Use of iodine-123 metaiodobenzylguanidine myocardial imaging to predict the effectiveness of β-blocker therapy in patients with dilated cardiomyopathy

It is crucial to predict drug effectiveness in chronic disease, such as dilated cardiomyopathy (DCM), in which the left ventricular (LV) function might be improved by -blocker therapy. As the functional improvement effected by -blocker therapy takes more than 2 months, we investigated whether iodine-123 metaiodobenzylguanidine (¹²³I-MIBG) imaging could be used to predict drug effectiveness. We studied 13 patients (11 men and two women; mean age, 43±13 years) with DCM and seven normal subjects (six men and one woman; mean age, 48±16 years). We obtained myocardial single-photon emission tomography (SPET) images 15 min and 4 h after administration of¹²³I-MIBG (111 MBq). Studies were performed in the patients with DCM before and 1 and 3 months after the administration of metoprolol and in the normal subjects. We calculated the regional¹²³I-MIBG washout rate (r-WR) in the SPET image, and the global¹²³I-MIBG washout rate (g-WR) and heart-mediastinum activity ratio (H/M) using the anterior planar image. We classified patients into those showing a 5% increase in LV ejection fraction (LVEF) at 3 months compared with LVEF values before the treatment (group 1,n=7) and those showing a <5% increase in LVEF (group 11,n=6). In group I, the r-WR values at pretreatment and at 1 month and 3 months of treatment, respectively, were 36%±19%, 29%±14%* and 25%±13%* in the anterior segment, 39%±17%, 33%±17%** and 28%±17%* in the lateral segment, 36%±16%, 31%±14%* and 22%±12%** in the septal segment and 40%±11%, 37%±19% and 31%±18%* in the inferior segment; the g-WR was 45%±11%, 43%±10% and 34%±9%^*, respectively (*P<0.05, **P<0.01 vs pretreatment). In group II, there were no significant changes in regional or global parameters during the 3-month period. In normal subjects, the r-WR values in each of the anterior, lateral, septal and inferior segments were significantly lower than those in groups I and II. These values were 18%±9%, 18%±15%, 20%±12% and 21%±15%, respectively. This study demonstrated that with regional assessment¹²³I-MIBG SPET imaging can be used to predict the functional improvement of LVEF at 1 month of -blocker therapy in patients with DCM.     

Cardiac magnetic resonance: is phonocardiogram gating reliable in velocity-encoded phase contrast imaging?

Objectives

To assess the diagnostic accuracy of phonocardiogram (PCG) gated velocity-encoded phase contrast magnetic resonance imaging (MRI).

Methods

Flow quantification above the aortic valve was performed in 68 patients by acquiring a retrospectively PCG- and a retrospectively ECG-gated velocity-encoded GE-sequence at 1.5?T. Peak velocity (PV), average velocity (AV), forward volume (FV), reverse volume (RV), net forward volume (NFV), as well as the regurgitant fraction (RF) were assessed for both datasets, as well as for the PCG-gated datasets after compensation for the PCG trigger delay.

Results

PCG-gated image acquisition was feasible in 64 patients, ECG-gated in all patients. PCG-gated flow quantification overestimated PV (Δ 3.8?±?14.1?cm/s; P?=?0.037) and underestimated FV (Δ -4.9?±?15.7?ml; P?=?0.015) and NFV (Δ -4.5?±?16.5?ml; P?=?0.033) compared with ECG-gated imaging. After compensation for the PCG trigger delay, differences were only observed for PV (Δ 3.8?±?14.1?cm/s; P?=?0.037). Wide limits of agreement between PCG- and ECG-gated flow quantification were observed for all variables (PV: -23.9 to 31.4?cm/s; AV: -4.5 to 3.9?cm/s; FV: -35.6 to 25.9?ml; RV: -8.0 to 7.2?ml; NFV: -36.8 to 27.8?ml; RF: -10.4 to 10.2?%).

Conclusions

The present study demonstrates that PCG gating in its current form is not reliable enough for flow quantification based on velocity-encoded phase contrast gradient echo (GE) sequences.

Key Points

? Phonocardiogram gating is an alternative to ECG-gating in cardiac MRI. ? Phonocardiogram gating shows only limited reliability for velocity-encoded cardiac MRI. ? Further refinements of the post-processing algorithm are necessary.     

Late gadolinium enhancement on cardiac magnetic resonance imaging: is it associated with a higher incidence of nonsustained ventricular tachycardia in patients with idiopathic dilated cardiomyopathy?

Purpose  

Late gadolinium enhancement (LGE) during cardiac magnetic resonance imaging (MRI) can be seen in patients with myocardial fibrosis accompanied by myocardial infarction and cardiomyopathy. Some idiopathic dilated cardiomyopathy (DCM) patients have fibrosis in the myocardium and show LGE during cardiac MRI. The purpose of this study was to investigate the clinical significance of LGE in patients with DCM.     

Does myocardial fibrosis hinder contractile function and perfusion in idiopathic dilated cardiomyopathy? PET and MR imaging study

PURPOSE: To prospectively evaluate, by using positron emission tomography (PET) and magnetic resonance (MR) imaging, the interrelationships between regional myocardial fibrosis, perfusion, and contractile function in patients with idiopathic dilated cardiomyopathy (DCM). MATERIALS AND METHODS: The study protocol was approved by the hospital ethics committee, and all subjects gave written informed consent. Sixteen patients with idiopathic DCM (mean age, 54 years +/- 11 [standard deviation]; nine men) and six healthy control subjects (mean age, 28 years +/- 2; five men) were examined with PET and MR tissue tagging. Oxygen 15-labeled water and carbon monoxide were used as tracers at PET to assess myocardial blood flow (MBF) and the perfusable tissue index (PTI), which is inversely related to fibrosis. MBF was determined at rest and during pharmacologically induced hyperemia. Maximum circumferential shortening (E(cc)) was determined with MR tissue tagging. Student t tests were performed for comparison of data sets, and linear regression was used to investigate the association between parameters. RESULTS: Mean global hyperemic MBF (2.23 mL/min/mL +/- 0.73), E(cc) (-10.5% +/- 2.9), and PTI (0.95 +/- 0.10) were lower in the patients with DCM than in the control subjects (4.33 mL/min/mL +/- 0.85, -17.4% +/- 0.6, and 1.09 +/- 0.12, respectively; P < .05 for all). In the patients with DCM, regional PTI was related to E(cc) (r = -0.21, P = .009) but not to resting or hyperemic MBF. Furthermore, regional E(cc) was correlated to both resting (r = -0.28, P = .004) and hyperemic MBF (r = -0.29, P < .001). In addition, the ratio of left ventricular end-diastolic volume to mass, as a reflection of wall stress, was related to global hyperemic MBF (r = -0.52, P = .047) and to global E(cc) (r = 0.69, P = .003). CONCLUSION: In idiopathic DCM, the extent of myocardial fibrosis is related to the impairment in contractile function, whereas fibrosis and perfusion do not seem to be interrelated. The degree of impairment of hyperemic myocardial perfusion is related to contractility and end-diastolic wall stress.     

Three-dimensional magnetic resonance spectroscopic imaging in the substantia nigra of healthy controls and patients with Parkinson��s disease

Objectives  

To investigate the substantia nigra in patients with Parkinson’s disease three-dimensional magnetic resonance spectroscopic imaging with high spatial resolution at 3 Tesla was performed. Regional variations of spectroscopic data between the rostral and caudal regions of the substantia nigra as well as the midbrain tegmentum areas were evaluated in healthy controls and patients with Parkinson’s disease.     

Cardiac chamber quantification using magnetic resonance imaging at 7 Tesla—a pilot study

Objectives  

Interest in cardiovascular magnetic resonance (CMR) at 7 T is motivated by the expected increase in spatial and temporal resolution, but the method is technically challenging. We examined the feasibility of cardiac chamber quantification at 7 T.     

Can magnetic resonance imaging predict the success of parturition in oxytocin-induced pregnant women?

The aim of this study was to assess whether magnetic resonance imaging could predict the outcome of attempted vaginal delivery in a group of pregnant women whose parturition had to be induced by oxytocin. The signal intensity and morphology alterations in the cervix of 21 full-term pregnant women were analyzed before the induction of parturition. T2-weighted gradient echo sequences were utilized and signal intensity in the cervix was measured from the anterior and posterior lips of the cervix. An index indicating the brightness range of the cervix was formulated to overcome the effects of the individual intensity changes. Imaging features including the signal intensity and the evidence of effacement were correlated with the actual type of delivery performed. Images were also assessed visually by two independent radiologists. Statistical analysis of brightness indexes that were considered to have a predictive value as an indicator for possible delivery was not significant. However, visually assessed signal intensity of the cervix correlated strongly with the type of delivery. Effacement itself was the most reliable parameter in predicting the progress of the delivery. In conclusion, MR imaging seems to be useful for predicting normal parturition in full-term pregnant women who need oxytocin induction. However, the presence of effacement seems to be a more reliable and practical parameter that will be preferred in that prediction. Received: 21 October 1998; Revised: 19 April 1999; Accepted: 21 October 1999     

Clinical safety of cardiac magnetic resonance imaging at 3 T early after stent placement for acute myocardial infarction

The purpose of this study was to prospectively evaluate the safety of cardiac magnetic resonance (CMR) imaging at 3 T performed early (less than 14 days) after bare metal or drug-eluting coronary stent implantation in patients with acute myocardial infarction (AMI). Seventy-two consecutive patients with AMI treated by percutaneous revascularisation with a stent underwent CMR examination with a median delay of 6 days. Patients were followed-up for major adverse cardiac events, during hospitalisation and at 6 months. After CMR imaging, no acute stent thrombosis, death or repeated AMI were recorded at 6-month follow-up. Two symptomatic in-stent restenoses and two silent in-stent restenoses were recorded, at a mean delay of 106 days. In our population, we found a target revascularisation rate of 5.6%. This is consistent with the 6-month event rates after coronary artery stent (CAS) placement for AMI, evaluated by several studies. This preliminary clinical study supports the safety of 3-T CMR imaging performed early after coronary stent placement.     

Is magnetic resonance cholangiopancreatography the new gold standard in biliary imaging?

The timing and technique of perioperative biliary imaging in relation to laparoscopic surgery remains controversial. This study assessed the predictive value of magnetic resonance cholangiopancreatography (MRCP) in the diagnosis of biliary pathology. Clinical, laboratory and investigational data were evaluated from 374 patients undergoing MRCP at two hospital sites over a 5-year period. MRCP findings were compared with endoscopic retrograde cholangiopancreatography (ERCP) or operative findings and appropriate clinical endpoints. Complete data were available for 351 of the 374 patients (94%), of whom 232 (66%) were female. Median age was 64 years. The predominant presentation was abdominal pain (n = 190). Features of pancreatitis were present in 59, cholangitis in 26 and jaundice in 109 patients. Ultrasound was the initial investigation in 312 (89%) (176-gallstone positive). Common duct dilatation was evident in 114 patients and ductal calculi in 31. ERCP was successful in 212/283 (75%) patients. Significant ERCP induced pancreatitis occurred in 12 (5.6%). Comparison between MRCP and ERCP was not possible in 85 due to failure of either technique. Nine patients underwent other investigations including intraoperative cholangiogram (IOC), percutaneous transhepatic cholangiogram (PTC) and were included. Of the 221 patients with full comparative data available the MRCP showed a sensitivity of 97.98% and specificity of 84.4%. MRCP is highly sensitive and specific for choledocholithiasis and avoids the need for invasive imaging in most patients with suspected choledocholithiasis.     

Diffusion-weighted magnetic resonance imaging in Marchiafava–Bignami disease: follow-up studies

Marchiafava–Bignami disease (MBD), an acute toxic demyelination of the corpus callosum in alcoholics, is associated with poor evolution in the majority of patients. We report here the early and late diffusion magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) studies of two patients suffering from MBD with favourable outcome. Diffusion and anatomical MRI changes were parallel to the clinical evolution, suggesting that MRI studies can be helpful for diagnosis and follow-up. Unlike in stroke, restricted diffusion on ADC maps does not seem to be a sign of irreversibility.     

Positron emission tomography/magnetic resonance imaging: the next generation of multimodality imaging?

Multimodal imaging is now well-established in routine clinical practice. Especially in the field of nuclear medicine, new positron emission tomography (PET) installations comprise almost exclusively combined PET/computed tomography (CT) scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT. Magnetic resonance imaging (MRI) offers, compared with CT, better contrast among soft tissues as well as functional-imaging capabilities. Therefore, the combination of PET with MRI provides many advantages that go far beyond simply combining functional PET information with structural MRI information. Many technical challenges, including possible interference between these modalities, have to be solved when combining PET and MRI, and various approaches have been adapted to resolving these issues. Here, we present an overview of current working prototypes of combined PET/MRI scanners from different groups. In addition, besides PET/MRI images of mice, the first such images of a rat acquired with the first commercial clinical PET/MRI scanner, are presented. The combination of PET and MRI is a promising tool in preclinical research and will certainly progress to clinical application.     

Imaging in multiple myeloma: Computed tomography or magnetic resonance imaging?

Multiple myeloma (MM) is the second most common type of hematological disease with its incidence rising in the elderly. In MM, the extent of the bone disease increases both morbidity and mortality. The detection of lytic bone lesions on imaging, especially computerized tomography (CT) and magnetic resonance imaging (MRI) is crucial to separate asymptomatic from symptomatic MM patients even when no clinical symptoms are present. Although radiology is essential in the staging and management of patients with MM there is still high variability in the choice between MRI and CT. In addition, there is still suboptimal agreement among readers. The potential of medical imaging in MM is largely under-evaluated: artificial intelligence, radiomics and new quantitative methods to report CT and MRI will improve imaging usage.     

Remote scanning support in magnetic resonance imaging: Friend or foe?

IntroductionRecent advances in technology have seen the introduction of remote scanning capabilities become a reality for departments, allowing staff to remotely access, observe and even scan without being by the scanner side. The COVID-19 pandemic has accelerated use of remote working which also aligns with the direction of travel for healthcare more widely. However for technology to succeed it needs to be acceptable for use by radiographers in clinical practice.MethodsFollowing trial of a remote scanning technology, a group of radiographers were surveyed for their views on its use in practice. The survey was based on the Technology Acceptance Model as well as providing opportunity for open feedback on views regarding the technology.ResultsPerceived ease of use was high but appears to have little influence over overall intention to use. Perceived usefulness was lower and demonstrated correlations with attitude towards and intended use of the remote technology, suggesting that this is a key area to address which would positively impact on acceptance. Other considerations that would help support effective implementation were highlighted with the majority stating the technology as friend rather than foe.ConclusionAs an early evaluation of practitioner views on remote scanning within MRI, the results highlight the areas that would benefit from further development before further roll out in practice. A clear vision of its use and robust governance is needed to effectively support its implementation and acceptance by radiographers.Implications for practiceIntroducing remote scanning technology has potential to support training and share skills of experienced radiographers across multiple locations. It has the potential to transform the way MRI departments work and increase safer supervision to enable wider utilization of the support workforce.     

