SPECT脑血流灌注显像在脑动静脉畸形中的应用

文章回顾了单光子发射计算机体层摄影术(SPECT)脑血流灌注显像技术的发展及其影像特征，并对应用SPECT研究脑动静脉畸形(AVM）与盗血、术后出血的关系、AVM与癫痫的关系以及癫痫灶的定位、功能区AVM的定位、术后复查和随访方法等作了介绍。     

脑动静脉畸形手术后神经功能恶化的临床因素分析

目的 探讨影响脑动静脉畸形(AVM)患者手术后神经功能恶化的临床因素。 方法 对140例脑AVM患者行显微外科切除手术,术前根据Spetzler-MartinAVM分级系统进行分类:Ⅰ级16例(11.4％),Ⅱ级52例(37.2％),Ⅲ级47例(33.6％),Ⅳ级16例(11.4％),Ⅴ级9例(6.4％)。在AVM术后1周和手术半年后随访情况应用Glasgow预后量表(GOS)对患者进行神经功能评价。将各种临床因素与手术后早期、晚期神经功能缺失进行差异显著性检验。 结果术后51例患者(36.4％)出现新的神经功能缺失或术前神经功能缺失症状加重,其中5.7％患者重残(GOS评分≤3),30.7％患者轻残(GOS评分为4或5)。术后随访到118例患者,其中23例(18.6％)仍有神经功能缺失(2.5％重残,16.1％轻残)。神经功能缺失发生率与Spetzlel-Martin分级呈正相关。AVM深静脉引流、Spetzler-Martin分级、AVM的大小与术后早期及晚期神经功能缺失呈显著相关。Logistic回归分析显示,只有Spetzler-Martin分级与术后早期及晚期神经功能缺失显著相关。 结论 Spetzler-Martin分级、AVM深静脉引流和AVM大小是与脑AVM术后神经功能恶化相关的重要临床因素,而最重要的是Spetzler-Martin分级。     

药物诱发单光子发射型计算机断层成像脑血流灌注显像在药物难治性癫痫定位诊断中的临床应用

目的探讨药物诱发单光子发射型计算机断层成像(SPECT)脑血流灌注显像(rCBF)在药物难治性癫痫定位中的作用。方法对入选的77例药物难治性癫痫病人分别行常规脑电图(EEG)、视频脑电图(VEEG)、CT或磁共振成像(MRI)检查及药物诱发SPECT显像,所有77例病人最终全部接受手术治疗,术中行皮层脑电图(ECoG)监测,与EEG、VEEG、CT和MRI、药物诱发SPECT检查结果进行比较分析。结果 EEG、CT、MRI检出癫痫的阳性率分别为37.7%、48.3%和54.2%,与药物诱发SPECT的癫痫检出率90.9%相比差异有统计学意义(P0.05),VEEG的癫痫检出率为83.1%,与药物诱发SPECT相比差异无统计学意义(P0.05)。与术中ECoG比较,药物诱发SPECT对癫痫灶定侧率为90.9%,定位率为71.4%。结论药物诱发SPECT脑血流灌注显像在药物难治性癫痫灶的定位诊断上与ECoG相比较具有较高的一致性。     

成人脑动静脉畸形频度和预后的系统评价

通过系统回顾文献发现,有关成人脑动静脉畸形(AVM)的频度和临床病程的资料很少,其原因在于多数研究的方法存在缺陷,而且通常AVM一经发现就立即治疗.据报道,AVM在未经选择的人群中的频度每年约1/10万,成人时点患病率约为18/10万.1%～2%的卒中、3%的年轻成人卒中和9%的蛛网膜下腔出血是AVM引起的.4%的原发性脑出血由AVM引起的,但对于年轻成人患者,其中1/3的病因是AVM.AVM是原因不明的癫癎首次发作的一个不太常见的病因(占1%),还可引起无神经系统体征的头痛(占0.3%).当AVM被检出时,至少15%的患者无任何症状,约1/5的患者表现为癫癎发作,近2/3的患者主要表现为颅内出血.有限的高质量预后研究表明,AVM患者远期年度粗病死率为1%～1.5%;未破裂AVM首次出血的年度粗危险性低于2%,但出血后第1年内再发出血的危险性高达18%,此后的出血危险性目前还不能确定;未经治疗的AVM发生癫癎的年度危险性为1%.因此,迫切需要在界定良好和稳定的人群中进行关于AVM的频度和临床病程的并考虑到预后异质性的大型前瞻性临床研究.     

