Understanding the heart: CT and MRI for coronary heart disease

Methods of noninvasive evaluation of coronary artery disease-including multidetector row computed tomography, electron beam computed tomography, magnetic resonance imaging, and nuclear studies (single photon emission computed tomography, positron emission tomography)-are reviewed.     

Magnetic resonance approaches and recent advances in myocardial perfusion imaging

Myocardial perfusion imaging identifies the presence of coronary artery stenoses and defines the functional significance of those lesions. Single photon emission computed tomography and positron emission tomography have established roles. Cardiac magnetic resonance is evolving as a promising new modality in the evaluation of myocardial perfusion. This article summarizes the current capability and recent advancements in magnetic resonance perfusion imaging.     

Primary hepatic carcinoid tumour: a detailed account of imaging findings

Primary hepatic carcinoid tumours are very rare and less than 60 cases have been reported in the literature. This study reports a 35-year-old female with 2 synchronous primary hepatic carcinoid tumours in her right hepatic lobe. She was examined with various imaging investigations including ultrasound scan, computed abdominal tomography, magnetic resonance imaging, mesenteric angiography and positron emission tomography. She underwent right hepatectomy and the lesions were proven to be carcinoid tumours. She has been free of disease for more than 5 years of follow-up and the diagnosis of primary hepatic carcinoid tumour is suggested.     

The acute inflammatory response to myocardial infarction: imaging with indium-111 labelled autologous neutrophils

The uptake of indium-111 labelled neutrophils was examined in 30 patients with acute myocardial infarction by planar imaging and single photon emission computed tomography. The time from venepuncture to reinjection of the autologous labelled neutrophils was less than 2.5 hours and imaging was carried out 24 hours later. Twenty three patients had a positive uptake of neutrophils in the myocardium and imaging was improved by single photon emission computed tomography. There was a significant difference between the intervals from the onset of chest pain to injection of labelled neutrophils between patients with positive and negative images; early reinjection was more likely to produce a positive image. Indeed, all nine patients reinjected within 18 hours of the onset of symptoms had positive images. The results suggest that the stimulus for activation and migration of neutrophils is transient; this is an important factor if neutrophil release products play a role in cell damage after coronary occlusion.     

The acute inflammatory response to myocardial infarction: imaging with indium-111 labelled autologous neutrophils.

The uptake of indium-111 labelled neutrophils was examined in 30 patients with acute myocardial infarction by planar imaging and single photon emission computed tomography. The time from venepuncture to reinjection of the autologous labelled neutrophils was less than 2.5 hours and imaging was carried out 24 hours later. Twenty three patients had a positive uptake of neutrophils in the myocardium and imaging was improved by single photon emission computed tomography. There was a significant difference between the intervals from the onset of chest pain to injection of labelled neutrophils between patients with positive and negative images; early reinjection was more likely to produce a positive image. Indeed, all nine patients reinjected within 18 hours of the onset of symptoms had positive images. The results suggest that the stimulus for activation and migration of neutrophils is transient; this is an important factor if neutrophil release products play a role in cell damage after coronary occlusion.     

Comparison of (11)C-acetate positron emission tomography and (67)Gallium citrate scintigraphy in patients with hepatocellular carcinoma.

