F-18 fluoro deoxyglucose SPECT for assessment of myocardial viability

Identification of myocardial viability in hypokinetic segments is important in patients with ischemic cardiomyopathy because systolic dysfunction improves with revascularization. Positron emission tomography (PET) F-18 fluoro deoxyglucose (FDG) uptake has been demonstrated as an accurate indicator of metabolically active and thus viable myocardium. F-18 FDG single photon emission computed tomography (SPECT) has recently been introduced and offers a technically easier and less costly alternative to PET imaging for determination of myocardial viability. A body of literature demonstrates that F-18 FDG SPECT can reliably be performed with SPECT hardware equipped with 511-keV collimators, which provides an accurate assessment of myocardial viability. F-18 FDG SPECT offers data similar to those offered by F-18 FDG PET and compares favorably with other imaging modalities, including rest-redistribution and stress-reinjection thallium-201 myocardial perfusion imaging, gated technetium 99m SPECT, and low-dose dobutamine echocardiography.     

18 F-FDG PET显像与99Tcm-MDP全身骨显像诊断肿瘤远处转移的比较

目的　评价18F 脱氧葡萄糖 (FDG)PET肿瘤显像与99Tcm 亚甲基二膦酸盐 (MDP)全身骨显像对检出骨和远处转移的价值。方法　对 16例恶性肿瘤放化疗后的患者进行18F FDGPET显像和99Tcm MDP全身骨显像 ,并对两种结果进行了比较。结果　 16例肿瘤患者中18F FDGPET显像皆阳性 ,其中 14例患者有远处转移 ,转移病灶共 62处 ,其中骨转移病灶 2 0处 ;在全身骨显像中 ,11例有局限性异常放射性浓聚 ,其中 2例为单一病灶 ,9例为多发病灶 ,共检出病灶 5 7处 ,另 5例骨显像正常。结论　18F FDGPET对恶性肿瘤的诊断具有较高的准确性和特异性 ,但对骨转移灶的诊断价值相对较差 ;99Tcm MDP显像阴性或单一病灶的可疑转移瘤患者有必要进行18F FDGPET检查 ,以明确诊断其他远处转移灶     

Positron emission tomography and single photon emission computed tomography in epilepsy care

Radiopharmaceutical brain imaging is clinically applied in planning resective epilepsy surgery. Cerebral sites of seizure generation-propagation are highly associated with regions of hyperperfusion during seizures, and with glucose hypometabolism interictally. For surgical planning in epilepsy, the functional imaging modalities currently established are ictal single photon emission computed tomography (SPECT) with [(99m)Tc]technetium-hexamethylpropyleneamine oxime (HMPAO) or with [(99m)Tc]technetium-ethylene cysteine dimer (ECD), and interictal positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxyglucose (FDG). Ictal SPECT and interictal FDG PET can be used in presurgical epilepsy evaluations to reliably: (1) determine the side of anterior temporal lobectomy, and in children the area of multilobar resection, without intracranial electroencephalographic recording of seizures; (2) select high-probability sites of intracranial electrode placement for recording ictal onsets; and, (3) determine the prognosis for complete seizure control following anterior temporal lobe resection. Coregistration of a patient's structural (magnetic resonance) and functional images, and statistical comparison of a patient's data with a normal data set, can increase the sensitivity and specificity of these SPECT and PET applications to the presurgical evaluation.     

