Contrast-enhanced Magnetic Resonance Imaging Studies Research Articles

A novel hypothesis on cystic changes in pituitary adenomas and their association with a distinct local blood supply pattern

Pituitary adenoma, a common neuroendocrine tumor, commonly exhibits cystic changes as a distinct feature. Here we introduce and investigate a novel hypothesis suggesting a potential correlation between cystic pituitary adenomas and the unique local blood supply patterns of pituitary adenomas. As the tumor expands, compression of the superior vessels results in reduced blood supply from the superior hypophyseal artery, resulting in uneven distribution of the blood flow. Detailed analysis of clinical and surgical features of pituitary macroadenomas showed that cystic changes predominantly manifest in the upper part of the tumor and are driven by metabolic activity and relatively insufficient blood supply in this region. Supporting evidence from dynamic contrast-enhanced magnetic resonance imaging studies further substantiated this hypothesis. Overall, our findings offer a fresh perspective for early diagnosis and surgical decision-making for pituitary adenomas, contributing valuable information for individualized treatment and an improved prognosis. Despite some potential limitations, this hypothesis provides crucial insights into the understanding and management of pituitary adenomas.

A comparative study between the diagnostic performance of contrast-enhanced digital mammography and dynamic contrast-enhanced MRI in invasive lobular carcinoma of the breast

BackgroundInvasive lobular carcinoma is the second most prevalent histological subtype of breast cancer after invasive duct carcinoma, with a reported increased incidence in the last two decades. It often presents with challenging imaging characteristics that lower the sensitivity of mammography in their detection and delineation of their extent. Moreover, an increased risk of having synchronous lesions in the same or opposite breast was reported in cases with invasive lobular carcinoma. This obviates the need for other imaging modalities, specifically contrast-enhanced imaging modalities, to improve early detection as well as allow precise determination of the extent of the disease. Our aim in this study was to compare the diagnostic performance of contrast-enhanced digital mammography and dynamic contrast-enhanced magnetic resonance imaging (MRI) in the local staging of invasive lobular carcinoma regarding the size, extensions, multiplicity and bilaterality.MethodsThis study included 46 female patients with pathologically proven invasive lobular carcinoma. They underwent full-field digital mammography with a complementary ultrasound examination, contrast-enhanced digital mammography, and dynamic contrast-enhanced MRI. The findings encountered by the three imaging modalities were evaluated independently, and the results were compared with final histopathology.ResultsIn the current study, dynamic contrast-enhanced MRI study was the most sensitive modality in the detection of the index lesion, synchronous ipsilateral and contralateral lesions and achieved a sensitivity of 100% in each analysis as compared to contrast-enhanced digital mammography, which achieved a sensitivity of 97.8%, 85.7% and 80%, respectively. Regarding the assessment of the lesion extent to the surroundings, there was a tendency to overestimation by MRI examination.ConclusionsAlthough dynamic contrast-enhanced MRI is the most sensitive imaging modality for detecting the index lesion, multiplicity and bilaterality, contrast-enhanced digital mammography achieved comparable overall accuracy. Regarding the locoregional staging of invasive lobular carcinoma, there was a tendency for relative overestimation by MRI examination.

Can the Gleason score be predicted in patients with prostate cancer? A dynamic contrast-enhanced MRI, (68)Ga-PSMA PET/CT, PSA, and PSA-density comparison study.

