Conventional Clinical Imaging Research Articles

Gleason Probability Maps: A Radiomics Tool for Mapping Prostate Cancer Likelihood in MRI Space.

Prostate cancer is the most common noncutaneous cancer in men in the United States. The current paradigm for screening and diagnosis is imperfect, with relatively low specificity, high cost, and high morbidity. This study aims to generate new image contrasts by learning a distribution of unique image signatures associated with prostate cancer. In total, 48 patients were prospectively recruited for this institutional review board–approved study. Patients underwent multiparametric magnetic resonance imaging 2 weeks before surgery. Postsurgical tissues were annotated by a pathologist and aligned to the in vivo imaging. Radiomic profiles were generated by linearly combining 4 image contrasts (T2, apparent diffusion coefficient [ADC] 0-1000, ADC 50-2000, and dynamic contrast-enhanced) segmented using global thresholds. The distribution of radiomic profiles in high-grade cancer, low-grade cancer, and normal tissues was recorded, and the generated probability values were applied to a naive test set. The resulting Gleason probability maps were stable regardless of training cohort, functioned independent of prostate zone, and outperformed conventional clinical imaging (area under the curve [AUC] = 0.79). Extensive overlap was seen in the most common image signatures associated with high- and low-grade cancer, indicating that low- and high-grade tumors present similarly on conventional imaging.

The efficacy of added shear wave elastography (SWE) in breast screening for women with inconsistent mammography and conventional ultrasounds (US).

To evaluate the efficacy of added shear wave elastography (SWE) in breast screening for women with results inconsistent between mammography and conventional ultrasounds (US). The study consisted of 282 pathologically proven breast lesions. The cancer probability from screening by mammography and conventional US were scored using Breast Imaging Reporting and Data System (BI-RADS). Elastography was used to re-evaluate inconsistent conventional US and mammography results. The diagnostic performance of conventional US, mammography, and Combined conventional clinical imaging and SWE was compared. The clinicopathological features of all breast cancer patients with inconsistent (and consistent) conventional US and mammography findings were compared. Finally, 147 lesions were confirmed benign and 135 were malignant. The AUC of Combined conventional clinical imaging plus elastography imaging (0.870) was significantly higher than mammography (0.735, p < 0.001) or conventional US (0.717, p < 0.001) alone. Among the 135 breast cancers, 79 of the conventional US and mammography findings were consistent and 56 were inconsistent. Younger age(<50y) (p = 0.035), non-invasive (p = 0.037), smaller size (p = 0.002) and negative lymph node status (p = 0.026) were significantly associated with inconsistent findings. The added SWE in breast screening when inconsistent results from mammography and conventional US occurred is necessary and effective.

Real-time Volumetric Assessment of the Human Carotid Artery: Handheld Multispectral Optoacoustic Tomography

Background Multispectral optical imaging has the capability of resolving hemoglobin, lipid, and water. Volumetric multispectral optoacoustic tomography (MSOT) is a hybrid imaging technique that provides a unique combination of functional and molecular contrast with real-time handheld imaging. Purpose To investigate whether volumetric MSOT can provide real-time assessment of the anatomic and functional status of the human carotid artery bifurcation noninvasively. Materials and Methods Imaging of healthy volunteers (n = 16) was performed with a custom-designed handheld volumetric MSOT scanner capable of high-spatial-resolution (approximately 200 µm) and real-time (10 volumes/sec) three-dimensional imaging, while further providing spectroscopic capacity through fast tuning of the excitation light wavelength. For comparison and anatomic cross-validation, volunteers were also scanned with clinical B-mode US. Results Volumetric MSOT achieved real-time imaging and characterization of the entire carotid bifurcation area across three dimensions simultaneously captured in a single volumetric image frame. Analysis of the acquired data further showed that a higher contrast-to-noise ratio can be achieved for wavelengths corresponding to a high optical absorption of oxygenated hemoglobin. Conclusion The human carotid artery was visualized by using handheld volumetric multispectral optoacoustic tomography. This imaging approach is less prone to motion artifacts than are the conventional clinical imaging methods, holding promise for providing additional image-based biomarkers for noninvasive label-free assessment of carotid artery disease. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Mezrich in this issue.