AIMS: Nuclear imaging may have an increasing role in the diagnosis of hepatocellular carcinoma (HCC). The aim of this study was to compare prospectively the Gallium-67 citrate ((67)Ga) scintigraphy results with those obtained by positron emission tomography (PET) using (11)C-acetate in patients with HCC. METHODS: We prospectively analysed 21 patients (mean age, 64+/-11 years) with histopathologically verified HCC undergoing (11)C-acetate PET and (67)Ga scintigraphy. (67)Ga scans were not performed in three of these 21 patients due to the exacerbation of the disease. Whole-body (11)C-acetate PET were performed following intravenous injection of 850 MBq of (11)C-acetate. For (67)Ga scintigraphy, whole-body, planar and single photon emission computed tomography imaging acquisitions were performed after intravenous application of a mean dose of 189 MBq (67)Ga. RESULTS: (67)Ga scintigraphy found abnormalities only in 10 of 18 patients (56%) and detected 22 of 46 clinically involved sites (48%); it was false-positive in two patients. (11)C-acetate PET found abnormalities in 14 of 18 patients (78%) and detected 36 of 46 clinical lesions (78%); it was false-positive in one patients. In one patient with left supraclavicular lymph node metastases, neither the (67)Ga scintigraphy nor the conventional computed tomography have shown the lesions, which were clearly demonstrated by the (11)C-acetate PET. CONCLUSION: Our results indicate significantly higher sensitivity and specificity of (11)C-acetate PET than (67)Ga scan in detection of HCC lesions. This study suggests that imaging with (11)C-acetate PET might play a potential role in the diagnostic workup of patients with HCC.     

Radiological and nuclear medicine imaging of gastroenteropancreatic neuroendocrine tumours

Neuroendocrine tumours (NETs) comprise a heterogeneous group of neoplasms with very varying clinical expression. A functioning NET, for instance in the pancreas, may be very small and yet give rise to severe endocrine symptoms whereas a patient with a small bowel tumour may present with diffuse symptoms and disseminated disease with a palpable bulky liver. Imaging of NETs is therefore challenging and the imaging needs in the various patients are diverse. The basic modalities for NET imaging are computed tomography (CT) or magnetic resonance imaging (MRI) in combination with somatostatin receptor imaging (SMI) by scintigraphy with 111In-labelled octreotide (OctreoScan) or more recently by positron emission tomography (PET) with 68Ga-labelled somatostatin analogues. In this review these various morphological and functional imaging modalities and important methodological aspects are described. Imaging requirements for the various types of NETs are discussed and typical image findings are illustrated.     

Estimating the size of myocardial infarction by magnetic resonance imaging.

OBJECTIVE--To develop a method to measure myocardial infarct size by magnetic resonance imaging and to compare the results with pyrophosphate scanning by single photon emission computed tomography. DESIGN--All patients underwent magnetic resonance imaging and pyrophosphate scanning 5-7 days after the onset of symptoms. Both measurements of infarct size were compared with the release of creatine kinase MB and with ventricular performance estimated by radionuclide ventriculography. PATIENTS--19 patients (age 40-68 years) who had sustained their first uncomplicated myocardial infarction and who had not been treated with thrombolytic therapy. RESULTS--The site of infarction was clearly shown by both imaging techniques and was identical in each patient. The volume of infarcted tissue measured by magnetic resonance imaging agreed well with the infarct size measured by single photon emission tomography (mean difference 2.7 cm3). Correlations of both imaging techniques with the release of creatine kinase MB were best when total release rather than peak release was used. Both imaging techniques correlated closely with the subsequent ventricular performance. CONCLUSIONS--Magnetic resonance imaging after acute infarction allows measurement of infarct size and this may prove useful in assessing new treatments designed to salvage myocardium.     

Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis

Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.     

Detecting abnormal regional cerebral blood flow in patients with primary Sjögren's syndrome by technetium-99m ethyl cysteinate dimer single photon emission computed tomography of the brain—a preliminary report

Technetium-99m ethyl cysteinate dimer (Tc-99m ECD) brain single photon emission computed tomography (SPECT) was used to detect abnormal regional cerebral blood flow (rCBF) in 32 female patients with primary Sjögren's syndrome (PSS) showing definite neuropsychiatric symptoms/signs and normal brain magnetic resonance imaging (MRI) findings. It demonstrated hypoperfusion brain lesions in 18 (56.3%) of the patients, most frequently in the parietal lobes, and appears to be a sensitive tool for this clinical application.     

