Magnetic Resonance Positron Emission Tomography Research Articles

Hybrid cardiac PET/MR: the value of multiparametric assessment in cardiac sarcoidosis

Purpose The advent of hybrid positron emission tomography/magnetic resonance (PET/MR) systems has opened the gate to integrated multiparametric evaluation of patients with suspected cardiac sarcoidosis. The aim of the present paper is to systematically review all available literature to define the role of hybrid PET/MR in patients with confirmed or suspected cardiac sarcoidosis.

A human brain tau PET template in MNI space for the voxel-wise analysis of Alzheimer’s disease

BackgroundPositron emission tomography (PET) imaging techniques of tau retention in the human brain are important for mechanistic studies of Alzheimer's disease (AD). However, the method for effectively conducting voxel-wise analysis on tau PET images still needs to be improved. In the present study, we introduced a tau PET template for the human brain in Montreal Neurological Institute (MNI) space for the convenient and reliable voxel-wise analysis of tau PET images in AD studies. New methodTwenty-four AD patients and 22 controls were used to construct the tau PET template, and an additional 22 subjects (11 AD patients and 11 controls) were enrolled to evaluate the performance of the template. Thirty regions (28 cortical and 2 subcortical regions) throughout the brain were used to evaluate the accuracy of the tau PET template. ResultsA significant relationship (R2 = 0.848, P < 0.001) was found between the standardized uptake value ratios (SUVRs) obtained by the tau PET template and magnetic resonance imaging (MRI)-aided approach, and the paired-sample t-test showed no significant difference (P = 0.62) between the values. These two approaches revealed consistent brain regions with high tau retention. Comparison with existing methodsThe tau PET template was comparable with the traditional MRI-aided strategy. Furthermore, compared to the MRI-aided approach, the tau PET template was more convenient and easier to use. More importantly, in most clinical settings, AD patients who underwent PET/computed tomography (CT) typically do not have MR images, in which case the traditional MRI-aided approach would not be applicable. Our tau PET template overcame this deficiency and may serve as a useful tool in AD research. ConclusionsThis tau PET template performed well and may serve as a useful tool in future AD studies.

Nieuwe beeldvormende technieken bij de diagnostiek van het prostaatcarcinoom

Samenvatting In dit artikel worden beeldvormende technieken besproken die worden gebruikt bij de diagnostiek van prostaatkanker en worden toekomstige ontwikkelingen op dit terrein belicht. Nieuwe en op dit moment bij voorkeur gebruikte beeldvormende technieken (prostaatspecifiek membraanantigeen (PSMA), positronemissietomografie met computertomografie (PET/CT) en whole-body magnetic resonance imaging (MRI)) met diffusiegewogen opname, detecteren metastasen die met de traditionele technieken (botscan en computertomografie (CT)) onopgemerkt zouden zijn gebleven. Gegevens over de daadwerkelijk klinische functionaliteit van deze nieuwe technieken ontbreken echter nog. Dit leidt tot praktische dilemma’s bij de behandeling van patiënten met prostaatkanker, omdat de resultaten van grote klinische studies zijn gebaseerd op oude beeldvormende technieken. Deze dilemma’s kunnen pas worden opgelost als de diagnostische accuratesse van de nieuwe beeldvormende technieken, en de klinische consequenties van vroege detectie van metastasen, bekend zijn.

Simultaneous 13N-Ammonia and gadolinium first-pass myocardial perfusion with quantitative hybrid PET-MR imaging: a phantom and clinical feasibility study