Assessing photoreceptor structure in patients with traumatic head injury

ObjectivePrevious work using adaptive optics scanning light ophthalmoscopy (AOSLO) imaging has shown photoreceptor disruption to be a common finding in head and ocular trauma patients. Here an expanded trauma population...

PS02.195: CIRCULATING TUMOUR DNA HAS UTILITY IN THE CLINICAL MANAGEMENT OF ESOPHAGEAL CANCER

Abstract Background Cell-free DNA, a consequence of normal cell death and apoptosis, is found in the blood of all individuals. In cancer patients, a proportion of circulating cell free DNA will be derived from tumour cells, and is termed circulating tumour DNA (ctDNA).We have developed a blood-based ‘liquid biopsy’ to detect ctDNA in plasma of esophageal cancer patients. Methods Tumour, buffy-coat (germline) and plasma samples were obtained from 28 esophageal cancer patients at the time of diagnosis. Serial blood samples were collected from 8 patients. Somatic DNA mutations in 9 genes (TP53, ARID1A, SMAD4, CDKN2A, SMARCA4, NRG1, APC, PIK3CA and KRAS) were evaluated in tumour biopsies and plasma using targeted sequencing. Tumour specific mutations were confirmed by droplet digital PCR, which was used to track patient-specific ctDNA in plasma from serially collected blood samples. Results Somatic mutations in at least one of the targeted genes were detected in 19/28 (68%) tumour biopsies. The same mutations were detected in ctDNA from plasma in 9/19 (48%) patients. Additional mutations that were not detected in the tumour biopsies were detected in plasma DNA from 2 patients, highlighting the issues of intra-tumoural heterogeneity and sampling bias of tumour biopsies. ctDNA was more frequently detected in patients with advanced disease where it represented a greater proportion of the total cell-free plasma DNA than in patients with localised disease. In patients with serial samples, levels of ctDNA correlated with response to treatment, and rises in ctDNA could be detected prior to clinical evidence of relapse. Conclusion Detection of ctDNA using targeted sequencing and digital PCR is feasible in the majority of esophageal cancer patients, particularly those with advanced disease. Dynamic changes in ctDNA levels reflect response to treatment and disease relapse as determined by conventional clinical imaging. We conclude that ctDNA levels can provide supplemental evidence regarding disease staging, as well as prognostic and predictive information that can inform therapeutic pathway decisions in esophageal cancer patients. Disclosure All authors have declared no conflicts of interest.

Abstract IA15: Targeting oligometastatic disease in prostate cancer

Abstract Clinical reports of limited and treatable cancer metastases, a disease state that exists in a transitional zone between localized and widespread systemic disease, have been noted on occasion historically and termed oligometastasis (OM). The ramification of a diagnosis of oligometastasis is a change in treatment paradigm, i.e., if the primary cancer site (if still present) is controlled or resected, and the metastatic sites are ablated (surgically or with radiation), a prolonged disease-free interval, and perhaps even cure, may be possible. Contemporary imaging diagnostics are identifying more and more OM patients. For example, in prostate cancer the use of PSMA-Pyl PET imaging is leading to the diagnosis of many OM patients who have no disease on conventional clinical imaging. It is unclear if these are truly isolated sites of disease (curable) or simply a reflection of more widespread microscopic disease (incurable or at best a bridging therapy). This is especially true in the biochemical recurrence (bcr) space after primary treatment. We will present our experience with identifying and treating prostate cancer OM disease. Citation Format: Kenneth J. Pienta. Targeting oligometastatic disease in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr IA15.

New trends in the orthopaedic management of diabetic foot.