Nuclear medicine imaging of lung cancer

Although nuclear medicine imaging is still widely under-appreciated and underused by the medical and radiologic communities, FDG PET imaging and Tc 99m depreotide SPECT imaging are safe, cost-effective methods with advantages over CT and other imaging methods in the diagnosis and management of patients suspected or known to have lung cancer. Physicians involved in the care of these patients should familiarize themselves with both of these relatively new nuclear medicine imaging procedures. Both F-18 FDG PET imaging and Tc 99m depreotide SPECT imaging have a high degree of sensitivity, specificity, overall accuracy, and both PPV and NPV in the management of patients with a solitary pulmonary nodule. Nuclear imaging with either of these agents provides a noninvasive, cost-effective method to select patients for aggressive intervention without contributing to increased morbidity. There has not been a direct comparison of these two techniques in terms of their relative role and cost-effectiveness in the management of patients with a solitary pulmonary nodule. Both methods have incremental value over CT imaging in selecting patients with solitary pulmonary nodules either for invasive biopsy or for thoracotomy. To date, only FDG PET has been proved to have additional application in: 1. Improving the staging of patients by identifying or excluding mediastinal disease. Some authors are reluctant at the present time to deny patients an opportunity for curative resection based on the finding of foci of increased metabolism in the mediastinum (characterized by increased FDG activity) because there are occasional false-positive studies. They propose, however, that a negative study justifies a surgical approach (and an opportunity for cure) regardless of the findings on CT. 2. Evaluation of therapy and early detection of recurrence by using FDG PET imaging as a monitoring procedure. Tc 99m depreotide may have a role also in these other clinical indications for imaging in patients with lung carcinoma. It is too soon, however, to know if Tc 99m depreotide SPECT imaging, properly performed, can mimic the success of FDG PET in the detection or exclusion of mediastinal metastases, evaluating the response to therapy, and the early detection of recurrent disease during post-therapeutic monitoring.     

Estimation of myocardial perfusion and viability using simultaneous 99mTc-tetrofosmin--FDG collimated SPECT.

This study was designed to elucidate the usefulness of crosstalk correction for dual-isotope simultaneous acquisition (DISA) with 99mTc-tetrofosmin and FDG in estimating myocardial perfusion and viability. METHODS: Eighteen patients with coronary artery disease were studied. First, SPECT was performed with a low-energy high-resolution collimator after a single injection of 99mTc-tetrofosmin (single 99mTc-tetrofosmin). Second, PET and DISA with an ultra-high-energy collimator were performed after glucose loading and an injection of FDG. DISA was designed to operate with simultaneous 3-channel acquisition, and weighted scatter correction of crosstalk from the 18F photopeak to the 99mTc photopeak was performed by modification of an existing dual-window technique. The FDG SPECT images were compared with the images obtained by PET. Both crosstalk-corrected and uncorrected 99mTc-tetrofosmin images were generated and compared with the single 99mTc-tetrofosmin images. RESULTS: Regional percentage uptake of FDG agreed well between DISA and PET. However, regional percentage uptake of 99mTc-tetrofosmin was generally higher on the uncorrected 99mTc-tetrofosmin images than on the single 99mTc-tetrofosmin images, especially in areas of low flow (percentage count of 99mTc-tetrofosmin > or = 50%). The crosstalk correction contributed to improving the agreement between regional percentage uptakes and significantly improved the detectability of myocardial perfusion-metabolism mismatching. CONCLUSION: With 3-channel acquisition and weighted-scatter correction of crosstalk from the 18F photopeak to the 99mTc photopeak, DISA with 99mTc-tetrofosmin and FDG is feasible for assessing regional myocardial perfusion and viability.     

Characterization of septal penetration in 511 keV SPECT

BACKGROUND: Single photon emission computed tomography (SPECT) with 511 keV photons is a challenging modality and collimators for this purpose require trade-offs among resolution, sensitivity and septal penetration. While PET is the modality of choice for imaging at 511 keV, there are some procedures, e.g., dual-isotope imaging, in which 511 keV SPECT has a role. AIM: To measure the imaging properties of a VPC-93 SPECT collimator designed for imaging at 511 keV and to isolate the effects of septal penetration. METHODS: NaI gamma camera projection images of (18)F (511 keV) and (99m)Tc (140 keV) point sources were measured and the corresponding modulation transfer functions calculated. The projection images were reconstructed via filtered back-projection to obtain the tomographic three-dimensional (3-D) point spread function. Differences between the 511 and 140 keV results were attributed mainly to septal penetration. Contrast measurements were made separately using (18)F and (99m)Tc of a 20 cm phantom containing hot spheres and a warm background. Both isotopes were also used in imaging studies of a 3-D Hoffman brain phantom. RESULTS: Reconstructed 511 keV point source images were spatially extended with more than half of the total reconstructed counts appearing away from the point source region. The number of false counts contained in the image as a function of distance from the true source location remains approximately constant for large distances out to at least 14 cm. Septal penetration results in a rapid roll-off with spatial frequency of collimator response. The response of the collimator to 511 keV photons falls to half of its 0-frequency response at 0.03 cm(-1). For 140 keV photons this value is 0.20 cm(-1). A result is reduced image contrast as measured in the phantom sphere studies. Septal penetration causes image degradation through large-scale blurring. Image noise characteristics are modified and correlations are extended into many transaxial planes. CONCLUSIONS: Both 2-D and 3-D point spread functions for 511 and 140 keV photons using the VPC-93 collimator have been measured. Septal penetration unfavourably affects image resolution and changes image noise characteristics. Without compensation, the effects of septal penetration are readily apparent in images of real objects.     