BackgroundPositron emission tomography (PET) is the non-invasive reference standard for myocardial blood flow (MBF) quantification. Hybrid PET-MR allows simultaneous PET and cardiac magnetic resonance (CMR) acquisition under identical experimental and physiological conditions. This study aimed to determine feasibility of simultaneous 13N-Ammonia PET and dynamic contrast-enhanced CMR MBF quantification in phantoms and healthy volunteers.MethodsImages were acquired using a 3T hybrid PET-MR scanner. Phantom study: MBF was simulated at different physiological perfusion rates and a protocol for simultaneous PET-MR perfusion imaging was developed. Volunteer study: five healthy volunteers underwent adenosine stress. 13N-Ammonia and gadolinium were administered simultaneously. PET list mode data was reconstructed using ordered subset expectation maximisation. CMR MBF was quantified using Fermi function-constrained deconvolution of arterial input function and myocardial signal. PET MBF was obtained using a one-tissue compartment model and image-derived input function.ResultsPhantom study: PET and CMR MBF measurements demonstrated high repeatability with intraclass coefficients 0.98 and 0.99, respectively. There was high correlation between PET and CMR MBF (r = 0.98, p < 0.001) and good agreement (bias − 0.85 mL/g/min; 95% limits of agreement 0.29 to − 1.98). Volunteer study: Mean global stress MBF for CMR and PET were 2.58 ± 0.11 and 2.60 ± 0.47 mL/g/min respectively. On a per territory basis, there was moderate correlation (r = 0.63, p = 0.03) and agreement (bias − 0.34 mL/g/min; 95% limits of agreement 0.49 to − 1.18).ConclusionSimultaneous MBF quantification using hybrid PET-MR imaging is feasible with high test repeatability and good to moderate agreement between PET and CMR. Future studies in coronary artery disease patients may allow cross-validation of techniques.

Assessment of myocardial viability by PET.

Viability assessment has a key role in the management of patients with ischemic heart disease. Positron emission tomography (PET) is a unique modality that evaluates myocardial viability via assessing the tissues metabolic and perfusion properties. The mainstay of metabolic imaging relies on glucose metabolism using fluorodeoxyglucose, a radiolabeled glucose analog. Mismatch in perfusion metabolism data denotes hibernating myocardium with a high likelihood of functional recovery following revascularization. Matched absence or reduction in perfusion metabolism data represents scar with a low likelihood of functional recovery following revascularization. This review will focus on PET radiotracers and techniques used to assess myocardial viability. Single-center studies have shown that patients with PET mismatch undergoing bypass grafting had improved survival compared with those on medical therapy. In addition to survival benefit, the patients who underwent PET-guided revascularization had significant improvement in angina and heart failure symptomology. Recent technological advancements in the field of PET-magnetic resonance (MR) opens a new frontier in the field of advanced imaging as it combines anatomical, functional, tissue characterization, and metabolic perfusion data obtained in one setting. The incremental value of PET/MRI is best established in diagnosing and monitoring disease activity in patients with cardiac sarcoidosis and occult malignancies, but more studies are needed to assess it value in viability assessment. In conclusion, imaging myocardial viability by PET provides assessment of both physiological perfusion and myocardial tissue's metabolic activity to differentiate hibernating from scarred myocardium.

Positron-emission tomography for hepatocellular carcinoma: Current status and future prospects

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer mortality worldwide. Various imaging modalities provide important information about HCC for its clinical management. Since positron-emission tomography (PET) or PET-computed tomography was introduced to the oncologic setting, it has played crucial roles in detecting, distinguishing, accurately staging, and evaluating local, residual, and recurrent HCC. PET imaging visualizes tissue metabolic information that is closely associated with treatment. Dynamic PET imaging and dual-tracer have emerged as complementary techniques that aid in various aspects of HCC diagnosis. The advent of new radiotracers and the development of immuno-PET and PET-magnetic resonance imaging have improved the ability to detect lesions and have made great progress in treatment surveillance. The current PET diagnostic capabilities for HCC and the supplementary techniques are reviewed herein.

Medullary Thyroid Carcinoma: An Update on Imaging.

Medullary thyroid carcinoma (MTC), arising from the parafollicular C cells of the thyroid, accounts for 1–2% of thyroid cancers. MTC is frequently aggressive and metastasizes to cervical and mediastinal lymph nodes, lungs, liver, and bones. Although a number of new imaging modalities for directing the management of oncologic patients evolved over the last two decades, the clinical application of these novel techniques is limited in MTC. In this article, we review the biology and molecular aspects of MTC as an important background for the use of current imaging modalities and approaches for this tumor. We discuss the modern and currently available imaging techniques—advanced magnetic resonance imaging (MRI)-based techniques such as whole-body MRI, dynamic contrast-enhanced (DCE) technique, diffusion-weighted imaging (DWI), positron emission tomography/computed tomography (PET/CT) with 18F-FDOPA and 18F-FDG, and integrated positron emission tomography/magnetic resonance (PET/MR) hybrid imaging—for primary as well as metastatic MTC tumor, including its metastatic spread to lymph nodes and the most common sites of distant metastases: lungs, liver, and bones.