Clinical applications of SPECT

The clinical use of single photon emission computed tomography (SPECT) has grown steadily over the last decade. SPECT is now an essential technique for certain studies such as cerebral blood flow imaging. Many other common nuclear medicine studies give better results when they are performed with SPECT. These include myocardial perfusion imaging with thallium-201 or the new technetium-99m perfusion agents, myocardial infarct imaging with infarct-avid agents, imaging of tumors or infections with agents such as gallium-67 or indium-111 WBC's, and certain cases of bone imaging. Still other studies such as liver/spleen imaging, most brain studies, and perhaps renal imaging may benefit from SPECT even though planar imaging gives satisfactory results. Future developments in 3D display techniques and faster computers may extend the clinical usefulness of SPECT to other areas such as pulmonary perfusion imaging and gated cardiac blood pool imaging.Abbreviations SPECT single photon emission computed tomography - WBC white blood cells - 3D three dimensional     

帕金森病的影像学检查诊断进展

随着医学影像学技术的快速发展以及从影像学角度对帕金森病(PD)认识的不断进步,以单光子发射计算机断层显像(SPECT/CT)、正电子发射计算机断层显像(PET)、核磁共振(MRI)、经颅超声成像(TCS)等为代表的功能成像技术,可显示脑血流、代谢、神经递质、转运体、受体、黑质回声改变,对PD的诊断均有各自的优越性。     

111In monoclonal antimyosin antibody imaging: imaging of myocardial infarction and myocarditis

A new scintigraphic method to detect myocardial necrosis has been developed using antimyosin monoclonal antibody Fab labeled with indium-111. Using this method, we studied 35 patients with myocardial infarction, 5 patients with myocarditis and 3 patients with angina pectoris. 111In antimyosin Fab was administered intravenously and antimyosin images were recorded by planar and single photon emission computed tomography (SPECT) 48 hours after injection. Planar images showed discrete localization of 111In antimyosin in 25 of 26 patients within 14 days after the onset of acute myocardial infarction. In 14 of these patients creatine kinase, glutamic oxaloacetic transaminase and lactic dehydrogenase had already normalized. Positive scans were also obtained in 6 of 12 patients between the third week to the ninth year after the onset of the disease. Three patients with acute myocarditis had positive scans 2 and 4 weeks after the onset of the disease. Thus, 111In antimyosin imaging may be a useful noninvasive method for the diagnosis of coronary diseases and myocarditis. Although the mechanism of persistent positive antimyosin images in the chronic stage remains to be clarified, 111In antimyosin scintigraphy holds potential promise as a non-invasive method for the detection of myocardial injury in the subacute to chronic stage as well as in the acute stage.     

活体生物发光成像技术及其在消化道研究领域中的应用

活体生物发光成像技术作为一种非放射性、非损伤性、高灵敏特异性、实时动态的分子生物学检测技术,实现了在活体内对生物学反应实时、原位、动态和无损伤的观察,相比CT、MRI、PET和SPECT等传统影像学成像技术,活体发光成像技术显示出了巨大的优越性.活体生物发光成像技术已成为检测小动物体内分子及细胞事件的强有力工具,越来越广泛地应用于基础生命科学的研究领域.近年来,生物发光成像技术因其高度的特异性和敏感性,在肿瘤学的研究领域也逐渐得以应用,并显示出了良好的应用前景.本文就活体生物发光成像技术的成像特点、技术原理及其在消化道研究领域的应用做一综述.     

Recent advances in radiological and radionuclide imaging and therapy of neuroendocrine tumours