多种造影方式在脑脊髓动静脉畸形复合手术中的应用初探

目的探讨复合手术中吲哚氰绿荧光(ICG)造影、DSA和亚甲蓝造影对脑脊髓动静脉畸形(AVM)的应用模式,并对比术中不同造影方法的应用价值。方法回顾性分析首都医科大学宣武医院2013年7月至2015年12月行脑脊髓AVM复合手术55例患者的临床资料,其中脑AVM(Spetzler-Martin≥Ⅲ级)8例,脊髓AVM 47例,平均年龄(33.8±15.6)岁。在复合手术室行术中DSA,并经供血动脉行亚甲蓝造影或ICG造影(初期)。以术后3个月复查DSA评价解剖治愈结果。结果对55例患者均行术中DSA,32例行亚甲蓝造影,4例行术中ICG荧光造影(初期)。术中每例DSA检查(3.6±1.3)次,首次病灶切除后,术中DSA发现有残余病灶者占27.3%(15例)。85.5%(47例)患者获得解剖治愈,其中脑AVM患者(8/8)均获得解剖治愈,脊髓AVM患者83.0%(39例)获得解剖治愈。术后1年随访有3例失访,脑AVM患者改良Rankin评分(mRS)中位数为2.0(0.0~3.8)分,与术前3.5(2.0~4.0)分比较,差异有统计学意义(Z=-2.264,P0.05);脊髓AVM患者术后Aminoff评分为3.5(1.0~6.0)分,与术前4.0(1.0~6.0)分比较,差异无统计学意义(Z=-0.262,P0.05),功能保存者(神经功能评分优于或等于术前)占88.5%(46/52)。结论术中DSA可精确定位畸形团和验证全切,术中亚甲蓝造影可在术野选择性显示供血动脉供应的畸形团,明确血管构筑,ICG造影可显示术区表面的畸形团结构。术中DSA结合亚甲蓝造影可代替ICG造影,达到脑脊髓AVM复合手术解剖治愈的治疗目标。     

颅内动静脉畸形手术前后血管团周围脑皮质局部血流量变化及病理学观察

目的 观察颅内动静脉畸形(AVM)手术切除前、后,血管团周围组织血-脑屏障超微结构及脑皮质局部脑血流量的变化.方法 选择34例AVM行手术切除术的患者,依据Spetzler-Matin分级标准,将AVM分为小型(直径＜3.0 cm)16例、中型(3～6 cm)12例及大型(直径＞6 cm)6例.分别于AVM手术切除前及切除后1、2、3、4和24 h,使用激光多普勒血流仪(LDF)对AVM周围1.5 cm范围内皮质血流量进行监测,并对病灶周围脑组织进行病理学观察.术后7～12 d行头部CT检查,了解脑水肿程度.结果 1例患者术后出现异常脑水肿.①局部脑血流变化畸形团切除后即刻及1、2、3、24 h,中、小型(直径＜6 cm)AVM局部皮质脑血流量较切除前分别增加(53±17)、(77±26)、(38±12)、(29±9)、(8±5)%;切除后4h减少(7±3)%,与切除前比较,切除后即刻及1、2h差异均有统计学意义(P＜0.05);大型AVM(直径≥6 cm)畸形团切除后即刻及1、2、3、4、24 h局部皮质脑血流量较切除前分别增加(130±45)、(112±32)、(100±37)、(116±35)、(147±36)、(120±39)%,与切除前比较,差异均有统计学意义(P＜0.05).②病理学观察电镜观察全部标本,可见病灶周边脑组织的血-脑屏障3层结构有不同程度的变性、破坏,内皮细胞之间紧密连接缝隙增宽,星形胶质细胞足突明显水肿,甚至消失.结论 AVM切除前后脑血流动力学变化是AVM术后诱发异常脑水肿的重要因素;AVM周边脑组织血-脑屏障的结构改变可能是AVM术后发生异常脑水肿的病理生理学基础.     