How Effective Are Noninvasive Tests for Diagnosing Malignant Peripheral Nerve Sheath Tumors in Patients with Neurofibromatosis Type 1? Diagnosing MPNST in NF1 Patients.

Background Distinguishing between benign and malignant peripheral nerve sheath tumors (MPNSTs) in neurofibromatosis 1 (NF1) patients prior to excision can be challenging. How can MPNST be most accurately diagnosed using clinical symptoms, magnetic resonance imaging (MRI) findings (tumor size, depth, and necrosis), positron emission tomography (PET) measures (SUVpeak, SUVmax, SUVmax tumor/SUVmean liver, and qualitative scale), and combinations of the above? Methods. All NF1 patients who underwent PET imaging at our institution (January 1, 2007–December 31, 2016) were included. Medical records were reviewed for clinical findings; MR images and PET images were interpreted by two fellowship-trained musculoskeletal and nuclear medicine radiologists, respectively. Receiver operating characteristic (ROC) curves were created for each PET measurement; the area under the curve (AUC) and thresholds for diagnosing malignancy were calculated. Logistic regression determined significant predictors of malignancy. Results Our population of 41 patients contained 34 benign and 36 malignant tumors. Clinical findings did not reliably predict MPNST. Tumor depth below fascia was highly sensitive; larger tumors were more likely to be malignant but without a useful cutoff for diagnosis. Necrosis on MRI was highly accurate and was the only significant variable in the regression model. PET measures were highly accurate, with AUCs comparable and cutoff points consistent with prior studies. A diagnostic algorithm was created using MRI and PET findings. Conclusions MRI and PET were more effective at diagnosing MPNST than clinical features. We created an algorithm for preoperative evaluation of peripheral nerve sheath tumors in NF1 patients, for which additional validation will be indicated.

Circulating miRNAs in Untreated Breast Cancer: An Exploratory Multimodality Morpho-Functional Study.

The aim of this study was to identify new disease-related circulating miRNAs with high diagnostic accuracy for breast cancer (BC) and to correlate their deregulation with the morpho-functional characteristics of the tumour, as assessed in vivo by positron emission tomography/magnetic resonance (PET/MR) imaging. A total of 77 untreated female BC patients underwent same-day PET/MR and blood collection, and 78 healthy donors were recruited as negative controls. The expression profile of 84 human miRNAs was screened by using miRNA PCR arrays and validated by real-time PCR. The validated miRNAs were correlated with the quantitative imaging parameters extracted from the primary BC samples. Circulating miR-125b-5p and miR-143-3p were upregulated in BC plasma and able to discriminate BC patients from healthy subjects (miR-125-5p area under the receiver operating characteristic ROC curve (AUC) = 0.85 and miR-143-3p AUC = 0.80). Circulating CA15-3, a soluble form of the transmembrane glycoprotein Mucin 1 (MUC-1) that is upregulated in epithelial cancer cells of different origins, was combined with miR-125b-5p and improved the diagnostic accuracy from 70% (CA15-3 alone) to 89% (CA15-3 plus miR-125b-5p). MiR-143-3p showed a strong and significant correlation with the stage of the disease, apparent diffusion coefficient (ADCmean), reverse efflux volume transfer constant (Kepmean) and maximum standardized uptake value (SUVmax), and it might represent a biomarker of tumour aggressiveness. Similarly, miR-125b-5p was correlated with stage and grade 2 but inversely correlated with the forward volume transfer constant (Ktransmean) and proliferation index (Ki67), suggesting a potential role as a biomarker of a relatively more favourable prognosis. In situ hybridization (ISH) experiments revealed that miR-143-3p was expressed in endothelial tumour cells, miR-125-5p in cancer-associated fibroblasts, and neither in epithelial tumour cells. Our results suggested that miR-125-5p and miR-143-3p are potential biomarkers for the risk stratification of BC, and Kaplan-Maier plots confirmed this hypothesis. In addition, the combined use of miR-125-b-5p and CA15-3 enhanced the diagnostic accuracy up to 89%. This is the first study that correlates circulating miRNAs with in vivo quantified tumour biology through PET/MR biomarkers. This integration elucidates the link between the plasmatic increase in these two potential circulating biomarkers and the biology of untreated BC. In conclusion, while miR-143-3b and miR-125b-5p provide valuable information for prognosis, a combination of miR-125b-5p with the tumour marker CA15-3 improves sensitivity for BC detection, which warrants consideration by further validation studies.