Neuroendocrine tumours (NETs) constitute a heterogeneous group of tumours that are able to express cell membrane neuroamine uptake mechanisms and/or specific receptors, such as somatostatin receptors, which can be of great value in the localization and treatment of these tumours. Scintigraphy with (111)In-pentetreotide has become one of the most important imaging investigations in the initial identification and staging of gastro-enteropancreatic (GEP) tumours, whereas helical computed tomography (CT), magnetic resonance imaging (MRI), endoscopic and/or peri-operative ultrasonography are used for the precise localization of GEPs and in monitoring their response to treatment. Scintigraphy with (123)I-MIBG (meta-iodobenzylguanidine) is sensitive in the identification of chromaffin cell tumours, although scintigraphy with (111)In-pentetreotide may also have a role in the localization of malignant chromaffin cell tumours and medullary thyroid carcinoma; for further localization and monitoring of the response to treatment both CT and MRI are used with high diagnostic accuracy. More recently, positron emission tomography (PET) scanning is being increasingly used for the localization of NETs, particularly when other imaging modalities have failed, although its precise role and utility remain to be defined. Surgery is still the usual initial therapeutic, and only curative, modality of choice; however, the majority of NETs will require further treatment with somatostatin analogues and/or interferon; chemotherapy may be used for progressive and highly aggressive NETs, but its role has not been clearly defined. For those NETs that demonstrate uptake to a diagnostic scan with (123)I-MIBG or (111)In-octreotide, therapy with radionuclides such as (131)I-MIBG or (111)In/(90)Y-octreotide or other isotopes, presents a further evolving therapeutic modality.     

Hybrid ultrasound imaging techniques（fusion imaging）

Visualization of tumor angiogenesis can facilitate noninvasive evaluation of tumor vascular characteristics to supplement the conventional diagnostic imaging goals of depicting tumor location,size,and morphology.Hybrid imaging techniques combine anatomic [ultrasound,computed tomography(CT),and/or magnetic resonance imaging(MRI)] and molecular(single photon emission CT and positron emission tomography) imaging modalities.One example is real-time virtual sonography,which combines ultrasound(grayscale,colour D...     

Gallium-67 myocardial imaging for the detection of myocarditis in the acute phase of Kawasaki disease (mucocutaneous lymph node syndrome): the usefulness of single photon emission computed tomography

Myocardial imaging with gallium-67 citrate was used to detect myocarditis in 46 consecutive infants and children (31 boys and 15 girls, mean age 21 months) with Kawasaki disease. In all of them planar imaging (group A) was performed at 6 hours and at 48 or 72 hours after the intravenous administration of a mean (SD) dose of gallium-67 citrate (0.07 (0.02) mCi/kg). Thirty four patients (24 boys and 10 girls, mean age 21 months) also had single photon emission computed tomography imaging (group B) soon after planar imaging. The patients had been ill for from 5 days to 16 days (mean (SD) 10.5 (2.4) days in group A and 10.6 (3.0) days in group B). The colour images obtained at 48 or 72 hours were positive in 41% of group A and in 64% of group B. Among the patients with clinically suspected myocarditis, 63% in group A and 80% in group B had positive myocardial images. Single photon emission computed tomography imaging permitted the identification of tracer in the myocardium, the pericardium only, or in the heart chambers. Myocardial imaging with gallium-67 citrate, especially when used with single photon emission computed tomography imaging, is useful for the detection of myocarditis in the acute phase of Kawasaki disease.     

Gallium-67 myocardial imaging for the detection of myocarditis in the acute phase of Kawasaki disease (mucocutaneous lymph node syndrome): the usefulness of single photon emission computed tomography.

Myocardial imaging with gallium-67 citrate was used to detect myocarditis in 46 consecutive infants and children (31 boys and 15 girls, mean age 21 months) with Kawasaki disease. In all of them planar imaging (group A) was performed at 6 hours and at 48 or 72 hours after the intravenous administration of a mean (SD) dose of gallium-67 citrate (0.07 (0.02) mCi/kg). Thirty four patients (24 boys and 10 girls, mean age 21 months) also had single photon emission computed tomography imaging (group B) soon after planar imaging. The patients had been ill for from 5 days to 16 days (mean (SD) 10.5 (2.4) days in group A and 10.6 (3.0) days in group B). The colour images obtained at 48 or 72 hours were positive in 41% of group A and in 64% of group B. Among the patients with clinically suspected myocarditis, 63% in group A and 80% in group B had positive myocardial images. Single photon emission computed tomography imaging permitted the identification of tracer in the myocardium, the pericardium only, or in the heart chambers. Myocardial imaging with gallium-67 citrate, especially when used with single photon emission computed tomography imaging, is useful for the detection of myocarditis in the acute phase of Kawasaki disease.     