弥散性动静脉畸形的临床、放射诊断及病理特点

典型的动静脉畸形(AVM)系由异常的动脉和静脉血管团构成,没有毛细血管床,其间的脑实质胶质细胞增生明显、丧失了神经功能。作者分析一组AVM 与其有明显区别,称之为弥散性动静脉畸形。本组12例,年龄9～37岁(平均18.1岁),男女比例相等。主要临床表现:颅内出血8例,癫病发作2例,头痛(无颅内出血)及盗血性脑缺血各1例。脑血管造影证实:AVM 直径2～4cm 3例,4～6cm 4     

脑动静脉畸形治疗方法及适应证的选择

文章分析了影响脑动静脉畸形(AVM)治疗效果的因素,对手术切除、栓塞以及放射外科治疗AVM的特点和适应证的选择进行了详细分析。认为手术、栓塞及放疗三种方法相互结合,是提高AVM治愈率且减少术后病残率和死亡率的最佳方案。     

~(99m)Tc-MIBI SPECT/CT显像联合超声对继发性甲状旁腺功能亢进症患者甲状腺内异位甲状旁腺的术前定位

目的探讨~(99m)Tc-甲氧基异丁基异腈(Tc-99m methoxyisobutylisonitrile,~(99m)Tc-MIBI)单光子发射计算机断层扫描/计算机断层扫描(single-photon emission computed tomography/computed tomography,SPECT/CT)显像联合超声对继发性甲状旁腺功能亢进症(hyperparathyroidism,HPT)术前异位病灶的定位诊断价值。方法回顾2013年9月至2018年12月经东南大学医学院附属江阴医院手术及病理证实的67例继发性HPT患者的影像资料,由多学科团队分析甲状腺内异位甲状旁腺(ectopic intrathyroid parathyroid gland,ETPG)的~(99m)Tc-MIBI SPECT/CT显像及超声表现。结果 67例患者中,3例经术中探查和术后病理证实为ETPG,其中ETPG异位于右侧甲状腺内1枚,异位于左侧甲状腺内2枚。术前~(99m)Tc-MIBI SPECT/CT显像检出2枚;经多学科讨论后由经验丰富的超声医师二次检查后检出1枚; 1枚ETPG并发同侧结节性甲状腺肿~(99m)Tc-MIBI SPECT/CT显像及超声均漏诊,该例还并发甲状腺微小乳头状癌,术前由超声检出。结论联合应用~(99m)TcMIBI SPECT/CT显像及超声对ETPG有较好的术前定位诊断价值,建立长期密切协作的多学科合作模式有助于提高ETPG的定位准确性。     