Cervical cancer evaluated with integrated 18F-FDG PET/MR.

The current study aimed to evaluate the correlation between maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin) of cervical cancer using an integrated 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance (PET/MR) imaging system, and to determine the association with pathological prognostic factors. A total of 46 patients were pathologically diagnosed with cervical cancer and underwent PET/MR prior to surgery, including total hysterectomy, bilateral pelvic lymph node dissection or paraaortic lymph node dissection. The imaging biomarkers included the SUVmax and ADCmin. The pathological prognostic factors were as follows: Tumor size, histological grade, International Federation of Gynecology and Obstetrics (FIGO) stage and lymph node metastasis. Pearson's correlation analysis was used to evaluate the correlation between imaging biomarkers and the tumor size and the Mann-Whitney U test analysis was used to evaluate the association between imaging biomarkers and pathological factors. The mean SUVmax was 11.1±8.7 (range, 3.16–51.6) and the mean ADCmin was 0.76±0.15×10−3 mm2/s (range, 0.47–1.04×10−3 mm2/s). The SUVmax had a significant negative correlation with the ADCmin (r=−0.700; P<0.001). The SUVmax was significantly increased in patients with poorly differentiated tumors (P=0.001), patients with FIGO stage IIB (P=0.005) and the patients with lymph node metastasis (P=0.040). The ADCmin was significantly decreased in patients with poorly differentiated tumors (P<0.001) and patients with FIGO stage IIB (P=0.017). Statistical analysis revealed no significant correlation between the tumor size and the SUVmax (r=0.286;P=0.054), or between the tumor size and the ADCmin (r=−0.231; P=0.122). Area under the curve (AUC) analysis revealed that SUVmax had a higher diagnostic value for lymph node metastasis (AUC=0.681) and FIGO staging (AUC=0.837) compared with ADCmin, whereas ADCmin had a higher diagnostic value for the grade of pathological differentiation (AUC=0.816) compared with SUVmax (AUC=0.788). The results of the current study demonstrated that there was a significant negative correlation between SUVmax and ADCmin, which were associated with prognostic factors.

The Influence of Magnetic Fields (0.05 T ≤ B ≤ 7 T) on the Response of Personal Thermoluminescent Dosimeters to Ionizing Radiation

We investigated the main question of whether thermoluminescent dosimeters indicate the correct dose when exposed to magnetic fields from low stray fields up to high magnetic resonance imaging fields inside human magnetic resonance imaging scanners (0.05 T ≤ B ≤ 7 T) during and after irradiation. Medical personnel working in radiology, oncology, or nuclear medicine are regularly monitored with thermoluminescent dosimeters. They might also enter the magnetic field of a magnetic resonance imaging scanner while supervising patients as well as during positron emission tomography-magnetic resonance imaging and magnetic resonance imaging-linac integrated imaging systems and will therefore be exposed to the magnetic fields of magnetic resonance imaging scanners and low stray fields of several millitesla outside of the magnetic resonance imaging scanner, not only before and after, but also during irradiation. Panasonic thermoluminescent dosimetry badges and ring dosimeters for personal monitoring were exposed to magnetic fields originating from a 7 T and a 3 T magnetic resonance imaging scanner as well as neodymium permanent magnets. Four different sealed Cs sources were used in two sets of experiments: (1) magnetically induced fading: irradiated thermoluminescent dosimeters (D ≈ 100 mSv) were exposed to a strong magnetic field (B = 7 T) of a human high-field magnetic resonance imaging scanner after irradiation; no magnetically induced fading (magnetoluminescence) for LiBO:Cu or CaSO:Tm was observed; (2) magnetically induced attenuation: thermoluminescent dosimeters were placed during irradiation in a magnetic field for about 60 h; a significantly reduced dose response was observed for LiBO:Cu-interestingly not at maximum B ≈ 7 T but at B ≈ 0.2 T. This experimental observation is possibly relevant especially for medical and technical personnel in nuclear medicine before and during a magnetic resonance imaging scanning procedure. Follow-up studies need to be made to clarify the kinetics of this effect.