The present study aims to evaluate whether perfusion parameters in prostate magnetic resonance imaging (MRI), (68)Ga-prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT), prostate-specific antigen (PSA), and PSA density can be used to predict the lesion grade in patients with prostate cancer (PCa). The study included a total of 137 PCa cases in which 12-quadrant transrectal ultrasound-guided prostate biopsy (TRUSBx) was performed, the Gleason score (GS) was determined, and pre-biopsy multiparametric prostate MRI and (68)Ga-PSMA PET/CT examinations were undertaken. The patient population was evaluated in three groups according to the GS: (1) low risk; (2) intermediate risk; (3) high risk. The PSA, PSA density, pre-TRUSBx (68)Ga-PSMA PET/CT maximum standardized uptake value (SUVmax), perfusion MRI parameters [maximum enhancement, maximum relative enhancement, T0 (s), time to peak (s), wash-in rate (s-1), and wash-out rate (s-1)] were retrospectively evaluated. There was no significant difference between the three groups in relation to the PSA, PSA density, and (68)Ga-PSMA PET/CT SUVmax (P > 0.05). However, the values of maximum enhancement, maximum relative enhancement (%), T0 (s), time to peak (s), wash-in rate (s-1), and wash-out rate (s-1) significantly differed among the groups. A moderate positive correlation was found among the prostate volume, PSA (r = 0.490), and (68)Ga-PSMA SUVmax (r = 0.322) in the patients. The wash-out rate (s-1) and wash-in rate (s-1) had the best diagnostic test performance (area under the curve: 89.1% and 78.4%, respectively). No significant correlation was found between the (68)Ga-PSMA PET/CT SUVmax and the GS. The wash-out rate was more successful in estimating the pretreatment GS than the (68)Ga-PSMA PET/CT SUVmax.

Musculoskeletal involvement in systemic lupus erythematosus: a contrast-enhanced magnetic resonance imaging study in 107 subjects.

Joint involvement in SLE is the most frequent manifestation and shows a wide heterogeneity. It has not a valid classification and it is often underestimated. Subclinical inflammatory musculoskeletal involvement is not well known. We aim to describe the prevalence of joint and tendon involvement in hand and wrist of SLE patients, either with clinical arthritis, arthralgia or asymptomatic and compare it with healthy subjects using contrasted MRI. SLE patients fulfilling SLICC criteria were recruited and classified as follows: group (G) 1: hand/wrist arthritis, G2: hand/wrist arthralgia, G3: no hand/wrist symptoms. Jaccoud arthropathy, CCPa and RF positivity, hand OA or surgery were excluded. Healthy subjects (HS) were recruited as controls: G4. Contrasted MRI of non-dominant hand/wrist was performed. Images were evaluated following RAMRIS criteria extended to PIP, Tenosynovitis score for RA and peritendonitis from PsAMRIS. Groups were statistically compared. A total of 107 subjects were recruited (G1: 31, G2:31, G3:21, G4:24). Any lesion: SLE patients 74.7%, HS 41.67%; P 0.002. Synovitis: G1: 64.52%, G2: 51.61%, G3: 45%, G4: 20.83%; P 0.013. Erosions: G1: 29.03%; G2: 54.84%, G3: 47.62%; G4: 25%; P 0.066. Bone marrow oedema: G1: 29.03%, G2: 22.58%, G3: 19.05%, G4: 0.0%; P 0.046. Tenosynovitis: G1: 38.71%; G2: 25.81%, G3: 14.29%, G4: 0.0%; P 0.005. Peritendonitis: G1: 12.90%; G2: 3.23%, G3: 0.0%, G4: 0.0%; P 0.07. SLE patients have a high prevalence of inflammatory musculoskeletal alterations confirmed by contrasted MRI, even if asymptomatic. Not only tenosynovitis but peritendonitis is also present.

Branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs): an MRI-based radiomic model to determine the malignant degeneration potential.

Branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs) are the most common pancreatic cystic tumors and have a low risk of malignant transformation. Features able to early identify high-risk BD-IPMNs are lacking, and guidelines currently rely on the occurrence of worrisome features (WF) and high-risk stigmata (HRS). In our study, we aimed to use a magnetic resonance imaging (MRI) radiomic model to identify features linked to a higher risk of malignant degeneration, and whether these appear before the occurrence of WF and HRS. We retrospectively evaluated adult patients with a known BD-IPMN who had had at least two contrast-enhanced MRI studies at our center and a 24-month minimum follow-up time. MRI acquisition protocol for the two examinations included pre- and post-contrast phases and diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) map. Patients were divided into two groups according to the development of WF or HRS at the end of the follow-up (Group 0 = no WF or HRS; Group 1 = WF or HRS). We segmented the MRI images and quantitative features were extracted and compared between the two groups. Features that showed significant differences (SF) were then included in a LASSO regression method to build a radiomic-based predictive model. We included 50 patients: 31 in Group 0 and 19 in Group 1. No patients in this cohort developed HRS. At baseline, 47, 67, 38, and 68 SF were identified for pre-contrast T1-weighted (T1-W) sequence, post-contrast T1-W sequence, T2-weighted (T2- W) sequence, and ADC map, respectively. At the end of follow-up, we found 69, 78, 53, and 91 SF, respectively. The radiomic-based predictive model identified 16 SF: more particularly, 5 SF for pre-contrast T1-W sequence, 6 for post-contrast T1-W sequence, 3 for T2-W sequence, and 2 for ADC. We identified radiomic features that correlate significantly with WF in patients with BD-IPMNs undergoing contrast-enhanced MRI. Our MRI-based radiomic model can predict the occurrence of WF.