不同能量放射性核素在PET/CT及SPECT采集中的相互影响

目的 利用模型探讨99TcmO4-与18F-氟脱氧葡萄糖(FDG)在图像采集中的相互影响,讨论同一患者是否可以同日分别采用PET/CT及SPECT两种仪器行高低两种能量放射性核素显像.材料与方法 利用统一规格、相同容积( 500ml)的5个塑料瓶(编号A、B、C、D、E),其内均注入500ml蒸馏水制作成模型.A瓶注入0.5mCi 18F-FDG行PET/CT显像;B瓶注入1mCi99TcmO4-行SPECT显像;C瓶内同时注入混合好的0.5mCi18F-FDG和1mCi99TcmO4-;D瓶内先注入1mCi99TcmO4-后再注入0.5mCi18F-FDG;E瓶先注入0.5mCi18F-FDG后再注入1mCi99TcmO4-.然后对C、D、E瓶分别行PET/CT显像和SPECT显像,并判断图像效果.结果 A瓶PET/CT显像和B瓶SPECT显像图像效果为1级;C、D瓶SPECT及PET/CT显像图像均为2级;E瓶SPECT显像图像为3级,PET/CT显像图像为1级.结论 同时加入18F-FDG和99TcmO4-对PET/CT和SPECT图像质量均有影响.先加入18F-FDG后加入99TcmO4-对PET/CT图像质量影响小,但SPECT图像不能分辨.先加入99TcmO4-后加入18F-FDG对PET/CT和SPECT图像质量均有影响.     

18-Fluorodeoxyglucose imaging with positron emission tomography and single photon emission computed tomography: cardiac applications

The assessment of myocardial viability has become an important aspect of the diagnostic and prognostic work-up of patients with ischemic cardiomyopathy. Although revascularization may be considered in patients with extensive viable myocardium, patients with predominantly scar tissue should be treated medically or evaluated for heart transplantation. Among the many viability tests, noninvasive assessment of cardiac glucose use (as a marker of viable tissue) with F18-fluorodeoxyglucose (FDG) is considered the most accurate technique to detect viable myocardium. Cardiac FDG uptake has traditionally been imaged with positron emission tomography (PET). Clinical studies have shown that FDG-PET can accurately identify patients with viable myocardium that are likely to benefit from revascularization procedures, in terms of improvement of left ventricular (LV) function, alleviation of heart failure symptoms, and improvement of long-term prognosis. However, the restricted availability of PET equipment cannot meet the increasing demand for viability studies. As a consequence, much effort has been invested over the past years in the development of 511-keV collimators, enabling FDG imaging with single-photon emission computed tomography (SPECT). Because SPECT cameras are widely available, this approach may allow a more widespread use of FDG for the assessment of myocardial viability. Initial studies have directly compared FDG-SPECT with FDG-PET and consistently reported a good agreement for the assessment of myocardial viability between these 2 techniques. Additional studies have shown that FDG-SPECT can also predict improvement of LV function and heart failure symptoms after revascularization. Finally, recent developments, including coincidence imaging and attenuation correction, may further optimize cardiac FDG imaging (for the assessment of viability) without PET systems.     