Although there are various types of therapeutic footwear currently used to treat diabetic foot ulcers (DFUs), recent literature has enforced the concept that total-contact casts are the benchmark.Besides conventional clinical tests and imaging modalities, advanced MRI techniques and high-sensitivity nuclear medicine modalities present several advantages for the investigation of diabetic foot problems.The currently accepted principles of DFU care are rigorous debridement followed by modern wound dressings to provide a moist wound environment. Recently, hyperbaric oxygen and negative pressure wound therapy have aroused increasing attention as an adjunctive treatment for patients with DFUs.For DFU, various surgical treatments are currently available, including resection arthroplasty, metatarsal osteotomies and metatarsal head resections.In the modern management of the Charcot foot, surgery in the acute phase remains controversial and under investigation. While conventional fixation techniques are frequently insufficient to keep alignment postoperatively, superconstruct techniques could provide a successful fixation.Retrograde intramedullary nailing has been a generally accepted method of achieving stability. The midfoot fusion bolt is a current treatment device that maintains the longitudinal columns of the foot. Also, Achilles tendon lengthening remains a popular method in the management of Charcot foot.Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170073

A 1-minute full brain MR exam using a multicontrast EPI sequence.

A new multicontrast echo-planar imaging (EPI)-based sequence is proposed for brain MRI, which can directly generate six MR contrasts (T1 -FLAIR, T2 -w, diffusion-weighted (DWI), apparent diffusion coefficient (ADC), T2*-w, T2 -FLAIR) in 1 min with full brain coverage. This could enable clinical MR clinical screening in similar time as a conventional CT exam but with more soft-tissue information. Eleven sequence modules were created as dynamic building blocks for the sequence. Two EPI readout modules were reused throughout the sequence and were prepended by other modules to form the desired MR contrasts. Two scan protocols were optimized with scan times of 55-75 s. Motion experiments were carried out on two volunteers to investigate the robustness against head motion. Scans on patients were carried out and compared to conventional clinical images. The pulse sequence is found to be robust against motion given its single-shot nature of each contrast. For excessive out-of-plane head motion, the T1 -FLAIR and T2 -FLAIR contrasts suffer from incomplete inversion. Despite lower signal-to-noise ratio (SNR) and resolution, the 1-min multicontrast EPI data show promising correspondence with conventional diagnostic scans on patients. A 1 min multicontrast brain MRI scan based on EPI readouts has been presented in this feasibility study. Preliminary data show potential for clinical brain MRI use with minimal bore time for the patient. Such short examination time could be useful (e.g., for screening and acute stroke). The sequence may also help planning conventional brain MRI scans if run at the beginning of an examination. Magn Reson Med 79:3045-3054, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Validation of the Gatortail method for accurate sizing of pulmonary vessels from 3D medical images.

Detailed characterization of changes in vessel size is crucial for the diagnosis and management of a variety of vascular diseases. Because clinical measurement of vessel size is typically dependent on the radiologist's subjective interpretation of the vessel borders, it is often prone to high inter- and intra-user variability. Automatic methods of vessel sizing have been developed for two-dimensional images but a fully three-dimensional (3D) method suitable for vessel sizing from volumetric X-ray computed tomography (CT) or magnetic resonance imaging has heretofore not been demonstrated and validated robustly. In this paper, we refined and objectively validated Gatortail, a method that creates a mathematical geometric 3D model of each branch in a vascular tree, simulates the appearance of the virtual vascular tree in a 3D CT image, and uses the similarity of the simulated image to a patient's CT scan to drive the optimization of the model parameters, including vessel size, to match that of the patient. The method was validated with a 2-dimensional virtual tree structure under deformation, and with a realistic 3D-printed vascular phantom in which the diameter of 64 branches were manually measured 3 times each. The phantom was then scanned on a conventional clinical CT imaging system and the images processed with the in-house software to automatically segment and mathematically model the vascular tree, label each branch, and perform the Gatortail optimization of branch size and trajectory. Previously proposed methods of vessel sizing using matched Gaussian filters and tubularity metrics were also tested. The Gatortail method was then demonstrated on the pulmonary arterial tree segmented from a human volunteer's CT scan. The standard deviation of the difference between the manually measured and Gatortail-based radii in the 3D physical phantom was 0.074mm (0.087 in-plane pixel units for image voxels of dimension 0.85×0.85×1.0mm) over the 64 branches, representing vessel diameters ranging from 1.2 to 7mm. The linear regression fit gave a slope of 1.056 and an R2 value of 0.989. These three metrics reflect superior agreement of the radii estimates relative to previously published results over all sizes tested. Sizing via matched Gaussian filters resulted in size underestimates of >33% over all three test vessels, while the tubularity-metric matching exhibited a sizing uncertainty of >50%. In the human chest CT data set, the vessel voxel intensity profiles with and without branch model optimization showed excellent agreement and improvement in the objective measure of image similarity. Gatortail has been demonstrated to be an automated, objective, accurate and robust method for sizing of vessels in 3D non-invasively from chest CT scans. We anticipate that Gatortail, an image-based approach to automatically compute estimates of blood vessel radii and trajectories from 3D medical images, will facilitate future quantitative evaluation of vascular response to disease and environmental insult and improve understanding of the biological mechanisms underlying vascular disease processes.