MRI-Based Demonstration of the Normal Glymphatic System in a Human Population: A Systematic Review

BackgroundThe glymphatic system has been described as one that facilitates the exchange between the cerebrospinal fluid (CSF) and interstitial fluid, and many recent studies have demonstrated glymphatic flow based on magnetic resonance imaging (MRI). We aim to systematically review the studies demonstrating a normal glymphatic flow in a human population using MRI and to propose a detailed glymphatic imaging protocol.MethodsWe searched the MEDLINE and EMBASE databases to identify studies with human participants involving MRI-based demonstrations of the normal glymphatic flow. We extracted data on the imaging sequence, imaging protocol, and the targeted anatomical structures on each study.ResultsAccording to contrast-enhanced MRI studies, peak enhancement was sequentially detected first in the CSF space, followed by the brain parenchyma, the meningeal lymphatic vessel (MLV), and, finally, the cervical lymph nodes, corresponding with glymphatic flow and explaining the drainage into the MLV. Non-contrast flow-sensitive MRI studies revealed similar glymphatic inflow from the CSF space to the brain parenchyma and efflux of exchanged fluid from the brain parenchyma to the MLV.ConclusionWe may recommend T1-weighted contrast-enhanced MRI for visualizing glymphatic flow. Our result can increase understanding of the glymphatic system and may lay the groundwork for establishing central nervous system fluid dynamic theories and developing standardized imaging protocols.

Effects of k-space orders on the time-intensity curves in dynamic contrast-enhanced magnetic resonance imaging of the breast based on simulation study

PurposeThis study aims to investigate the influence of time-intensity curves (TICs) on the shapes using a dynamic contrast-enhanced magnetic resonance imaging (MRI) study depending on the Cartesian and radial orders for benign and cancerous breast tumors. MethodsBased on kinetic curve parameters, the signal intensities of six concentration gradients comprising two benign and four cancer models were used. The study aimed to construct a dynamic simulated image by creating a digital phantom image according to the following steps: (1) creating a simple numerical phantom, (2) setting the signal intensity in the contrast area, (3) creating the k-space in each time phase, (4) extracting data from k-space in each time phase, (5) filling in the k-space and adding data to the k-space assembly, and (6) creating a magnitude image. The TICs of Cartesian (centric and sequential) and radial (full-length [RFL] and half-length [RHL]) orders were created and sigmoid curve fitting was performed to compare these curves. Maximum slope (MS, s−1), width of the response (WOR, s), and primary signal response (PSR) were then calculated. Phase encode steps were set for 512 and 256. ResultsMS was significantly decreased by radial order in the cancer model. No change was observed in WOR in Cartesian order, whereas RFL and RHL orders increased in the cancer models. PSR increased remarkably in the radial orders of cancer models.The difference in the fill slope in radial orders was remarkable when the TIC was steeper compared with when it was gentle, especially RHL. In WOR, both radial RFL and RHL were well matched except for the one benign model, and the shape of radial TIC was similar to sequential order as compared to centric order in 256 steps. ConclusionThe effects of Cartesian and radial orders on the patterns of TICs in a dynamic contrast-enhanced MRI study of benign and cancerous breast tumors were revealed. Interestingly, the TIC gradient of radial orders became gentler, particularly in the breast cancer MRI.

Diagnostic Yield of MRI for Sensorineural Hearing Loss - An Audit.