Value and limitation of myocardial fluorodeoxyglucose single photon emission computed tomography using ultra-high energy collimators for assessing myocardial viability

Single photon emission computed tomography (SPECT) using ultra-high energy collimators permits wide clinical application of (18)F-fluorodeoxyglucose (FDG) imaging without the use of expensive positron emission tomography (PET) cameras. This study was designed to evaluate the value of FDG SPECT using ultra-high energy collimators in assessing myocardial viability compared with FDG PET on a regional basis. We prospectively studied 33 patients with ischaemic heart disease. The patients were injected with 555 MBq of FDG under a hyperinsulinaemic glucose clamp, and FDG PET was performed 40 min later. FDG SPECT using ultra-high energy collimators was performed immediately after FDG PET. The images of the left ventricular myocardium were divided into nine segments and the regional defect score was assessed visually using a four-point scale (0=normal to 3=defect). Regional FDG uptake (%uptake) was quantitatively analysed using polar maps. In 297 segments of all the 33 patients, agreement between the defect scores based on FDG SPECT images and those based on FDG PET images was 70%, and agreement within one rank was 96% (kappa value=0.52). The %uptake based on FDG SPECT images significantly correlated with that based on FDG PET images (r=0.77, P<0.01). However, the defect scores in the inferior wall based on FDG SPECT images were higher (1.41+/-1.14) than those based on FDG PET images (1.06+/-1.12, P<0.01). When the viable region is defined as %uptake > or =50% in FDG PET studies, the optimal cut-off level of %uptake based on FDG SPECT images was 60% in the anterior wall, apex, septum and lateral wall (accuracies, 97%, 93%, 96% and 99%, respectively), and 45% in the inferior wall (accuracy, 99%). It is concluded that FDG SPECT using ultra-high energy collimators can be used for the assessment of myocardial viability as accurately as FDG PET. However, a slight difference was observed in the defect scores mainly due to attenuation in the inferior wall. Therefore, a slightly different cut-off level for assessing myocardial viability should be applied to the inferior wall when using FDG SPECT.     

Anterior choroidal artery infarction presenting as a progressive cognitive deficit

PURPOSE: The authors describe a patient in whom neuroimaging using Tc-99m HMPAO SPECT, F-18 fluorodeoxyglucose (F-18 FDG) coincidence imaging, and magnetic resonance imaging (MRI) identified an anterior choroidal artery infarction. Neuroimaging played a critical role in confirming this diagnosis, because the patient had symptoms of progressive cognitive decline and satisfied the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for Alzheimer's disease (AD). METHODS: Tc-99m HMPAO brain SPECT was performed using a triple-head gamma camera. F-18 FDG scanning was obtained 40 minutes after intravenous injection of 5 mCi F-18 FDG using a coincidence camera. A brain MRI scan was performed using a 1.5-Tesla scanner. RESULTS: Tc-99m HMPAO SPECT showed focal hypoperfusion to the right parahippocampal cortex. F-18 FDG coincidence imaging showed a more extensive reduction in glucose metabolism compared with SPECT. The MRI scan confirmed the presence of a small segmental choroidal artery infarction. The Tc-99m HMPAO and F-18 FDG scans were not consistent with AD. CONCLUSIONS: This case illustrates the value of the regional cerebral blood flow SPECT for evaluating memory impairment in the elderly. Decreased regional cerebral blood flow to the posterior temporoparietal region is consistent with AD, whereas regional cerebral blood flow diminution in a vascular territory is consistent with vascular dementia. In this case, the patient was clinically diagnosed with AD, and SPECT was performed to establish the baseline regional cerebral blood flow before the cholinesterase inhibitor donepezil was administered. An infarction was diagnosed on the regional cerebral blood flow brain SPECT scan, which was later confirmed by MRI. Infarctions of the parahippocampal cortex may resuft in memory impairment, which can appear clinically similar to AD.     

Imaging with 99mTc ECDG targeted at the multifunctional glucose transport system: feasibility study with rodents

PURPOSE: To evaluate the feasibility of technetium 99m ((99m)Tc) ethylenedicysteine-deoxyglucose (ECDG) imaging in tumor-bearing rodents. MATERIALS AND METHODS: ECDG was synthesized by means of reacting ethylenedicysteine with glucosamine, with carbodiimide as the coupling agent. Hexokinase assays were performed at an ultraviolet wavelength of 340 nm. To determine whether blood glucose level could be altered, ECDG or glucosamine was injected into six rats. In a separate study, ECDG followed by insulin was administered to three rats. To determine biodistribution, lung tumor cells were intramuscularly injected into the hind legs of 18 nude mice. The animals were then injected with (99m)Tc ECDG or fluorine 18 ((18)F) fluorodeoxyglucose (FDG) (0.037-0.074 MBq per mouse). Radioactivity was measured in tissue excised from the animals. Scintigraphy was performed in three groups: in group 1 to demonstrate that different-sized tumors could be imaged after (99m)Tc ECDG administration, in group 2 to ascertain whether tumor uptake of (99m)Tc ECDG was perfusion related, and in group 3 to demonstrate that tumor uptake of (99m)Tc ECDG occurred by means of a glucose-mediated process. RESULTS: ECDG was positive for phosphorylation at hexokinase assay. Blood glucose level increased with ECDG injection and decreased with insulin administration. Tumor-to-brain tissue and tumor-to-muscle tissue ratios of (99m)Tc ECDG uptake were higher than those of (18)F FDG uptake. Scintigraphic results demonstrated the feasibility of (99m)Tc ECDG imaging. CONCLUSION: There are similarities between (99m)Tc ECDG uptake and (18)F FDG uptake in tumors, and study findings supported the potential use of (99m)Tc ECDG as a functional imaging agent.     

Comparison of thallium-201 and F-18 FDG SPECT uptake in squamous cell carcinoma of the head and neck.

PURPOSETo compare the uptake of 2-[F-18] fluoro-2-deoxy-D-glucose (fludeoxyglucose F-18; F-18 FDG) and thallous chloride Tl 201, using single-photon emission CT (SPECT), for the detection and location of squamous cell carcinoma of the head and neck.METHODSFive patients with biopsy-proved squamous cell carcinoma of the upper aerodigestive tract underwent both F-18 FDG and thallium-201 SPECT on the same day. F-18 FDG SPECT was performed using a dual-head gamma camera equipped with commercially available, extremely high-energy collimators (full width half-maximal height, 17 mm for 511 keV photons). Tumor size was estimated at 1.0 to 5.0 cm3 in these cases.RESULTSF-18 FDG SPECT showed five of five primary tumors. In two of the five cases, normal salivary gland activity severely limited thallium SPECT, and the tumors could not be definitively identified. Two of four lymph node groups that were positive for metastatic disease by CT criteria were shown by F-18 FDG SPECT. None were seen with thallium imaging. In one case, F-18 FDG SPECT was able to show a tumor that was not visible on CT.CONCLUSIONSF-18 FDG has advantages over Tl-201 as a squamous cell carcinoma imaging agent (primarily because of its reduced salivary activity). F-18 FDG SPECT has potential as a viable, less expensive alternative to F-18 FDG positron emission tomography. The ultimate value of F-18 FDG SPECT imaging for detecting occult malignancy, monitoring therapeutic effectiveness, or evaluating tumor recurrence remains to be determined in patients with squamous cell carcinoma of the head and neck.     

Phase analysis by gated F-18 FDG PET/CT for left ventricular dyssynchrony assessment: a comparison with gated Tc-99m sestamibi SPECT

Purpose

To investigate the value of gated F-18 FDG PET/CT on left ventricular (LV) dyssynchrony assessment in comparison with gated Tc-99m sestamibi SPECT in patients with coronary artery disease (CAD).

Methods

The data of 100 consecutive CAD patients who underwent both gated myocardial Tc-99m sestamibi SPECT and F-18 FDG PET/CT imaging were analyzed. Phase standard deviation (SD) and histogram bandwidth (BW) were derived from phase analysis using Cedars software package. The correlation and agreement of SD and BW between Tc-99m sestamibi SPECT and F-18 FDG PET/CT were examined. Myocardial viability and the site of latest activation assessed by the two imaging methods were compared as well.

Results

A moderate correlation for SD (r = 0.58, p < 0.0001) and BW (r = 0.60, p < 0.0001) was found between gated SPECT and gated F-18 FDG PET/CT. Bland–Altman analysis revealed an overestimation of SD and BW (6.4° ± 14.3° and 22.0° ± 46.8°) by gated F-18 FDG PET/CT. Multivariate logistic regression analysis identified that significant LV remodeling on SPECT imaging, LV functional parameters and F-18 FDG uptake ratio of myocardium to blood pool (SUV_M/B) were associated with the overestimation. Myocardial SPECT and F-18 FDG PET/CT had a 67.1 % identity in determining the latest activation site and 5.2 % more viable myocardium was detected by F-18 FDG PET/CT than SPECT.