Advanced MR Imaging Techniques for Differentiation of Neuropathic Arthropathy and Osteomyelitis in the Diabetic Foot.

Diagnosis and treatment of foot disease in patients with diabetes is a common clinical-radiologic challenge, particularly the differentiation of neuropathic arthropathy from osteomyelitis. Conventional clinical tests and imaging techniques have limited accuracy for evaluation of the diabetic foot. The introduction of morphologic magnetic resonance (MR) imaging in these patients has provided a qualitative leap in diagnosis. The characteristics of soft-tissue and bone marrow edema and their patterns of distribution throughout the foot allow discrimination between both entities. However, in certain scenarios, the application of MR imaging to this problem is limited because of overlapping features between the two and the coexistence of infection and neuropathic changes. Recent technical advances in MR imaging sequences have increased the capability to add functional quantitative information to structural information. Diffusion-weighted imaging is useful to determine the presence and extension of osteomyelitis. Dynamic contrast-enhanced MR imaging may help to detect differences between the vascularization patterns of neuropathic arthropathy and osteomyelitis. MR angiography (with or without contrast material) is used in clinical practice to identify candidate distal vessels for revascularization. MR neurography, and especially diffusion-tensor imaging, provides quantitative information about neural damage. These new sequences may help in assessment of the different pathophysiologic conditions that occur in the diabetic foot. The physical basis of these techniques, their limitations, and their potential applications for diabetic foot assessment are detailed in this article. The introduction of advanced MR imaging multiparametric protocols, with the aim of enhancing the overall diagnostic accuracy of MR imaging, may help in treatment decision making and lead to improved patient outcomes. © RSNA, 2017.

Structural imaging of mild traumatic brain injury may not be enough: overview of functional and metabolic imaging of mild traumatic brain injury

A majority of patients with traumatic brain injury (TBI) present as mild injury with no findings on conventional clinical imaging methods. Due to this difficulty of imaging assessment on mild TBI patients, there has been much emphasis on the development of diffusion imaging modalities such as diffusion tensor imaging (DTI). However, basic science research in TBI shows that many of the functional and metabolic abnormalities in TBI may be present even in the absence of structural damage. Moreover, structural damage may be present at a microscopic and molecular level that is not detectable by structural imaging modality. The use of functional and metabolic imaging modalities can provide information on pathological changes in mild TBI patients that may not be detected by structural imaging. Although there are various differences in protocols of positron emission tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and magnetoencephalography (MEG) methods, these may be important modalities to be used in conjunction with structural imaging in the future in order to detect and understand the pathophysiology of mild TBI. In this review, studies of mild TBI patients using these modalities that detect functional and metabolic state of the brain are discussed. Each modality's advantages and disadvantages are compared, and potential future applications of using combined modalities are explored.