Contrast-enhanced magnetic resonance imaging (CEMRI) of the head is frequently employed in investigations of sensorineural hearing loss (SNHL). The yield of these studies is perceptibly low and seemingly at odds with the aims of wise resource allocation and risk reduction within the Canadian healthcare system. The purpose of our study was to audit the use and diagnostic yield of CEMRI for the clinical indication of SNHL in our institution and to identify characteristics that may be leveraged to improve yield and optimize resource utilization. The charts of 500 consecutive patients who underwent CEMRI of internal auditory canal for SNHL were categorized as cases with relevant positive findings on CEMRI and those without relevant findings. Demographics, presenting symptoms, interventions and responses, ordering physicians, and investigations performed prior to CEMRI testing were recorded. Chi-squared test and t-test were used to compare proportions and means, respectively. CEMRI studies revealed relevant findings in 20 (6.2%) of 324 subjects meeting the inclusion criteria. Pre-CEMRI testing beyond audiometry was conducted in 35% of those with relevant positive findings compared to 7.3% of those without (p < 0.001). Auditory brainstem response/vestibular-evoked myogenic potentials were abnormal in 35% of those with relevant CEMRI findings compared to 6.3% of those without (p < 0.001). CEMRI is a valuable tool for assessing potential causes of SNHL, but small diagnostic yield at present needs justification for contrast injection for this indication. Our findings suggest preferred referral from otolaryngologists exclusively, and implementation of a non-contrast MRI for SNHL may be a better diagnostic tool.

The Potentials and Role of Diffusion-Weighted Magnetic Resonance Imaging in Evaluating the Efficiency of Antitumor Treatment of Patients with Breast Liver Metastasis

Objective. To compare the informative value of using dynamic magnetic resonance imaging (MRI) and diffusion-weighted MRI (DW-MRI) in patients with breast liver metastasis during chemotherapy.Material and methods. The investigation enrolled 30 patients with breast liver metastasis during their treatment. The results of standard intravenous contrast-enhanced abdominal MRI studies (by evaluating the liver in the arterial, venous, and delayed phases) were compared with those of DW-MRI with different B-factor values (50, 400 and 800 sec/mm2).Results. Comparison of the findings of initial studies prior to chemotherapy (those of only dynamic intravenous contrast-enhanced MRI and only DW-MRI) revealed a complete correspondence with the number of detected foci in 10 patients. Ten patients had a larger number of metastatic foci at DW-MRI than at intravenous contrast-enhanced MRI, in the aggregate by 44 foci more (of them 36 foci measured less than 1 cm). The remaining 10 of the 30 patients were found to have multiple, unquantifiable (more than 20–40) metastatic foci of various sizes (1–6 cm) at both intravenous contrast-enhanced MRI and DW-MRI. Nineteen of the 30 patients were followed up during their chemotherapy. Seven of the 19 patients showed a stabilized liver metastatic process that was similarly evidenced by both techniques. Eleven of the 19 patients were observed to have a progressive metastatic process that was reflected by the similar increase in the number and size of metastases in 5 of the 11 patients, as shown by both of the above techniques. In the remaining 6 of the 11 patients, the number of newly detected liver tumors proved to be larger at DW-MRI than at intravenous contrast-enhanced MRI. Both techniques showed that the last patient of the 19 cases had a decrease in the number of small liver metastases that maintained their sizes (less than 1 cm).Conclusion. DW-MRI has been shown to be much more effective in detecting metastases than conventional intravenous contrast-enhanced MRI, which necessitates the inclusion of this technique in standard abdominal MRI protocols for patients with liver metastasis.

Independent validation of machine learning in diagnosing breast Cancer on magnetic resonance imaging within a single institution

BackgroundAs artificial intelligence methods for the diagnosis of disease advance, we aimed to evaluate machine learning in the predictive task of distinguishing between malignant and benign breast lesions on an independent clinical magnetic resonance imaging (MRI) dataset within a single institution for subsequent use as a computer aid for radiologists.MethodsComputer analysis was conducted on consecutive dynamic contrast-enhanced MRI (DCE-MRI) studies from 1483 breast cancer and 496 benign patients who underwent MRI examinations between February 2015 and October 2017; with the age ranges of the cancer and benign patients being 19 to 77 and 16 to 76 years old, respectively. Cases were separated into a training dataset (years 2015 & 2016; 1444 cases) and an independent testing dataset (year 2017; 535 cases) based solely on MRI examination date. After radiologist indication of the lesion, the computer automatically segmented and extracted radiomic features, which were subsequently merged with a support-vector machine (SVM) to yield a lesion signature. Area under the receiving operating characteristic (ROC) curve (AUC) with 95% confidence intervals (CI) served as the primary figure of merit in the statistical evaluation for this clinical classification task.ResultsIn the task of distinguishing malignant and benign breast lesions DCE-MRI, the trained predictive model yielded an AUC value of 0.89 (95% CI: 0.858, 0.922) on the independent image set. AUC values of 0.88 (95% CI: 0.845, 0.926) and 0.90 (95% CI: 0.837, 0.940) were obtained for mass lesions only and non-mass lesions only, respectively. Compared with actual clinical management decisions, the predictive model achieved 99.5% sensitivity with 9.6% fewer recommended biopsies.ConclusionOn an independent, consecutive clinical dataset within a single institution, a trained machine learning system yielded promising performance in distinguishing between malignant and benign breast lesions.