Pilot study of [18F] fluorodexoyglucose positron emission tomography-magnetic resonance imaging (FDG-PET-MRI) for staging of muscle-invasive bladder cancer.

e16002 Background: Standard of care imaging for staging MIBC is computed tomography (CT) abdomen and pelvis despite poor diagnostic accuracy. The addition of FDG-PET to evaluate biologic activity has been shown to improve detection of metastatic bladder cancer. Better soft tissue characterization with MRI may improve detection of local disease. We hypothesized that simultaneous acquisition of FDG-PET and MRI images (PET-MRI) would allow for more accurate preoperative staging in patients with MIBC. Methods: 21 patients with MIBC and planned radical cystectomy with lymph node dissection were enrolled. Four radiologists (2 senior, 2 junior) with expertise in MRI and PET independently reviewed MRI and FDG-PET scans, respectively, to determine: 1) extent of the primary bladder tumor; and 2) involvement of local lymph nodes and distant sites of disease. Combined radiologist reads were performed (senior MRI and junior PET and vice versa). Imaging results were compared to surgical pathology. Results: 18 patients were included in the final analysis (3 PET-MRI scans excluded due to technical pitfalls with image acquisition). Final pathology revealed 10 patients (56%) with muscle invasion and only 2 patients (11%) with lymph node involvement. Combined analyses of PET-MRI accurately detected the extent of the primary tumor (sensitivity 0.84, specificity 0.50, PPV 0.70, NPV 0.70), but was less accurate for the detection of lymph node involvement (sensitivity 0.00, specificity 1.00, no calculable PPV, NPV 0.91). Senior MRI radiologist had improved PPV and NPV for extent of primary tumor compared to junior MRI radiologist (PPV 0.71 vs 0.56, NPV 0.83 vs. 0.50), and senior PET radiologist had improved PPV with similar NPV for extent of primary tumor (PPV 1.00 vs 0.78, NPV 0.50 vs 0.55). No patient was determined to have distant metastatic disease. Conclusions: To our knowledge, this is the first study exploring the use of PET-MRI for staging MIBC. This novel imaging modality demonstrated promise in detecting the extent of the primary tumor. Further investigation of FDG-PET-MRI is needed to better determine its potential utility in staging MIBC.

Hepatectomy for rapidly growing solitary liver metastasis from non-small cell lung cancer: a case report

BackgroundPatients with liver metastasis from non-small lung cancer (NSCLC) usually have multiple metastases at other sites and thus rarely undergo liver surgery. We present a case involving successful resection of rapidly growing liver metastasis from squamous cell carcinoma of the lung.Case presentationA 74-year-old man had undergone left lower lobectomy for squamous cell carcinoma of the lung, which was diagnosed pathologically as stage IA. A computed tomography (CT) scan that was taken 12 months after lung resection showed an irregularly shaped mass lesion (size, 8.3 cm) in segment five of the liver. Retrospectively, the mass was identifiable on CT 6 months before this initial recognition. Although the lesion showed rapid growth, positron emission tomography and brain magnetic resonance imaging ruled out the possibility of other metastatic lesions. Therefore, we performed right hepatectomy 14 months after the initial lung surgery. The patient was pathologically diagnosed with liver metastasis from lung cancer and has remained free from recurrence 41 months after the liver surgery, without receiving any adjuvant chemotherapy.ConclusionsAlthough there is no reliable clinical indicator for selecting oligo-recurrence, hepatectomy could be an option for solitary liver metastasis from NSCLC for patients who are in good health.

Assessment of Myocardial Viability in Ischemic Heart Disease by PET/MRI: Comparison of Left Ventricular Perfusion, Hibernation, and Scar Burden

Hybrid positron emission tomography-magnetic resonance (PET-MR) is a novel imaging technology that enables a comprehensive assessment of myocardial viability. The aim of this study was to intra-individually compare simultaneously acquired viability parameters from MRI and PET to determine complementary and redundant information. Thirty-nine patients with ischemic heart disease (IHD) underwent cardiac PET-MR for myocardial viability assessment. Cardiac magnetic resonance (CMR), including late gadolinium enhancement (LGE), and PET, including a dynamic dual-tracer acquisition of [13N]ammonia ([13N]NH3)/[18F]fluorodeoxyglucose ([18F]FDG), were performed simultaneously. Allocation, extent, and transmural degree of left ventricular (LV) scars were measured from LGE. Perfusion, viability, and hibernation were assessed by PET. A comparison of scar location revealed six more areas of infarction on MR than on PET. Mean LV scarring by CMR was 14% (range, 2% to 42%) and 14% (range, 1% to 46%) by PET (CMR vs. PET: p = 0.9). An intra-individual comparison of scarring showed a good inter-method correlation (r = 0.7), which was also evident in the subgroup with low ejection fraction (EF) (r = 0.6). Hibernation and transmural degree of scars showed a moderate to weak correlation (r = 0.4), which was even worse in the low EF group (r = 0.1). In patients with IHD, there was a good correlation between PET and CMR for the LV scar extent using hybrid cardiac PET-MR. The degree of transmural scarring by CMR showed no correlation to PET hibernation. Therefore, cardiac PET-MR might be a suitable tool for a comprehensive assessment of myocardial viability if used to predict response to cardiac reperfusion strategies.

