Cardiac radionuclide imaging in clinical decision making

A substantial body of evidence documents the high diagnostic accuracy and prognostic power of cardiac nuclear imaging in the assessment of patients with suspected or known coronary artery disease (CAD). Myocardial perfusion scintigraphy (MPS) provides significant incremental information over and above that obtained by clinical and exercise electrocardiography variables. In patients with chronic CAD nuclear imaging has the ability to identify patients likely to benefit from revascularization from others in whom invasive treatment does not improve their prognosis. In patients presenting with chest pain in the emergency department, MPS can contribute substantially in the implementation of rapid-investigation protocols, allowing for timely management decisions and early discharge of low-risk individuals. In stabilized patients after an acute coronary event, MPS performed within a few days following the insult improves significantly risk stratification and facilitates the selection of the appropriate therapeutic strategy. In the setting of ischaemic left ventricular dysfunction, the presence of considerable amount of viable myocardium, as assessed by radionuclide imaging, is associated with improved survival, provided that these patients are submitted to revascularization. Beyond its clinical efficacy, MPS has also found to be very cost effective and has become integral part of numerous European and American guidelines.     

Whole-body MR imaging in psoriatic arthritis: Additional value for therapeutic decision making

Purpose

In psoriatic arthritis (PsA) multiple locations may show inflammatory changes not always readily accessible to clinical exam. Often, clinical exam is inconclusive and the decision to initiate or adapt therapy is difficult. Whole body (WB)-MRI may help in this situation by providing a comprehensive overview of affected areas/joints. The purpose of this study was to make a proof of concept whether WB-MRI in psoriatic arthritis is feasible and can provide additional information compared to clinical examination alone with regard to therapeutic decision making in patients with PsA and inconclusive clinical situation.

Materials and Methods

30 patients with PsA and diffuse musculoskeletal pain were examined. A WB-MRI protocol was implemented on a 1.5 Tesla scanner using coronal and sagittal STIR- (TR: 5800, TE: 54, matrix 384² pixels, FOV 400 mm) and pre- and steady-state-post-Gadolinium-VIBE sequences (TR: 9.82, TE: 4.53, matrix 384 × 307 pixels, FOV: 400 mm). MRI was evaluated for image quality and inflammatory findings by two readers in consensus and compared to clinical exam.

Results

The WB-MR-exam was well tolerated by all patients. Image quality was rated good to excellent in 26 of 30 patients (86.6%). WB-MRI detected significantly (p < 0.001) more areas of synovitis/enthesitis than clinical exam except for the hands and feet. MRI was able to detect unknown destructive bony changes in 10 patients (53%). In 22 patients (73.3%) the therapy regimen was modified, in 18 patients (62%) TNF-alpha-inhibitors were started.

Conclusion

Whole-body MRI (WB-MRI) may be integrated in the diagnostic work-up of patients with psoriatic arthropathy facilitating individual adaptation of therapeutic strategy.     

Osteosarcoma: MR imaging after preoperative chemotherapy

The authors reviewed 76 magnetic resonance (MR) images of 38 patients with osteosarcoma treated with preoperative chemotherapy (intraarterial cisplatin with or without systemic chemotherapy). Histologic maps of the surgical tumor specimens in 33 cases were correlated with either late-chemotherapy or postchemotherapy MR images. There were four MR patterns--dark, mottled or speckled, homogeneous, and cystic--that corresponded to different amounts of tumor matrix, granulation tissue, hemosiderin deposits, fluid-filled cysts, and residual viable tumor. Nested foci of residual viable tumor could not be specifically identified, although tumor progression or skip metastases were accurately depicted in four patients. Other findings included (a) peritumoral edema in the soft tissues and intramedullary space that shrank with chemotherapy, (b) chemotherapy effect in the surrounding soft tissues, (c) a dark rim around the extramedullary component of the tumors corresponding to a collagenous capsule continuous with the periosteum, (d) development of metaphyseal hemorrhages and bone marrow infarcts, and (e) intramedullary vascular channels.     

The use of nuclear cardiology in clinical decision making

Extensive data exist to support the role of myocardial perfusion single-photon emission computed tomography (MPS) in risk stratification. Normal MPS studies usually are associated with very low risk, and patient risk increase significantly as a function of MPS results. Ventricular function measurements from gated single-photon emission computed tomography further augment risk stratification, particularly with respect to identifying patients at risk of cardiac death. Ancillary findings are prognostically important, particularly in the setting of normal or near-normal MPS results. Recent data suggest that MPS results can identify which patients will benefit from revascularization versus medical therapy and have expanded the understanding of how stress MPS is helpful in the identification of risk, enhanced the means of identifying risk, and improved its use as a means to identify optimal posttest treatment.     

Osteosarcoma: chemotherapy-induced changes at MR imaging.

Fifty-seven patients undergoing chemotherapy for osteosarcoma underwent evaluation with magnetic resonance (MR) imaging to identify changes related to a good or poor response. Spin-echo MR images obtained after preoperative chemotherapy were compared with images obtained before treatment. Histopathologic examination of each resected specimen was used to quantify the response. An increase in tumor volume and increased or unchanged edema were predictive of a poor histopathologic response (predictive values, 85%-92%). Decreased or unchanged tumor volume and a decrease in edema were poor predictors of a good response (predictive values, 56%-62%). Improved tumor demarcation, an increase in the size of areas of low signal intensity, and a decrease in joint effusion occurred independently of histopathologic response in almost half of the patients. With a subjective interpretation of MR images, poor respondents can be identified if an increase in tumor volume or no decrease in the amount of edema is seen. Subjective criteria do not contribute to the identification of good respondents.     

MEL AS综合征的MRI和MRS表现及临床意义

目的：分析线粒体脑肌病并高乳酸血症与卒中样发作（MELAs）综合征的MRI和MRS表现,探讨MRI对该病早期诊断与鉴别诊断的临床价值。方法：回顾性分析24例经临床表现及肌肉病理活检确诊的MELAS综合征患者,24例均行常规MRI（包括T1WI平扫与增强扫描,T2WI,T2FLAIR）,14例行MRA,3例行DwI,3例行MRS。综合分析所有病例的多模态MRI特征。结果：24例（79个病灶）均出现大脑皮质或皮质下片状长T1长T2信号,以枕叶（29个）、颞叶（25个）和项叶（16个）受累为主,可双侧出现;14例MRA示病变区与动脉供血区域不吻合,4例可见血管增生;10例随访患者中7例发现病灶具有游走性;3例行DWI患者均可见扩散受限所致异常信号;TzFLAIR可同时显示新、旧病灶（呈不同程度高信号）,且所显示慢性期病灶的数目与DwI相同（2例）或更多（1例）。3例MRs均可见乳酸（Lac）峰增高,且不局限于MRI所显示的病灶内,1例较陈旧病灶可见氮一乙酰天门冬氨酸（NAA）峰降低。结论：MELAS综合征具有较特异的MRI表现;MRS提示病灶内和病灶外Lac峰增高,结合高乳酸血症,对该病早期确诊有重要价值。     

MR imaging: clinical use of the inversion recovery sequence

The properties of the inversion recovery (IR) sequence are considered and its use in clinical practice is illustrated. The effect of changing repetition time, inversion time (TI), and echo time; the method of data encoding; the type of data collection; and the method of image processing are analysed. Normal appearances and clinical examples in the central nervous system and the remainder of the body are used to illustrate the many options available with this sequence. The short TI IR sequence has advantages in magnetic resonance imaging of the body, and medium TI sequences are of value in localisation in the brain and in demonstrating contrast enhancement. Long TI sequences can be used in pediatrics and for separating tumour and oedema. Suppression or partial suppression of fat and fluid signals are two useful options with IR sequences.     

Neuro-Behcet''s disease: diffusion MR imaging and proton MR spectroscopy

We herein report the case of a 53-year-old woman with Behcet's disease and an acute T2-hyperintense lesion in left side of the pons. Echo-planar "trace" diffusion MR imaging revealed high signal intensity changes at the lesion site on b = 1000 s/mm(2) images, initially suggesting restricted diffusion. On corresponding apparent diffusion coefficient maps, however, the lesion had high signal intensity and high apparent diffusion coefficient values (1.22 x 10(-3) mm(2)/s), compared with the contralateral normal side of the pons (0.86 x 10(-3) mm(2)/s) and compared with the normal temporal white matter (0.80 x 10(-3) mm(2)/s). This was consistent with the presence of increased diffusion, hence vasogenic edema. Proton MR spectroscopy excluded acute infarction. This particular pattern (high signal intensity on b = 1000 s/mm(2) images in association with high apparent diffusion coefficient values) likely represented the acute inflammatory process associated with disrupted brain-blood barrier in the fulminant form of neuro-Behcet's disease. Follow-up examinations 相似文献   

Marchiafava-Bignami disease: longitudinal MR imaging and MR spectroscopy study

A case of Marchiafava-Bignami disease was serially evaluated with MR imaging and MR spectroscopy at 1, 2, 4, and 11 months after the onset of symptoms. The first MR imaging study showed extensive abnormal signal intensity of the corpus callosum without macroscopic changes; a diagnosis of Marchiafava-Bignami disease was made, and vitamin therapy was initiated. Follow-up studies showed progressive reduction of signal intensity abnormalities and residual callosal atrophy. MR spectroscopy revealed progressive reduction of the N-acetylaspartate:creatine ratio, with partial recovery in the last study, and a normalization of the choline:creatine ratio, which was initially slightly increased. Lactate was detectable during the subacute phase and was replaced by lipids after 4 months. This study confirmed the role of MR imaging in diagnosing Marchiafava-Bignami disease and particularly the value of MR spectroscopy in focusing the pathogenesis of the disease, monitoring its evolution and changes related to therapy.     

MR imaging and MR spectroscopy in prostate cancer management

Currently, endorectal coil MR imaging has the ability to improve accuracy in staging of localized prostate cancer. The addition of MR spectroscopic imaging has further improved the sensitivity of MR imaging for intraprostatic tumor localization. Additional refinements and techniques are expected to further improve the performance of MR imaging for prostate cancer imaging and to aid in patient management. Further studies are required to identify the ideal role for MR imaging in the diagnosis and management of prostate cancer.     

MR imaging and MR spectroscopy in rhizomelic chondrodysplasia punctata

A case of rhizomelic chondrodysplasia punctata was investigated with MR imaging of the brain and hydrogen-1 MR spectroscopy of the brain and blood. Areas with abnormal signal hyperintensity on T2-weighted images or hypointensity on T1-weighted images were detected in the subcortical white matter. MR spectroscopy of the brain showed that normal-appearing white matter was characterized by increased levels of mobile lipids and myo-inositol, reduced levels of choline, and the presence of acetate. The importance of these metabolic anomalies is correlated to the deficiency in plasmalogen biosynthesis.     

Stable xenon CT cerebral blood flow imaging: rationale for and role in clinical decision making

The stable xenon CT method of measuring cerebral blood flow has been investigated in research studies for over 10 years. Recently, it has been gaining clinical acceptance, primarily owing to a combination of several unique advantages it holds over other cerebral blood flow measurement techniques. The accuracy of this technique in quantifying low cerebral blood flow gives it a unique application in cases of brain death and acute stroke and it can be repeated after an interval of 20 min. making it possible to evaluate autoregulation and cerebrovascular reserve. Furthermore, cerebral blood flow information is directly coupled to CT anatomy. Although it is more difficult to administer than a standard CT scan, careful monitoring can ensure patient safety during the examination. In this article we review the physiologic and technical bases for the clinical application of xenon CT-derived quantitative cerebral blood flow information and discuss the advantages and disadvantages of the technique. We also describe its current clinical applications, including its usefulness in the evaluation of acute stroke, occlusive vascular disease, carotid occlusion testing, vasospasm, arteriovenous malformations, and head trauma management.     

Pantothenate kinase-associated neurodegeneration: MR imaging,proton MR spectroscopy,and diffusion MR imaging findings

We herein report the case of a 15-year-old male patient with pantothenate kinase-associated neurodegeneration. The classic "eye-of-the-tiger" appearance was initially present on the globus pallidi on T2-weighted MR images and had disappeared by the time of the 10-month follow-up examination. Fluid-attenuated inversion recovery images revealed marked hypointensity in the globus pallidi and dentate nuclei and high signal intensity changes in the deep cerebral white matter. Proton MR spectroscopy revealed markedly decreased N-acetylaspartate in the globus pallidi, associated with decreased N-acetylaspartate and increased myoinositol in the deep cerebral white matter. Diffusion MR images (b=1000 s/mm(2)) were negative (normal appearing) for deep cerebral white matter lesions, whereas apparent diffusion coefficient values were slightly increased (1.08-1.12 x 10(-3) mm(2)/s), compared with the apparent diffusion coefficient values from the normal white matter regions. Apparent diffusion coefficient values in the globus pallidi were lower than those in the unaffected thalamus.