Symptomatic Carotid Plaques Demonstrate Less Leaky Plaque Microvasculature Compared With the Contralateral Side: A Dynamic Contrast-Enhanced Magnetic Resonance Imaging Study.

BackgroundRupture of a vulnerable carotid atherosclerotic plaque is an important underlying cause of ischemic stroke. Increased leaky plaque microvasculature may contribute to plaque vulnerability. These immature microvessels may facilitate entrance of inflammatory cells into the plaque. The objective of the present study is to investigate whether there is a difference in plaque microvasculature (the volume transfer coefficient K trans) between the ipsilateral symptomatic and contralateral asymptomatic carotid plaque using noninvasive dynamic contrast‐enhanced magnetic resonance imaging.Methods and ResultsEighty‐eight patients with recent transient ischemic attack or ischemic stroke and ipsilateral >2 mm carotid plaque underwent 3 T magnetic resonance imaging to identify plaque components and to determine characteristics of plaque microvasculature. The volume transfer coefficient K trans, indicative for microvascular density, flow, and permeability, was calculated for the ipsilateral and asymptomatic plaque, using a pharmacokinetic model (Patlak). Presence of a lipid‐rich necrotic core, intraplaque hemorrhage, and a thin and/or ruptured fibrous cap was assessed on multisequence magnetic resonance imaging. We found significantly lower K trans in the symptomatic carotid plaque compared with the asymptomatic side (0.057±0.002 min−1 versus 0.062±0.002 min−1; P=0.033). There was an increased number of slices with intraplaque hemorrhage (0.9±1.6 versus 0.3±0.8, P=0.002) and lipid‐rich necrotic core (1.4±1.9 versus 0.8±1.4, P=0.016) and a higher prevalence of plaques with a thin and/or ruptured fibrous cap (32% versus 17%, P=0.023) at the symptomatic side.Conclusions K trans was significantly lower in symptomatic carotid plaques, indicative for a decrease of plaque microvasculature in symptomatic plaques. This could be related to a larger amount of necrotic tissue in symptomatic plaques.Clinical Trial Registration URL: http://www.clinicaltrials.gov.uk. Unique identifier: NCT01208025.

Gadolinium Enhancement May Indicate a Condition at Risk of Developing Necrosis in Marchiafava-Bignami Disease: A Case Report and Literature Review.

Marchiafava–Bignami disease (MBD) is a rare condition characterized by demyelination, necrosis and atrophy of the corpus callosum (CC), and mainly associated with alcoholism. MBD may present with various clinical manifestations. Brain magnetic resonance imaging (MRI) scan is important in prompt diagnosis and treatment of MBD. Here we reported a case of MBD and reviewed literature about the usage of gadolinium-enhanced MRI in MBD. Gadolinium enhancement may indicate a condition at risk of developing necrosis. We therefore recommend a contrast-enhanced MRI study in severe alcoholics with suspected diagnosis of MBD.

CEUS-Diagnostic of malignant liver lesions

Cross-sectional modalities or conventional ultrasound are not always able to sufficiently identify and characterize malignant liver lesions. The evaluation of malignant liver lesions in conventional ultrasound relies on echostructure, shape and borders, but often warrants additional contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) studies. Contrast-enhanced ultrasound (CEUS) is arelatively safe imaging technique used for the detection and characterization of malignant liver lesions. The use of asecond-generation contrast agent in dynamic real-time imaging allows the visualization of vascularization in any kind of liver lesion as well as liver perfusion during the arterial, portal venous and late phase. Due to the different enhancement patterns, it is possible to differentiate aliver lesion with high diagnostic accuracy (over 90%). CEUS is ahelpful complementary technique to cross-sectional imaging for the evaluation of unclear liver lesions and may frequently obviate additional contrast-enhanced MRI or CT studies. CEUS enables the detection and characterization of liver lesions in real time.