Delivering Therapy to target: Improving the Odds for Successful Drug Development

The direct delivery of drugs and other agents into tissue (in contrast to systemic administration) has been used in clinical trials for brain cancer, neurodegenerative diseases and peripheral tumors. However, continuing evidence suggests that clinical efficacy depends on adequate delivery to a target. Inadequate delivery may have doomed otherwise effective drugs, through failure to distinguish drug inefficacy from poor distribution at the target. Conventional pretreatment clinical images of the patient fail to reveal the complexity and diversity of drug transport pathways in tissue. We discuss the richness of these pathways and argue that development and patient treatment can be sped up and improved by: using quantitative as well as 'real-time' imaging; customized simulations using data from that imaging; and device designs that optimize the drug-device combination.

Detection of Post-Therapeutic Effects in Breast Carcinoma Using Hard X-Ray Index of Refraction Computed Tomography – A Feasibility Study

ObjectivesNeoadjuvant chemotherapy is the state-of-the-art treatment in advanced breast cancer. A correct visualization of the post-therapeutic tumor size is of high prognostic relevance. X-ray phase-contrast computed tomography (PC-CT) has been shown to provide improved soft-tissue contrast at a resolution formerly restricted to histopathology, at low doses. This study aimed at assessing ex-vivo the potential use of PC-CT for visualizing the effects of neoadjuvant chemotherapy on breast carcinoma.Materials and MethodsThe analysis was performed on two ex-vivo formalin-fixed mastectomy samples containing an invasive carcinoma removed from two patients treated with neoadjuvant chemotherapy. Images were matched with corresponding histological slices. The visibility of typical post-therapeutic tissue changes was assessed and compared to results obtained with conventional clinical imaging modalities.ResultsPC-CT depicted the different tissue types with an excellent correlation to histopathology. Post-therapeutic tissue changes were correctly visualized and the residual tumor mass could be detected. PC-CT outperformed clinical imaging modalities in the detection of chemotherapy-induced tissue alterations including post-therapeutic tumor size.ConclusionsPC-CT might become a unique diagnostic tool in the prediction of tumor response to neoadjuvant chemotherapy. PC-CT might be used to assist during histopathological diagnosis, offering a high-resolution and high-contrast virtual histological tool for the accurate delineation of tumor boundaries.

PET Imaging of Atherosclerotic Disease: Advancing Plaque Assessment from Anatomy to Pathophysiology.

Atherosclerosis is a leading cause of morbidity and mortality. It is now widely recognized that the disease is more than simply a flow-limiting process and that the atheromatous plaque represents a nidus for inflammation with a consequent risk of plaque rupture and atherothrombosis, leading to myocardial infarction or stroke. However, widely used conventional clinical imaging techniques remain anatomically focused, assessing only the degree of arterial stenosis caused by plaques. Positron emission tomography (PET) has allowed the metabolic processes within the plaque to be detected and quantified directly. The increasing armory of radiotracers has facilitated the imaging of distinct metabolic aspects of atherogenesis and plaque destabilization, including macrophage-mediated inflammatory change, hypoxia, and microcalcification. This imaging modality has not only furthered our understanding of the disease process in vivo with new insights into mechanisms but has also been utilized as a non-invasive endpoint measure in the development of novel treatments for atherosclerotic disease. This review provides grounding in the principles of PET imaging of atherosclerosis, the radioligands in use and in development, its research and clinical applications, and future developments for the field.

Continuous evolution of magnetic resonance imaging in multiple sclerosis.

Since the introduction of MR imaging into routine clinical practice in the 1990s, it has become firmly embedded into the diagnostic criteria of multiple sclerosis (MS). Furthermore, serial MR brain imaging is increasingly being used to complement contemporary clinical assessment of MS disease activity. Clinical imaging in MS largely relies upon the detection of T2-hyperintense and T1-gadolinium enhancing lesions, as surrogate markers of foci of inflammatory demyelination in the white matter. Beyond the scope of conventional clinical imaging, advanced MR technology is now capable of detecting and quantifying pathology in tissue compartments previously thought to be unaffected in MS. The appreciation of microscopic damage within the “normal-appearing white matter” and grey matter of the brain and spinal cord has considerably advanced our knowledge of the pathophysiology of MS. In this month’s journal club we describe three papers that relate to MR imaging in MS. This first paper describes the latest MR criteria for MS diagnosis. The second paper describes the imaging characteristics of the radiologically isolated syndrome and how they, along with clinical factors, relate to the subsequent onset of symptomatic demyelinating disease. The third paper uses advanced MR technology to uncover the regional pattern of cortical atrophy in MS and its relationship to white matter pathology and clinical disability.