~(99m)Tc-MIBI SPECT/CT显像联合超声对继发性甲状旁腺功能亢进症患者甲状腺内异位甲状旁腺的术前定位

目的探讨~(99m)Tc-甲氧基异丁基异腈(Tc-99m methoxyisobutylisonitrile,~(99m)Tc-MIBI)单光子发射计算机断层扫描/计算机断层扫描(single-photon emission computed tomography/computed tomography,SPECT/CT)显像联合超声对继发性甲状旁腺功能亢进症(hyperparathyroidism,HPT)术前异位病灶的定位诊断价值。方法回顾2013年9月至2018年12月经东南大学医学院附属江阴医院手术及病理证实的67例继发性HPT患者的影像资料,由多学科团队分析甲状腺内异位甲状旁腺(ectopic intrathyroid parathyroid gland,ETPG)的~(99m)Tc-MIBI SPECT/CT显像及超声表现。结果 67例患者中,3例经术中探查和术后病理证实为ETPG,其中ETPG异位于右侧甲状腺内1枚,异位于左侧甲状腺内2枚。术前~(99m)Tc-MIBI SPECT/CT显像检出2枚;经多学科讨论后由经验丰富的超声医师二次检查后检出1枚; 1枚ETPG并发同侧结节性甲状腺肿~(99m)Tc-MIBI SPECT/CT显像及超声均漏诊,该例还并发甲状腺微小乳头状癌,术前由超声检出。结论联合应用~(99m)TcMIBI SPECT/CT显像及超声对ETPG有较好的术前定位诊断价值,建立长期密切协作的多学科合作模式有助于提高ETPG的定位准确性。     

儿童颅内动静脉畸形手术治疗中DSA的作用

目的探讨儿童颅内动静脉畸形(AVM)手术治疗中DSA的安全性及有效性。方法回顾性分析2015年12月至2017年2月于首都医科大学宣武医院神经外科在复合手术室内治疗的9例2~14岁儿童AVM的临床和影像学资料。其中Spetzler-Martin分级Ⅰ级2例,Ⅱ级3例,Ⅲ级2例,Ⅳ级2例。9例患儿均接受外科手术治疗,并于术中使用DSA技术实时辅助切除AVM。分析患儿外科治疗的影像学治愈率及术中造影的并发症。术后对患儿进行1~15个月临床随访,依据改良Rankin量表(mRS)评分,进行预后评价。结果 9例术中造影提示,完整切除8例,有残余病变1例,随后对残余病变进行了完整切除。畸形团切除后即刻造影证实,9例患儿的畸形团均被完全切除。无一例因术中造影引起并发症。术后1例出现命名性失语,6个月后逐渐恢复;2例出现肺部感染,经抗感染治疗后治愈。术后随访mRS评分0~1分8例,2分1例,无一例再出血。结论儿童AVM手术治疗中行DSA,初步观察安全且有效。术中造影能够实时指导对病变的完全切除,提高AVM的外科治愈率,改善患儿的预后。     

Prognostic value of myocardial perfusion imaging in predicting outcome after renal transplantation

Cardiovascular disease is a significant cause of morbidity and mortality after renal transplantation. Pretransplant screening in a subset of these patients for occult coronary artery disease (CAD) may improve outcome. The objective of this study was to examine the outcome of 600 patients after renal transplantation for end-stage renal disease. Prospective outcome data were collected on 600 consecutive patients who had renal transplantation between 1996 and 1998 at our institution at 42 +/- 12 months after surgery. Stress single-photon emission computed tomographic (SPECT) myocardial perfusion imaging was performed in 174 patients before surgery, 136 (78%) of whom had diabetes mellitus. There were a total of 59 events: 17 cardiac deaths, 14 nonfatal myocardial infarctions, and 28 noncardiac deaths. There were 12 cardiac events and 11 noncardiac deaths among those who had SPECT myocardial perfusion imaging. In a multivariate analysis that included important risk factors, age (p = 0.03 and 0.003, respectively) and diabetes (p = 0.02 and 0.005, respectively) were the predictors of total events and cardiac events in patients who did not undergo stress SPECT perfusion imaging. In the subgroup who had stress perfusion imaging, an abnormal perfusion SPECT study was the only predictor of cardiac events (p = 0.006). The 42-month cardiac event-free survival rate was 97% in patients with normal SPECT images and 85% in patients with abnormal SPECT images (RR 5.04, 95% confidence interval 1.4 to 17.6, p = 0.006). Thus, there is a 2.8% event rate per year after renal transplantation, and approximately 50% of these events are noncardiac. In high-risk patients (most of whom had diabetes) with preoperative stress perfusion imaging, those with normal images had significantly lower cardiac events than those with abnormal images. These results have important implications in patient screening and postoperative management.     