Advances in imaging for assessment of ischemic heart disease

Cardiac imaging techniques continue to develop for the noninvasive detection and evaluation of patients with coronary artery disease. These techniques include single photon and positron emission tomography along with computed tomography and magnetic resonance imaging. The new myocardial perfusion tracers 99mTc-hexakis-2-methoxyisobutyl-isonitrile and 99mTc-teboroxime have recently come into general use for these purposes, and their role alongside that of more traditional agents is currently being defined using new imaging protocols and instrumentation. 99mTc-hexakis-2-methoxyisobutyl-isonitrile has also been documented as an important research tool for evaluating both at-risk myocardium and the degree of subsequent myocardial salvage following reperfusion therapies for acute myocardial infarction. Antimyosin antibody imaging is another emerging approach in the evaluation of patients with acute myocardial infarction. Metabolic imaging with 18F-fluoro-2-deoxyglucose using positron emission tomography to detect myocardial segments with compromised blood flow but preserved glucose metabolism is currently the best noninvasive method of identifying viable myocardium in patients with left ventricular dysfunction who may benefit from revascularization. Insights from these studies have led to development of the current 201Tl stress-rest reinjection protocols for viability evaluation using single photon emission computed tomography. Positron emission tomography, in combination with blood flow tracers using kinetic modeling, provides accurate estimates of coronary blood flow and flow reserve. The use of these new imaging techniques will allow increasingly accurate evaluation of patients with suspected and proven coronary artery disease in the future.     

Localisation of neuroendocrine tumours of the upper gastrointestinal tract.

In order to localise neuroendocrine tumours of the foregut type (that is, of the stomach, duodenum, and pancreas), 18 patients were studied prospectively by endoscopic ultrasonography, computed tomography, transabdominal ultrasonography, magnetic resonance imaging, and somatostatin receptor scintigraphy. These 18 patients had a total of 25 primary tumour lesions which were verified histologically in tissue obtained by surgery or by ultrasound or endoscopy guided biopsy. Tumours were found in the stomach (n = 1), duodenum (n = 6), pancreas (n = 17), and liver (n = 1). Endoscopic ultrasonography had the highest sensitivity for tumour detection, followed by somatostatin receptor scintigraphy, computed tomography, transabdominal ultrasonography, and magnetic resonance imaging (88%, 52%, 36%, 32%, and 24% respectively). Endoscopic ultrasonography was especially sensitive in tumours smaller than 2 cm in diameter (88% v somatostatin receptor scintigraphy 35%; computed tomography 12%; transabdominal ultrasonography 6%; and magnetic resonance imaging 0%). Of 17 tumours located in the pancreas, endoscopic ultrasonography showed a sensitivity of 94% (somatostatin receptor scintigraphy 47%; computed tomography 47%; transabdominal ultrasonography 41%; and magnetic resonance imaging 29%). Of eight extrapancreatic tumours, six were identified by endoscopic ultrasonography, five by somatostatin receptor scintigraphy, and only one by computed tomography, transabdominal ultrasonography, and magnetic resonance imaging. One neuroendocrine tumour that was not detected by endoscopic ultrasonography was correctly identified by somatostatin receptor scintigraphy. Endoscopic ultrasound allowed correct determination of the tumour size and tumour spread into parapancreatic structures, especially the large vessels (T stage), in all 14 patients operated upon. The lymph node stage (N stage) was correctly determined in 10 of these 14 patients. In summary, endoscopic ultrasonography and somatostatin receptor scintigraphy were the most sensitive imaging methods for the localisation of these tumours and should be used as early diagnostic procedures to accurately stage neuroendocrine tumours of the foregut type.