Exercise training alters lipoprotein particles independent of brown adipose tissue metabolic activity.

SummaryIntroductionNew strategies for weight loss and weight maintenance in humans are needed. Human brown adipose tissue (BAT) can stimulate energy expenditure and may be a potential therapeutic target for obesity and type 2 diabetes. However, whether exercise training is an efficient stimulus to activate and recruit BAT remains to be explored. This study aimed to evaluate whether regular exercise training affects cold‐stimulated BAT metabolism and, if so, whether this was associated with changes in plasma metabolites.MethodsHealthy sedentary men (n = 11; aged 31 [SD 7] years; body mass index 23 [0.9] kg m−2; VO2 max 39 [7.6] mL min−1 kg−1) participated in a 6‐week exercise training intervention. Fasting BAT and neck muscle glucose uptake (GU) were measured using quantitative [18F]fluorodeoxyglucose positron emission tomography–magnetic resonance imaging three times: (1) before training at room temperature and (2) before and (3) after the training period during cold stimulation. Cervico‐thoracic BAT mass was measured using MRI signal fat fraction maps. Plasma metabolites were analysed using nuclear magnetic resonance spectroscopy.ResultsCold exposure increased supraclavicular BAT GU by threefold (p < 0.001), energy expenditure by 59% (p < 0.001) and plasma fatty acids (p < 0.01). Exercise training had no effect on cold‐induced GU in BAT or neck muscles. Training increased aerobic capacity (p = 0.01) and decreased visceral fat (p = 0.02) and cervico‐thoracic BAT mass (p = 0.003). Additionally, training decreased very low‐density lipoprotein particle size (p = 0.04), triglycerides within chylomicrons (p = 0.04) and small high‐density lipoprotein (p = 0.04).ConclusionsAlthough exercise training plays an important role for metabolic health, its beneficial effects on whole body metabolism through physiological adaptations seem to be independent of BAT activation in young, sedentary men.

A whole-body FDG PET/MR atlas for multiparametric voxel-based analysis

Quantitative multiparametric imaging is a potential key application for Positron Emission Tomography/Magnetic Resonance (PET/MR) hybrid imaging. To enable objective and automatic voxel-based multiparametric analysis in whole-body applications, the purpose of this study was to develop a multimodality whole-body atlas of functional 18F-fluorodeoxyglucose (FDG) PET and anatomical fat-water MR data of adults. Image registration was used to transform PET/MR images of healthy control subjects into male and female reference spaces, producing a fat-water MR, local tissue volume and FDG PET whole-body normal atlas consisting of 12 male (66.6 ± 6.3 years) and 15 female (69.5 ± 3.6 years) subjects. Manual segmentations of tissues and organs in the male and female reference spaces confirmed that the atlas contained adequate physiological and anatomical values. The atlas was applied in two anomaly detection tasks as proof of concept. The first task automatically detected anomalies in two subjects with suspected malignant disease using FDG data. The second task successfully detected abnormal liver fat infiltration in one subject using fat fraction data.