The use of porous tantalum cages in the treatment of unremitting spondylodiscitis: a case report

Background: Unsuccessful medical treatment of pyogenic multifocal spondylodiscitis including signs of sepsis and unremitting pain is challenging. The aim of our report was to present a case of multilevel spondylodiscitis successfully treated by posterior lumbar interbody fusion using porous tantalum cages.Case presentation: A 59-year-old male was diagnosed with spondylodiscitis at T8-T9 level. Although treated with antibiotics, the patient again presented with worsening of systemic signs of infection and back pain. Contrast-enhanced magnetic resonance imaging studies revealed spondylodiscitis at L1 to S1 level. Posterior lumbar interbody bone fusion with tantalum cages from L1 to S1 was performed. The inflammation rapidly subsided. Computer tomography studies showed a stable construct at 24 months.Conclusion: Porous tantalum cages used in combination with transpedicular fixation seem to be a sound alternative to interbody devices made from other materials when treating spondylodiscitis cases without definite osseous destruction.

Diagnostic performance of magnetic resonance imaging and 3D endoanal ultrasound in detection, staging and assessment post treatment, in anal cancer.

We compared Magnetic Resonance Imaging (MRI) and 3D Endoanal Ultrasound (EAUS) imaging performance to confirm anal carcinoma and to monitor treatment response.58 patients with anal cancer were retrospectively enrolled. All patients underwent clinical examination, anoscopic examination; EAUS and contrast-enhanced MRI study before and after treatment. Four radiologists evaluated the presence of lesions, using a 4-point confidence scale, features of the lesion and nodes on EAUS images, T1-weighted (T1-W), T2-weighted (T2-W) and diffusion-weighted images (DWI) signal intensity (SI), the apparent diffusion coefficient (ADC) map for nodes and lesion, as well as enhancement pattern during dynamic MRI were assessed.All lesions were detected by EAUS while MRI detected 93.1% of anal cancer. MRI showed a good correlation with EAUS, anoscopy and clinical examination. The residual tissue not showed significant difference in EAUS assessment and T2-W SI in pre and post treatment. We found significant difference in dynamic study, in SI of DWI, in ADC map and values among responder's patients in pre and post treatment. The neoplastic nodes were hypoecoic on EAUS, with hyperintense signal on T2-W sequences and hypointense signal on T1-W. The neoplastic nodes showed SI on DWI sequences and ADC value similar to anal cancer. We found significant difference in nodes status in pre and post therapy on DWI data.3D EAUS and MRI are accurate techniques in anal cancer staging, although EAUS is more accurate than MRI for T1 stage. MRI allows correct detection of neoplastic nodes and can properly stratify patients into responders or non responders.

Intra-individual comparison of CAIPIRINHA VIBE technique with conventional VIBE sequences in contrast-enhanced MRI of focal liver lesions