Conclusion

Gated F-18 FDG PET/CT moderately correlated with gated Tc-99m sestamibi SPECT in assessing LV dyssynchrony. Gated F-18 FDG PET/CT phase analysis should be cautiously applied in CAD patients with significant LV remodeling on SPECT imaging, severe LV functional impairment or poor myocardial F-18 FDG uptake.     

The bone scan

Bone imaging continues to be the second greatest-volume nuclear imaging procedure, offering the advantage of total body examination, low cost, and high sensitivity. Its power rests in the physiological uptake and pathophysiologic behavior of 99m technetium (99m-Tc) diphosphonates. The diagnostic utility, sensitivity, specificity, and predictive value of 99m-Tc bone imaging for benign conditions and tumors was established when only planar imaging was available. Currently, nearly all bone scans are performed as a planar study (whole-body, 3-phase, or regional), with the radiologist often adding single-photon emission computed tomography (SPECT) imaging. Here we review many current indications for planar bone imaging, highlighting indications in which the planar data are often diagnostically sufficient, although diagnosis may be enhanced by SPECT. (18)F sodium fluoride positron emission tomography (PET) is also re-emerging as a bone agent, and had been considered interchangeable with 99m-Tc diphosphonates in the past. In addition to SPECT, new imaging modalities, including (18)F fluorodeoxyglucose, PET/CT, CT, magnetic resonance, and SPECT/CT, have been developed and can aid in evaluating benign and malignant bone disease. Because (18)F fluorodeoxyglucose is taken up by tumor cells and Tc diphosphonates are taken up in osteoblastic activity or osteoblastic healing reaction, both modalities are complementary. CT and magnetic resonance may supplement, but do not replace, bone imaging, which often detects pathology before anatomic changes are appreciated. We also stress the importance of dose reduction by reducing the dose of 99m-Tc diphosphonates and avoiding unnecessary CT acquisitions. In addition, we describe an approach to image interpretation that emphasizes communication with referring colleagues and correlation with appropriate history to significantly improve our impact on patient care.     

符合线路SPECT在消化系统肿瘤术后复发转移中的应用研究

探讨18F-FDG符合线路SPECT在消化系统肿瘤术后复发转移中的临床应用价值.材料和方法:对35例临床怀疑复发转移的消化系统肿瘤术后患者行18F-FDG符合线路SPECT显像,对其显像结果进行分析,计算其诊断的准确率、灵敏度、特异性、阳性预测值、阴性预测值及其95%可信区间,并与B超、CT、MRI的诊断结果相比较.结果:在35例消化系统肿瘤术后患者中,其诊断的准确率、灵敏度、特异性、阳性预测值、阴性预测值分别为91.4%、88.9%、100%、100%、72.7%;其95%可信区间分别为77%～98%、71%～98%、63%～100%、86%～100%、39%～94%.符合线路SPECT的诊断准确率、灵敏度明显高于B超,与CT和MRI的比较尚无显著性差异;95%可信区间分析,结果显示符合线路SPECT高于B超、CT和MRI;18F-FDG符合线路SPECT和B超、CT、MRI联合应用在某些病例的诊断中具有互补性.结论:18F-FDG SPECT/PET显像在消化系统肿瘤术后复发转移的诊断中具有较高的临床应用价值.     

18FDG SPECT to assess myocardial viability: initial experience at a hospital remote from a cyclotron

18F-Fluorodeoxyglucose positron emission tomography (18FDG PET) is the recognized gold standard for the assessment of myocardial viability, but is not widely available in the UK. FDG imaging on a gamma camera with high-energy collimators (FDG SPECT) has been shown to have an accuracy comparable with that of FDG PET for the assessment of myocardial viability. This study was performed to assess the feasibility of introducing FDG SPECT for myocardial viability at a hospital a considerable distance away from a cyclotron (200 miles). Twenty-three patients, who were being actively considered for revascularization but had demonstrated fixed defects on stress/rest with nitrate tetrofosmin imaging, underwent FDG SPECT. Image quality was acceptable in all patients. Nine out of the 23 patients with defects classed as fixed on tetrofosmin imaging demonstrated viability on FDG SPECT. Six of these nine patients, reported to have some viable myocardium on FDG SPECT, underwent revascularization as a result. This study has demonstrated that FDG SPECT is feasible at a site some distance from a cyclotron.     