Sample-size calculations for short-term proof-of-concept studies of tissue protection and repair in multiple sclerosis lesions via conventional clinical imaging

Background: New multiple sclerosis (MS) lesion activity on magnetic resonance imaging (MRI) can test immunomodulatory therapies in proof-of-concept trials. Comparably powerful endpoints to assess tissue protection or repair are lacking. Objective: The objective of this paper is to report sample-size calculations for assessment of new lesion recovery. Methods: In two sets of six active MS cases, new lesions were observed by monthly MRI for approximately 12 months. Averages and quartiles of normalized (proton density/T1/T2 weighted) and quantitative (T1/T2 and mean diffusivity maps for dataset 1, T2 and magnetization transfer ratio maps for dataset 2) measures were used to compare the lesion area before lesion appearance to afterward. A linear mixed-effects model incorporating lesion- and participant-specific random effects estimated average levels and variance components for sample-size calculations. Results: In both datasets, greatest statistical sensitivity was observed for the 25th percentile of normalized proton density-weighted signal. At 3T, using new lesions ⩾15 mm3, as few as nine participants/arm may be required for a six-month placebo-controlled add-on trial postulating a therapeutic effect size of 20% and statistical power of 90%. Conclusion: Lesion recovery is a powerful outcome measure for proof-of-concept clinical trials of tissue protection and repair in MS. The trial design requires active cases and is therefore best implemented near disease onset.

Chapter 20 - Advances in imaging explosive blast mild traumatic brain injury

In the past, direct physical evidence of mild traumatic brain injury (mTBI) from explosive blast has been difficult to obtain through conventional imaging modalities such as T1- and T2-weighted magnetic resonance imaging (MRI) and computed tomography (CT). Here, we review current progress in detecting evidence of brain injury from explosive blast using advanced imaging, including diffusion tensor imaging (DTI), functional MRI (fMRI), and the metabolic imaging methods such as positron emission tomography (PET) and magnetic resonance spectroscopic imaging (MRSI), where each targets different aspects of the pathology involved in mTBI. DTI provides a highly sensitive measure to detect primary changes in the microstructure of white matter tracts. fMRI enables the measurement of changes in brain activity in response to different stimuli or tasks. Remarkably, all three of these paradigms have found significant success in conventional mTBI where conventional clinical imaging frequently fails to provide definitive differences. Additionally, although used less frequently for conventional mTBI, PET has the potential to characterize a variety of neurotransmitter systems using target agents and will undoubtedly play a larger role, once the basic mechanisms of injury are better understood and techniques to identify the injury are more common. Finally, our MRSI imaging studies, although acquired at much lower spatial resolution, have demonstrated selectivity to different metabolic and physiologic processes, uncovering some of the most profound differences on an individual by individual basis, suggesting the potential for utility in the management of individual patients.

Initial study of biexponential model of intravoxel incoherent motion magnetic resonance imaging in evaluation of the liver fibrosis.