PurposeTo evaluate the impact of controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) volume interpolated breath-hold examination (VIBE) magnetic resonance imaging (MRI) technique on image quality, reader confidence, and inter-observer agreement for the assessment of focal liver lesions in comparison with the standard VIBE approach. Material and methodsIn this IRB-approved intra-individual comparison study, abdominal arterial and portal-venous contrast-enhanced MRI studies were retrospectively analyzed in 38 patients with malignant liver lesions. Each patient underwent both CAIPIRINHA and conventional VIBE 3T MRI within 3 months, showing stable disease. Images were evaluated using 5-point rating scales by two blinded radiologists with more than 20 and 5 years of experience in MRI, respectively. Readers scored dignity of liver lesions and assessed which liver segments were affected by malignancy (ranging from 1=definitely benign/not affected to 5=definitely malignant/affected by malignancy). Readers also rated overall image quality, sharpness of intrahepatic veins, and diagnostic confidence (ranging from 1=poor to 5=excellent). ResultsReviewers achieved a higher inter-observer reliability using CAIPIRINHA when they reported which liver segments were affected by malignancy compared to traditional VIBE series (κ=0.62 and 0.54, respectively, p<0.05). Similarly, CAIPIRINHA showed a slightly higher inter-rater agreement for the dignity of focal liver lesions versus the standard VIBE images (κ=0.50 and 0.49, respectively, p<0.05). CAIPIRINHA series also scored higher in comparison to standard VIBE sequences (mean scores: image quality, 4.2 and 3.5; sharpness of intrahepatic vessels, 3.8 and 3.2, respectively, p<0.05) for both reviewers and allowed for higher subjective diagnostic confidence (ratings, 3.8 and 3.2, respectively, p<0.05). ConclusionCompared to the standard VIBE approach, CAIPIRINHA VIBE technique provides improved image quality and sharpness of intrahepatic veins, as well as higher diagnostic confidence. Additionally, this technique allows for higher inter-observer agreement when reporting focal liver lesions for both dignity and allocation.

Reduction of Longitudinal Vertebral Blood Perfusion and Its Likely Causes: A Quantitative Dynamic Contrast-enhanced MR Imaging Study of a Rat Osteoporosis Model.

Purpose To determine the longitudinal relationships among lumbar vertebral blood perfusion, bone mass, and marrow adipose tissue in a rat osteoporosis model after ovariectomy by using quantitative dynamic contrast agent-enhanced (DCE) magnetic resonance (MR) imaging, microcomputed tomography (micro-CT), and proton MR spectroscopy. Materials and Methods In this animal review committee-approved study, lumbar vertebrae were evaluated through MR spectroscopy, quantitative DCE MR imaging, micro-CT, and histopathologic analysis, and blood was examined at 0, 2, 6, 10, 14, 18, and 24 weeks after ovariectomy consisting of exposure of the ovaries but no excision (n = 35) or sham operation, defined as exposure of the ovaries but no excision (n = 35). Differences in the parameters of these examinations between two groups at the same time point were analyzed by an independent-sample t test. Results Significantly reduced volume transfer constant (Ktrans) and volume of extravascular extracellular space per unit volume of tissue (week 2 and 10, respectively; P = .036 and P = .014, respectively), decreased bone mineral density (week 2; P = .014), and increased fat fraction (week 6; P = .036) in the ovariectomy group were observed, compared with those in the sham group. Vascular endothelial growth factor and microvessel density values of the ovariectomy group decreased significantly compared with those of the sham group from weeks 18 (P = .005) and 14 (P = .018), respectively. Transmission electron microscopy revealed tighter gaps among vascular endothelial cells and more marrow fibrosis in the ovariectomy group. Conclusion Quantitative DCE MR imaging can directly reflect marrow perfusion. Ktrans is a promising parameter to demonstrate early reduced marrow perfusion. Enhanced vasoconstriction and tightened gaps among vascular endothelial cells may be the likely causes in the initial stage of osteoporosis. Increased marrow adipose tissue, decreased microvessel density, and increased marrow fibrosis may aggravate marrow ischemia in the late stage of osteoporosis. © RSNA, 2016 Online supplemental material is available for this article.

Abstract 2710: Model evolution technique as a novel concept for characterization of tumor heterogeneity in dynamic contrast enhanced MRI studies

Abstract Introduction: Many studies have shown that tumor vascular network and the assortment of tumorous cells inside and on the periphery of solid tumors are spatially heterogeneous. Variation in cell packing density (VCPD), hypoxia, acidosis, and elevated interstitial fluid pressure (IFP) are main characteristic features of solid tumors. Elevated IFP and VCPD in solid tumors can be generally relevant to the pathological structures at the cellular level that is fundamental to understanding the chance of response to treatment and recurrence. Therefore, non-invasive quantification of tumor heterogeneity for the same types of tumors can play an important role in diagnosis and treatment planning. Hypothesis: In this pilot study, using Nested Model (NM) selection technique, Model Evolution (ME) concept is framed and introduced to quantify the evolutions of 3 different physiologically NM that are derived from standard Tofts model, throughout the course of Dynamic Contrast Enhanced (DCE) Magnetic Resonance Imaging (MRI) experiment. Using ME technique for pharmacokinetic (PK) modeling and DCE-MRI data analysis, a heterogeneity measure is formulated and introduced based on the evolutionary profile of the estimated extra-cellular extra-vascular (ve) volume. We hypothesized that the ME profiles in the course of DCE-MRI experiment, highly depend on the inward diffusion and outward convection of contrast agent concentration and contain abundant information for describing the compartmentalization and heterogeneity levels of solid tumors. Material and Methods: 24 athymic Nude rats with U251n rat tumor model of cerebral tumor were studied. Look-Locker T1 mapping and DCE-MRI experiments (Dual Gradient Echo, 150 image sets at 4.0 sec intervals over 10 min: matrix = 128×64, five 2.0 mm slices, NE = 2, NA = 1, TE/TE/TR = 2.0/4.0/40ms with bolus intravenous injection of the Magnevist at 0.25 mmol/kg) acquired at 7T field strengths. In each animal, in-vivo measurement of tumor IFP was done right after the DCE-MRI experiment using a wick-in-needle technique. The ME technique was applied on DCE-MR data of 24 U251n rat tumors to characterize the heterogeneity of each tumor and then the results were compared to their known in vivo measure of IFPs. Results and Conclusions: Results of this pilot study clearly attest that the evolutionary profile of ve can be used to characterize the heterogeneity level of solid tumors. The ME results imply that as the slop of the evolutionary profile increases, the IFP of tumor increases. Also, the latency of the profile during the course of MR experiment can reliably explain the tumor compartmentalization and their elevated IFP. This pilot study confirms that the ME concept can make a paradigm shift in non-invasive quantification of tumor heterogeneity from DCE-MRI studies Citation Format: Hassan Bagher-Ebadian, Azimeh NV Dehkordi, Rasha Alamgharibi, David Nathanson, Hamid Soltanian-Zadeh, Arbab S. Ali, Stephen Brown, Meser M. Ali, Tom Mikkelsen, James R. Ewing. Model evolution technique as a novel concept for characterization of tumor heterogeneity in dynamic contrast enhanced MRI studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2710.

Safety and Clinical Outcomes of Percutaneous Radiofrequency Ablation for Intermediate and Large Bone Tumors Using a Multiple-Electrode Switching System: A Phase II Clinical Study

PurposeTo evaluate the safety and clinical outcomes of radiofrequency (RF) ablation using a multiple-electrode switching system in patients with bone tumors > 3 cm. Materials and MethodsThis prospective study enrolled 20 subjects (15 men, 5 women; mean age 70.0 y ± 7.4 [SD]; range, 60–80 y) with malignant unresectable bone tumors. The maximum mean tumor diameter was 5.5 cm ± 2.0 (range, 3.1–10.0 cm). Two to three RF electrodes were placed into each bone tumor. Real-time CT fluoroscopic guidance was used with a multiple-electrode switching system. The primary endpoint was safety, as evaluated by Common Terminology Criteria for Adverse Events, until 12 months after bone RF ablation. As secondary endpoints, pain relief was evaluated by visual analog scale (VAS) scores before and 1 week after RF ablation; tumor response, by contrast-enhanced magnetic resonance imaging studies until 4 weeks after bone RF ablation; and survival, by Kaplan-Meier method. ResultsNo adverse event was found in 19 of 20 patients (95%). Grade 2 fever occurred in 1 patient (5%; 1/20). VAS scores decreased by ≥ 2 in 11 of 13 patients (84.6%) who had painful bone tumors. Tumor response (complete or partial response) was achieved in 16 of 18 patients (88.9%) who underwent follow-up imaging studies. The 1-year overall survival rate was 60.9%, and the median survival time was 14.1 months. ConclusionsBone RF ablation using this system is safe and achieves local tumor control and pain relief in patients with large bone tumors.

GW26-e3961 Correlation between the degree of plaque inflammation and adventitial perfusion in the carotid artery: a combined 18F-fluorodeoxyglucose positron-emission tomography and dynamic contrast-enhanced magnetic resonance imaging study

GW26-e3961 Correlation between the degree of plaque inflammation and adventitial perfusion in the carotid artery: a combined 18F-fluorodeoxyglucose positron-emission tomography and dynamic contrast-enhanced magnetic resonance imaging study