linear regressions was performed between Fugl-Meyer (FM) assessment scores of sensorimotor impairment and each DTI metric's log number of voxels that differed from the control group.

Results

Correlation between the logarithm of the number of significant voxels in the ipsilesional hemisphere and total Fugl-Meyer score was moderate for MD (R2 = 0.512), and greater for VISC (R2 = 0.796) and FA (R2 = 0.674). The slopes of FA (p = 0.0036), VISC (p = 0.0005), and MD (p = 0.0199) versus the total FM score were significant. However, these correlations were driven by the upper extremity motor component of the FM score (VISC: R2 = 0.879) with little influence of the lower extremity motor component (FA: R2 = 0.177).

Conclusion

The results suggest that a voxel-wise metric based on DTI tractography can predict upper extremity sensorimotor function of stroke survivors, and that supraspinal intraconnectivity may have a less dominant role in lower extremity function.

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An intrinsic voxel-based structural connectivity metric is proposed.

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The metric enhances the impact of stroke lesions on the distant voxels.

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Whole-brain extralesional anatomical connectivity predicts functional outcome.

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Functional impact of a lesion is determined by residual anatomical connectivity.

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Connectivity to the posterior parietal cortex is a key to sensorimotor function.

Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults.

We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants.

Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism.