Clinical applications of radionuclide imaging in the evaluation and management of patients with congenital heart disease

Non-invasive testing of children with congenital heart disease (CHD) began in the 1950s with the introduction of radionuclide studies to assess shunt fractions, pulmonary blood flow, and ventricular contractile function. Echocardiography and cardiac magnetic resonance imaging have since replaced radionuclide imaging in many of these roles. Concurrently, percutaneous and surgical repairs of complex CHD evolved, creating new roles for radionuclide imaging. In this paper on applications of radionuclide imaging in CHD, we review the multiple mechanisms for myocardial ischemia in CHD. We critically compare optimal radionuclide imaging techniques to other imaging modalities for assessing ischemia in CHD. We present the current role of nuclear imaging for assessing viability and pulmonary blood flow. We highlight the value added by advances in dedicated cardiac SPECT scanners, novel reconstruction software, and cardiac PET in performing low-dose radionuclide imaging in CHD. Finally, we discuss the emerging clinical indications for radionuclide imaging in CHD including coronary flow reserve assessment and evaluation of cardiovascular prosthesis and device infections.     

Diffusion-weighted MR imaging of the spinal cord

Diffusion-weighted MR imaging may increase the sensitivity and specificity of MR imaging for certain pathologic conditions of the spinal cord but is rarely performed because of several technical issues. We therefore tested a novel phase-navigated spin-echo diffusion-weighted interleaved echo-planar imaging sequence in seven healthy volunteers and six patients with intramedullary lesions. We performed diffusion-weighted MR imaging of the spinal cord with high spatial resolution. Different patterns of diffusion abnormalities observed in patient studies support the possible diagnostic impact of diffusion-weighted MR imaging for diseases of the spinal cord.     

MRI features of ovarian cystic lesions

The purpose of this article is to present the clinical and imaging features for the spectrum of ovarian cystic lesions, from benign to malignant and from tumorous to nontumorous. We review the imaging modalities for evaluating ovarian cystic lesions, especially magnetic resonance imaging (MRI) techniques. We present clinical and imaging features that can be used to help with the differential diagnosis of the spectrum of ovarian cystic lesions. We discuss the relevance of imaging features for distinguishing between benign and malignant ovarian cystic lesions. The characteristic clinical and imaging features of ovarian cystic lesions can provide criteria for making a diagnosis or substantially narrowing the differential diagnosis. Therefore, a careful assessment of ovarian cystic lesions is warranted. J. Magn. Reson. Imaging 2014;40:503–515 . © 2014 Wiley Periodicals, Inc .     

Conspicuity and evolution of lesions in Creutzfeldt-Jakob disease at diffusion-weighted imaging

BACKGROUND AND PURPOSE: Diffusion-weighted imaging can disclose distinct hyperintense lesions in Creutzfeldt-Jakob disease (CJD). However, these findings and chronologic changes of CJD at diffusion-weighted imaging have not been fully investigated. Our purpose was to assess the diagnostic value of diffusion-weighted imaging in depicting CJD-related lesions and in tracking the evolution of these lesions. We also compared the sensitivity of diffusion-weighted imaging in depicting CJD-related lesions to that of fluid-attenuated inversion recovery (FLAIR) imaging. METHODS: We reviewed findings in 13 patients with a diagnosis of CJD who underwent MR imaging, including diffusion-weighted imaging. Nine patients were initially examined within 4 months of onset of symptoms (early stage), and eight were examined 4 months or later (late stage). We evaluated four items: 1) distribution of lesions at diffusion-weighted imaging, 2) conspicuity of lesions at diffusion-weighted imaging and FLAIR imaging, 3) chronologic changes in lesions at diffusion-weighted imaging, and 4) chronologic changes in lesions revealed by apparent diffusion coefficient (ADC) maps. RESULTS: Patients had striatal lesions or cerebral cortical lesions or both. The thalamus was involved in only one patient, and the globus pallidus was spared in all patients. The sensitivity of diffusion-weighted imaging in depicting lesions was superior or at least equal to that of FLAIR imaging. Hyperintense lesions at diffusion-weighted imaging changed in extent and intensity over time. Unlike infarction, lesional ADC decreased for 2 weeks or longer. CONCLUSION: The progressively hyperintense changes in the striata and cerebral cortices at diffusion-weighted imaging are considered characteristic of CJD. Diffusion-weighted imaging may be useful for the early diagnosis of CJD.     

Systematic review of CT and MR perfusion imaging for assessment of acute cerebrovascular disease

BACKGROUND AND PURPOSE: Perfusion imaging sequences are an important part of imaging studies designed to provide information to guide therapy for treatment of cerebrovascular disease. The purpose of this study was to perform a meta-analysis of the medical literature on perfusion imaging to determine its role in clinical decision making for patients with acute cerebral ischemia.MATERIALS AND METHODS: We searched MEDLINE by using a strategy that combined terms related to perfusion imaging with terms related to acute cerebral ischemia and brain tumors. We identified 658 perfusion imaging articles and classified them according to the clinical usefulness criteria of Thornbury and Fryback. We found 59 articles with promise of indicating usefulness in clinical decision making. We devised and implemented a clinical decision making scoring scale more appropriate to the topic of acute cerebral ischemia.RESULTS: Several articles provided important insights into the physiologic processes underlying acute cerebral ischemia by correlation of initial perfusion imaging deficits with clinical outcome or ultimate size of the infarct. However, most articles showed relatively low relevance to influencing decisions in implementing treatment.CONCLUSION: Most perfusion imaging articles are oriented toward important topics such as optimization of imaging parameters, determination of ischemia penumbra, and prediction of outcome. However, information as to the role of perfusion imaging in clinical decision making is lacking. Studies are needed to demonstrate that use of perfusion imaging changes outcome of patients with acute cerebral ischemia.

This study is the culmination of work performed in response to a request for applications submitted by the Neuroradiology Education and Research Fund of the American Society of Neuroradiology (ASNR) for a systematic review of the medical literature regarding the usefulness of perfusion imaging in neuroradiology. The authors were charged with the task of examining the evidence for a substantive role for perfusion imaging in evaluation of the brain with a focus on understanding the place of perfusion imaging in medical decision making. We found that most published work has focused on 2 subjects, cerebrovascular disease and brain neoplasms, and 2 techniques, CT perfusion imaging and MR perfusion imaging. This study presents the results of our meta-analysis solely with regard to cerebrovascular disease. The results of the meta-analysis of perfusion imaging in imaging of brain tumors will be provided in a separate report.The goal of the meta-analysis was to determine the extent to which perfusion imaging figures affect clinical decision making and influence patient outcomes. It is important to note that the goal was not to establish whether perfusion imaging yields important information that advances our understanding of the physiologic processes of cerebral infarction or whether perfusion imaging might provide data that could determine likelihood of success of stroke therapy.     

Persistent hyperplastic primary vitreous involving the anterior eye.

The imaging features of persistent hyperplastic primary vitreous (PHPV) affecting the posterior eye are well known. We recently encountered a patient with the anterior variant of PHPV who had MR imaging of the orbits. We present the clinical and imaging findings of this unusual entity and discuss the therapeutic options available for its management.     

Value of dynamic MR imaging in assessing endometrial carcinoma involvement of the cervix

OBJECTIVE: The purpose of this study was to evaluate endometrial carcinoma involvement of the cervix using dynamic MR imaging compared with T2-weighted and contrast-enhanced T1-weighted MR imaging. SUBJECTS AND METHODS: In 42 patients with endometrial carcinoma, T2-weighted MR imaging using rapid acquisition with relaxation enhancement, dynamic MR imaging using gradient-echo sequences, and contrast-enhanced T1-weighted MR imaging using spin-echo sequences were performed before treatment. We evaluated patterns of enhancement in the cervix and tumor. In 39 of the 42 patients who underwent surgical treatment, we compared MR imaging findings with histologic results concerning cervical involvement. RESULTS: Enhancement of the cervical epithelium was greater than that of the tumor and cervical stroma on dynamic MR imaging in most patients. In assessing cervical involvement, the accuracy of T2-weighted, dynamic, and contrast-enhanced T1-weighted MR imaging was 85%, 95%, and 90%, respectively; no statistically significant difference was observed. False-positive cases on T2-weighted MR imaging were correctly identified as having no cervical involvement on dynamic MR imaging using the finding of continuous enhancement of the cervical epithelium. We found this finding to be reliable in assessing tumor involvement of the cervix. CONCLUSION: We believe that, in combination with T2-weighted MR imaging sequences, dynamic MR imaging is useful in assessing endometrial carcinoma involvement of the cervix.     

Meniscal abnormalities of the knee: 3DFT fast-scan GRASS MR imaging

The ability to use fast-scan techniques to obtain MR images without sacrificing diagnostic accuracy is a desirable goal in MR imaging. We describe a series of patients in whom fast-scan MR imaging was found to be equal to conventional spin-echo imaging in the detection and characterization of meniscal abnormalities. Thirty-five patients with suspected meniscal tears were studied with fast-scan imaging (3DFT-GRASS), and the results were compared with those of conventional spin-echo imaging. Three-millimeter contiguous sections through the entire knee were obtained in 5 min by using the 3DFT-GRASS technique. 3DFT-GRASS and spin-echo images agreed in all cases regarding the presence or absence of an abnormality and its degree of severity. We conclude that fast-scan 3DFT-GRASS MR imaging is useful when screening the knee for the presence of meniscal abnormalities.     

分子成像技术的研究进展

分子成像是新时代的医学成像,它可以无创性监测活体内的细胞和分子水平的生物学过程,其中包括核医学分子显像、磁共振分子成像、超声分子成像、光学分子成像和X射线分子成像等.目前,由于多学科融合的发展,多模式融合成像技术已成功用于临床,如PET-CT和PET-MRI.随着分子探针的发展和多模式融合成像技术的成熟,越来越多的分子...     

Musculoskeletal applications of flat-panel volume CT

Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).     

Optimization of parathyroid imaging by simultaneous dual energy planar and single photon emission tomography

BACKGROUND: Single photon emission tomography (SPET) gives valuable 3-dimensional information, but prolongs the time of imaging and increases the possibility of patient movement. We therefore investigated a method for the optimization of SPET. METHOD: Using an in-house fabricated thyroid/parathyroid neck phantom simultaneous dual energy (DE) 1223I/99mTc imaging to localize parathyroid glands was assessed both in planar and SPET modes. RESULTS: Experiments demonstrated improved spatial resolution and contrast for planar pinhole imaging compared to parallel collimation. For DE-SPET compared to planar pinhole imaging more glands in the phantom were visualized by the improved contrast. CONCLUSION: We conclude that DE-SPET for parathyroid imaging is feasible to aid the accurate localization of parathyroid adenomas. For planar imaging pinhole collimation is superior to parallel hole collimation.     

MRI in ankle tuberculosis: Review of 14 cases

We reviewed the MR imaging features of ankle tuberculosis and determined the role of MR in its diagnosis. A retrospective analysis of 14 cases of ankle tuberculosis imaged with MRI was performed. Plain radiographs were also reviewed where available, and the imaging characteristics were noted. We also reviewed the medical records in order to assess the impact of the imaging findings on management of these patients. Magnetic resonance imaging is extremely helpful for detection, mapping the extent and resolution of the disease. It can identify cases, enables early institution of antituberculous chemotherapy and might obviate the need for surgery.     

Localized fibrous tumor of the liver: imaging findings

We report the imaging of a localized fibrous tumor of the liver, focusing on color Doppler US, CT, MR imaging, and angiographic findings. We discuss the differential diagnosis of such a rare, benign lesion of the liver. Detailed imaging of this tumor has not been reported in the literature previously. Received 25 November 1996; Revision received 10 April 1997; Accepted 17 June 1997     

MRI of conjoined twins illustrating advances in fetal imaging

Complex congenital fetal abnormalities are optimally evaluated with both ultrasound and magnetic resonance imaging. With the advent of ultrafast imaging sequences, fetal imaging has significantly improved. We present two cases of conjoined thoracoomphalopagus twins to discuss this unusual anomaly and to illustrate the recent advances in magnetic resonance imaging of the fetus.     

Fast magnetic resonance imaging of the lung.

The impact of fast MR techniques developed for MR imaging of the lung will soon be recognized as equivalent to the high-resolution technique in chest CT imaging. In this article, the difficulties in MR imaging posed by lung morphology and its physiological motion are briefly introduced. Then, fast MR imaging techniques to overcome the problems of lung imaging and recent applications of the fast MR techniques including pulmonary perfusion and ventilation imaging are discussed. Fast MR imaging opens a new exciting window to multi-functional MR imaging of the lung. We believe that fast MR functional imaging will play an important role in the assessment of pulmonary function and disease process.     

Fast MR imaging: techniques and clinical applications

Fast MR imaging has matured in the past few years and is now of established value for several aspects of clinical MR imaging. The initial impetus for rapid imaging was to reduce scan times. Today its usefulness includes reducing motion artifacts, improved contrast per unit time, three-dimensional (3-D) imaging, real-time imaging, cine-mode imaging, and flow imaging. The focus of this review is on short-TR steady-state gradient-echo imaging. We discuss the basic sequence design of the mainstream fast techniques. Many important applications exist, including gadopentetate dimeglumine-enhanced MR imaging of the brain and spine, subsecond imaging of real-time applications, myelographic imaging of the spine, cardiac cine-mode imaging; 3-D musculoskeletal (knee) imaging, 3-D pituitary imaging; two-dimensional and 3-D body imaging; 3-D carotid and intravascular imaging, and reformatting 3-D images into arbitrary planes.     

Multiple-spin-echo imaging with a 2D Fourier method

In 2D Fourier imaging the normal Carr-Purcell multiple-echo sequence generally leads to center line and mirror artifacts caused by imperfect rotations by the rf pulses. We describe a method to avoid these distortions using a phase alternating-phase shift (PHAPS) sequence which also allows multiple-slice and multiple-echo imaging at the same time. Measuring phantoms with calibrated T2 values, we have shown that the PHAPS imaging sequence leads to an accuracy of quantitative T2 determinations of better than 10%. Contrast-enhanced images are presented which we calculated from multiple-echo images and extrapolated to arbitrary echotimes, including negative ones. We believe that these improvements in T2 imaging will result in a significant reduction of patient investigation time in magnetic resonance imaging.     

MR imaging and diffusion-weighted imaging changes in metronidazole (Flagyl)-induced cerebellar toxicity

We describe a case demonstrating reversible MR imaging findings, including diffusion-weighted imaging changes in association with metronidazole (Flagyl) toxicity. The diagnosis of metronidazole toxicity was made clinically and supported by the MR imaging findings. Quantitative apparent diffusion coefficient (ADC) maps demonstrated edema with associated increased ADC values within the dentate nuclei of the cerebellum on initial imaging. Follow-up imaging performed 8 weeks after cessation of metronidazole therapy demonstrated resolution of imaging findings, including diffusion changes.     

Breast MRI for evaluating patients with metastatic axillary lymph node and initially negative mammography and sonography.

OBJECTIVE: We wanted to investigate the ability of breast MR imaging to identify the primary malignancy in patients with axillary lymph node metastases and initially negative mammography and sonography, and we correlated those results with the conventional imaging. MATERIALS AND METHODS: From September 2001 to April 2006, 12 patients with axillary lymph node metastases and initially negative mammography and sonography underwent breast MR imaging to identify occult breast carcinoma. We analyzed the findings of the MR imaging, the MR-correlated mammography and the second-look sonography. We followed up both the MR-positive and MR-negative patients. RESULTS: MR imaging detected occult breast carcinoma in 10 of 12 (83%) patients. Two MR-negative patients were free of carcinoma in the ipsilateral breast during their follow-up period (39 and 44 months, respectively). In nine out of 10 patients, the MR-correlated mammography and second-look sonography localized lesions that were not detected on the initial exam. All the non-MR-correlated sonographic abnormalities were benign. CONCLUSION: Breast MR imaging can identify otherwise occult breast cancer in patients with metastatic axillary lymph nodes. Localization of the lesions through MR-correlated mammography and second-look sonography is practically feasible in most cases.     

Magnetic resonance imaging of intraspinal epidermoid cyst: a case report

Intraspinal epidermoid cysts are considered rare lesions. We report such a case in a 12-year-old boy that was diagnosed by magnetic resonance imaging. The magnetic resonance imaging characteristics of the lesion and the importance of proper imaging sequences are discussed.