Breast cancer imaging with PET and SPECT agents: an in vivo comparison

Several radiopharmaceuticals and imaging techniques are proposed for breast cancer imaging. Since limited data are available of the uptake of SPECT and PET radiopharmaceuticals in malignant breast tumors and their metastases the aim of this study was to compare the uptake values and to correlate these data with imaging findings. Methods: We have studied the uptake of F-18 FDG, Tc-99m MIBI and Tc-99m (V)DMSA in 31 tumors using immunosuppressed rats implanted with HH-16 clone 4 mammary tumor cells. Tumor gamma camera and PET imaging was performed to gain biokinetic data and uptake values by ROI-analysis. Results: Tumor uptake was highest for F-18 FDG > Tc-99m (V)DMSA > Tc-99m MIBI. The uptake ratios (tumor to muscle) correlated well with the ratios calculated by ROI-analysis determined by imaging. Conclusions: In this in-vivo model, F-18 FDG revealed the best uptake and imaging properties and may be the radiopharmaceutical of choice for routine breast cancer imaging.     

肺部病变18F-FDGSPECT符合线路显像

目的:探讨18F-FDG SPECT符合线路显像对肺部病变的定性诊断价值。材料和方法:用双探头SPECT符合线路对肺部病变患者进行18F-FDG肿瘤代谢显像,分析检查结果并与CT进行比较。结果:48例肺部病变患者18F-FDG显像诊断结果为真阳性37例,真阴性7例,假阳性3例和假阴性1例。其诊断的准确率、灵敏度和特异性分别为91.7％,97.4％和70％。诊断准确率显著高于CT检查。结论:18F-FDG SPECT符合线路显像对肺部病变具有较高的定性诊断价值。     

The role of hybrid cameras in oncology

The rapid advances in imaging technologies are a challenge for nuclear medicine physicians, radiologists, and clinicians who must integrate these technologies for optimal patient care and outcome at minimal cost. Multiple indications for functional imaging using F-18-fluorodeoxyglucose (FDG) are now well accepted in the field of oncology, including differentiation of benign from malignant lesions, staging malignant lesions, detection of malignant recurrence, and monitoring therapy. The use of FDG imaging was first shown using dedicated positron emission tomography (PET) with multiple full rings of bismuth germanate detectors. Most manufacturers now have available hybrid gamma cameras capable of imaging conventional single-photon emitters, as well as positron emitters such as FDG. This new technology was developed to make FDG imaging more widely accessible, first using single photon emission computed tomography (SPECT) with high-energy collimators, and then using dualhead coincidence (DHC) detection with multihead gamma cameras that improved spatial resolution. Most hybrid gamma cameras are now equipped with thicker NaI(TI) crystals to improve sensitivity. Technical developments are still evolving with correction for attenuation and new iterative reconstruction algorithms to improve the quality of the images. Users need to be familiar with the rapid developments of the technology as well as its limitations. Currently, one model of hybrid gamma camera is equipped with an integrated x-ray transmission system for attenuation correction, anatomic mapping, and image fusion. This powerful tool has promising clinical applications including intensity-modulated radiation therapy.     

Dichotomy between Tc-99m MDP bone scan and fluorine-18 fluorodeoxyglucose coincidence detection positron emission tomography in patients with non-Hodgkin's lymphoma

The authors report two cases of non-Hodgkin's lymphoma that were evaluated not only by conventional staging work-up but also additional Tc-99m MDP bone scans and fluorine-18 fluorodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomographic (PET) imaging. There were discordant results between the Tc-99m MDP bone scans and F-18 FDG CoDe PET. In the first case, the bone marrow biopsy was positive, and F-18 FDG CoDe PET was consistent with a malignancy, but the findings of the Tc-99m MDP bone scintiscan were negative. In the second case, the bone marrow biopsy was negative, but F-18 FDG CoDe PET revealed focal skeletal involvement, which improved markedly on the follow-up study after chemotherapy. If skeletal involvement has a focal distribution and is confined to the marrow cavity, both bone marrow biopsy and bone scintigraphy can be falsely negative. In this situation, F-18 FDG PET is useful and revealing.