The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging. Intravoxel incoherent motion (IVIM) can be used to investigate both diffusion and perfusion changes in tissues. This study was designed to determine the value of IVIM in the diagnosis and staging of liver fibrosis. IVIM examinations were performed on a GE 3.0T MR scanner in 25 patients with liver fibrosis and 25 healthy volunteers as the control group. Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of F0-4. The standard ADC values and the values of a biexponential model (slow ADC (Dslow), fast ADC (Dfast) and fraction of fast ADC (FF)) were measured in three liver regions per person. The mean standard ADC values, Dslow values, Dfast values and FF values from the study group were compared among the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe. Receiver Operating Characteristic (ROC) curves and independent-samples t-tests were used to calculate the mean standard ADC values, Dslow values, Dfast values and FF values from the study group and the control group. Spearman rho correlation analysis was used for the stage of liver fibrosis. The liver fibrosis stages between the groups F0-1 and F2-4, the groups F0-2 and F3-4 were compared. Among the liver fibrosis, there was no significant difference in the mean standard ADC values, Dslow values, Dfast values, and FF values obtained from the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe. Using ROC analysis, the Area Under the Curve (AUC) values of standard ADC, Dslow, Dfast, FF were all between 0.7 to 0.9. The mean standard ADC values, Dslow values, Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group (P < 0.05). As the stage of the fibrosis increased, the values decreased by Spearman rho correlation analysis. The mean values (standard ADC, Dslow, Dfast, and FF) of liver fibrosis stages between the groups F0-1 and F2-4, the groups F0-2 and F3-4 showed significant differences (P < 0.05). IVIM can reflect the conditions of perfusion and diffusion in liver fibrosis and thus distinguish between normal liver and liver fibrosis. The IVIM technique may serve as a valuable tool for detecting and characterizing liver fibrosis, and monitoring its progression in a noninvasive manner.

Magnetic resonance imaging assessed cortical porosity is highly correlated with μCT porosity

Cortical bone is typically regarded as “MR invisible” with conventional clinical magnetic resonance imaging (MRI) pulse sequences. However, recent studies have demonstrated that free water in the microscopic pores of cortical bone has a short T2* but a relatively long T2, and may be detectable with conventional clinical spin echo (SE) or fast spin echo (FSE) sequences. In this study we describe the use of a conventional two-dimensional (2D) FSE sequence to assess cortical bone microstructure and measure cortical porosity using a clinical 3T scanner. Twelve cadaveric human cortical bone samples were studied with MRI and microcomputed tomography (μCT) (downsampled to the same spatial resolution). Preliminary results show that FSE-determined porosity is highly correlated (R2=0.83; P<0.0001) with μCT porosity. Bland–Altman analysis suggested a good agreement between FSE and μCT with tight limit of agreement at around 3%. There is also a small bias of −2% for the FSE data, which suggested that the FSE approach slightly underestimated μCT porosity. The results demonstrate that cortical porosity can be directly assessed using conventional clinical FSE sequences. The clinical feasibility of this approach was also demonstrated on six healthy volunteers using 2D FSE sequences as well as 2D ultrashort echo time (UTE) sequences with a minimal echo time (TE) of 8μs, which provide high contrast imaging of cortical bone in vivo.

Prevalence and Spectrum of In Utero Structural Brain Abnormalities in Fetuses with Complex Congenital Heart Disease

Brain injury is a major complication in neonates with complex congenital heart disease. Preliminary evidence suggests that fetuses with congenital heart disease are at greater risk for brain abnormalities. However, the nature and frequency of these brain abnormalities detected by conventional fetal MR imaging has not been examined prospectively. Our primary objective was to determine the prevalence and spectrum of brain abnormalities detected on conventional clinical MR imaging in fetuses with complex congenital heart disease and, second, to compare the congenital heart disease cohort with a control group of fetuses from healthy pregnancies. We prospectively recruited pregnant women with a confirmed fetal congenital heart disease diagnosis and healthy volunteers with normal fetal echocardiogram findings who underwent a fetal MR imaging between 18 and 39 weeks gestational age. A total of 338 fetuses (194 controls; 144 with congenital heart disease) were studied at a mean gestational age of 30.61 ± 4.67 weeks. Brain abnormalities were present in 23% of the congenital heart disease group compared with 1.5% in the control group (P < .001). The most common abnormalities in the congenital heart disease group were mild unilateral ventriculomegaly in 12/33 (36.4%) and increased extra-axial spaces in 10/33 (30.3%). Subgroup analyses comparing the type and frequency of brain abnormalities based on cardiac physiology did not reveal significant associations, suggesting that the brain abnormalities were not limited to those with the most severe congenital heart disease. This is the first large prospective study reporting conventional MR imaging findings in fetuses with congenital heart disease. Our results suggest that brain abnormalities are prevalent but relatively mild antenatally in fetuses with congenital heart disease. The long-term predictive value of these findings awaits further study.