Simultaneous in vivo magnetic resonance imaging and radioactive measurements with the β-MicroProbe

Purpose Multimodal instrumentation is a new technical approach allowing simultaneous and complementary in vivo recordings of complementary biological parameters. To elucidate further the physiopathological mechanisms in intact small animal models, especially for brain studies, a challenging issue is the actual coupling of magnetic resonance imaging (MRI) techniques with positron emission tomography (PET): it has been shown that running the technology for radioactive imaging in a magnet alters the spatiotemporal performance of both modalities. Thus, we propose an alternative coupling of techniques that uses the β-MicroProbe instead of PET for local measurements of radioactivity coupled with MRI. Methods We simultaneously recorded local radioactivity due to [¹⁸F]MPPF (a 5-HT_1A receptor PET radiotracer) binding in the hippocampus with the β-MicroProbe and carried out anatomical MRI in the same anaesthetised rat. Results The comparison of [¹⁸F]MPPF kinetics obtained from animals in a magnet with kinetics from a control group outside the magnet allowed us to determine the stability of tracer biokinetic measurements over time in the magnet. We were thus able to show that the β-MicroProbe reliably measures radioactivity in rat brains under an intense magnetic field of 7 Tesla. Conclusion The biological validation of a β-MicroProbe/MRI dual system reported here opens up a wide range of future multimodal approaches for functional and pharmacological measurements by the probe combined with various magnetic resonance technologies, including anatomical MRI, functional MRI and MR spectroscopy.     

Signal changes in cortical laminar necrosis—evidence from susceptibility-weighted magnetic resonance imaging

Introduction  Two types of infarcts can be identified depending on the circumstances leading to its generation-infarcts with pannecrosis and infarcts with selective neuronal loss. Cortical laminar necrosis (CLN) can occur due to various etiologies of which infarctions and hypoxia are the commonest. Infarction results in pannecrosis whereas hypoxia and incomplete infarction result in selective neuronal loss with the presence of viable cells, glial proliferations, and deposition of paramagnetic substances. We investigated patients with CLN with susceptibility-weighted imaging (SWI), a technique highly sensitive to even traces of paramagnetic agents or hemorrhagic components. Methods  We retrospectively reviewed medical records of patients diagnosed with CLN as per standard criterion. Demographic characteristics and etiologies were recorded. Findings in magnetic resonance images including SWI were analyzed. Results  We identified 11 patients with CLN, six males and five females with age range of 4–64 years. Etiologies included hypoxia in two patients and infarction in the nine patients. SWI detected diffuse linear hypointensities along the gyral margins in CLN due to hypoxic ischemic encephalopathy. Linear dot like hypointensities were identified in one patient with infarction. Conclusion  CLN due to hypoxic ischemic encephalopathy display linear gyral hypointensities and basal ganglia hypointensities that are identifiable in SWI and may represent mineralization. This might be related to iron transport across the surviving neurons from basal ganglia to the cortex, which is not possible in complete infarction. SWI may be helpful in understanding the pathophysiological aspects of CLN due to complete infarction and hypoxia.     

Measurement of femoral anteversion by magnetic resonance imaging — evaluation of a new technique in children and adolescents

Anteversion of the femoral neck was measured by magnetic resonance imaging (MRI) in 19 children (37 hips) preoperatively before femoral rotation osteotomies. The results of this new technique were compared with values for anteversion obtained by computed-tomographic (CT) scanning and ultrasound. In order to determine the correlation between the three different methods and to assess their reliability, the measurements were performed independently by two observers at different times. There was a high correlation (Pearson's correlation coefficient) between MRI results and CT scan (r = 0.77) as well as MRI and sonography (r = 0.81), although the mean anteversion angles obtained by computerized tomography (34.0°, range 5–82°) and ultrasound (25.6°, 10–40°) were larger than the MRI values (23.2°, 0–65°), which can be explained by the different measurement techniques. Mean inter-rater as well as intra-rater reliability was high for MRI (r = 0.97andr = 0.97) and CT (r = 0.99andr = 0.96) but slightly less for sonography (r = 0.88andr = 0.88). MRI is a novel method for evaluating femoral anteversion that does not require ionizing raiation, allows a precise anatomical measurement and reliable results. MRI is recommended for preoperative planning of pediatric femoral rotation osteotomy cases.