Multimodal Medical Image Sensor Fusion Model Using Sparse K-SVD Dictionary Learning in Nonsubsampled Shearlet Domain

Multimodal medical image sensor fusion (MMISF) has a significant role for better visualization of the diagnostic statistics computed by integrating the vital information taken from input source images acquired using multimodal imaging sensors. The MMISF also helps the medical professionals in precise diagnosis of several critical diseases and its treatment. Often, images taken from different imaging sensors are degraded by noise interferences during acquisition or data transmission that leads to the false perception of noise as a useful feature of the image. This paper presents a novel fusion framework for multimodal neurological images, which is able to capture small-scale details of input images with original structural details. In its procedural steps, at first, source images get decomposed by the nonsubsampled shearlet transform (NSST) into a low-frequency (lf) and several high-frequency (hf) components to separate out the two basic characteristics of source image, i.e., principal information and edge details. The lf layers get fused with a sparse representation-based model, and the hf components are merged by the guided filtering-based approach. Finally, fused images are reconstructed by employing the inverse NSST. The superiority of the proposed MMISF approach is confirmed by a large extent of analytical experimentations on the different real magnetic resonance single-photon emission computed tomography, magnetic resonance-positron emission tomography and computed tomography magnetic resonance neurological image data sets. Based on all these experimental results, it is stated that the proposed MMISF approach is superior to several other approaches as it produces better visually fused images with improved computational measures.

Coronary microvascular dysfunction in hypertrophic cardiomyopathy detected by Rubidium-82 positron emission tomography and cardiac magnetic resonance imaging

Coronary microvascular dysfunction in hypertrophic cardiomyopathy detected by Rubidium-82 positron emission tomography and cardiac magnetic resonance imaging

Very Early Response Evaluation by PET/MR in Patients with Lung Cancer-Timing and Feasibility.

Purpose: With the increasing number of therapy options available for patients with lung cancer, early response evaluation is needed. We performed this pilot study to assess the feasibility of early, repeated Positron emission tomography-magnetic resonance (PET/MR), the impact of timing and the capability for response prediction in lung tumors during chemotherapy. Methods: Patients with stage IV non-small cell lung cancer referred for chemotherapy were prospectively recruited. Fluorine-18-Fluorodeoxyglucose(18F-FDG)-PET/MR scans were performed prior to, during and after the first or second cycle of chemotherapy. Primary tumors were defined on all scans and size, FDG-uptake and apparent diffusion coefficient (ADC) were measured. Early response was described over time and a Standard Linear Mixed Model was applied to analyze changes over time. Results: 45 FDG-PET/MR scans were performed in 11 patients. Whereas the overall changes measured by ADC did not change significantly, there was an overall significant decrease in FDG-uptake from pre to post treatment scans. There was no difference in the FDG-uptake measured 1 or 3 weeks after therapy, but uptake measured 2 weeks after therapy differed from measurements at week 3. Changes measured in patients scanned during the first treatment cycle appeared more pronounced than during the second cycle. Conclusions: This pilot study indicates that response evaluation shortly after initiation of chemotherapy appears concordant with later evaluation and probably more reliable than evaluation midway between cycles. Responses during or after the first cycle of chemotherapy rather than during subsequent cycles are likely to be more readily measured.

Hybrid positron emission tomography-magnetic resonance imaging for assessing different stages of cardiac impairment in patients with Anderson-Fabry disease: AFFINITY study group.

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with multi-organ dysfunction. While native myocardial T1 mapping by magnetic resonance (MR) allow non-invasive measurement of myocyte sphingolipid accumulation, 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and MR are able to identify different pathological patterns of disease progression. We investigated the relationship between T1 mapping and 18F-FDG uptake by hybrid PET-MR cardiac imaging in AFD female patients. Twenty AFD females without cardiac symptoms underwent cardiac PET-MR using 18F-FDG for glucose uptake. In all patients and in seven age- and sex-matched control subjects, T1 mapping was performed using native T1 Modified Look-Locker Inversion-recovery prototype sequences. 18F-FDG myocardial uptake was quantified by measuring the coefficient of variation (COV) of the standardized uptake value using a 17-segment model. T1 values of AFD patients were lower compared with control subjects (1236 ± 49 ms vs. 1334 ± 27 ms, P < 0.0001). Focal 18F-FDG uptake with COV >0.17 was detected in seven patients. COV was 0.32 ± 0.1 in patients with focal 18F-FDG uptake and 0.12 ± 0.04 in those without (P < 0.001). Patients with COV >0.17 had higher T1 values of lateral segments of the mid ventricular wall, compared with those with COV ≤0.17 (1216 ± 22 ms vs. 1160 ± 59 ms, P < 0.05). In females with AFD, focal 18F-FDG uptake with a trend towards a pseudo-normalization of abnormal T1 mapping values, may represent an intermediate stage before the development of myocardial fibrosis. These findings suggest a potential relationship between progressive myocyte sphingolipid accumulation and inflammation.