Preoperative comparison of different noninvasive strategies for predicting improvement in left ventricular function after coronary artery bypass grafting

Thallium-201 (Tl-201) imaging and dobutamine stress echocardiography (DSE) are the most frequently used tests in the clinical setting for assessing viability. However, Tl-201 has a suboptimal specificity and DSE a suboptimal sensitivity to predict functional improvement after revascularization. F18-fluorodeoxyglucose (FDG) imaging is considered highly accurate, but availability is limited. Sequential imaging of Tl-201 and DSE may improve accuracy for assessing viability and may be comparable to FDG. Forty-seven patients with ischemic cardiomyopathy underwent Tl-201 single-photon emission computed tomography (SPECT) at rest (4-hour delayed imaging), DSE, and FDG SPECT before bypass surgery. Sensitivity, specificity, and accuracy of 2 sequential strategies were compared with those of FDG SPECT. Strategy 1 considered Tl-201 imaging as the first step, followed by DSE in patients with an intermediate likelihood of viability on Tl-201. Strategy 2 considered DSE as the first step, followed by Tl-201 imaging. Left ventricular ejection fraction was assessed before and 6 months after revascularization, and improvement of >/=5% was considered significant. Tl-201 had a high sensitivity (95%, p <0.05 vs DSE) with a low specificity (57%, p <0.05 vs DSE). DSE had a low sensitivity (63%, p <0.05 vs Tl-201) with a high specificity (89%, p <0.05 vs Tl-201). Both strategies 1 and 2 resulted in high sensitivities (89% and 89%, respectively) and high specificities (89% and 86%, respectively), compared with FDG SPECT (sensitivity 89%, specificity 86%). Sequential testing by Tl-201 SPECT and DSE has a comparable accuracy to FDG SPECT to predict improvement in left ventricular ejection fraction after revascularization. In centers without access to FDG, sequential imaging with Tl-201 and DSE offers an accurate alternative for assessing myocardial viability.     

Recurrence of pulmonary arteriovenous malformations in a female with hereditary hemorrhagic telangiectasia

Pulmonary arteriovenous malformations (AVMs) are an uncommon disorder and may cause life-threatening complications if left untreated. The paucity of good longitudinal data on patients with pulmonary AVMs can be a significant challenge clinically. The authors report a case of recurrence of pulmonary AVMs in a young female with hereditary hemorrhagic telangiectasia (HHT) subjected to transcatheter embolotherapy (TCET) in 1995. Recurrence of pulmonary AVMs was suspected because of marked impairment of oxygenation in 1997 and in 2000, while the patient was pregnant, and later confirmed by imaging studies in early 2003. Despite successful embolization of all visible pulmonary AVMs, contrast echocardiography suggested the presence of intrapulmonary shunt. A shunt of 11.4% was measured using a 100% oxygen test. Loss of flow pattern was the immediate change of pulmonary AVMs after TCET shown by chest sonography. A decrease in the size of the pulmonary AVMs was observed 6 weeks later. This case illustrates the clinical relevance of longitudinal monitoring of arterial blood gases in screening for the recurrence of pulmonary AVMs, particularly in patients with HHT, and the roles of chest sonography and contrast echocardiography in monitoring the efficiency of TCET.     

Technetium‐99m‐sestamibi Redistribution after Exercise Stress Test Identified by a Novel Cardiac Gamma Camera: Two Case Reports

Single photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) employing technetium‐99m (Tc‐99m)‐based imaging tracers is the mainstay of nuclear cardiology for the detection of myocardial ischemia. Current guidelines for same day rest/stress Tc‐99m‐sestamibi SPECT MPI recommend image acquisition 15–60 minutes after the stress testing. A novel sensitive SPECT imaging technique, D‐SPECT, allows fast acquisition of images and captures rapid changes in radiotracer distribution. Here we report 2 cases of SPECT MPI in patients with angiographically confirmed coronary artery disease (CAD) where Tc‐99m‐sestamibi exhibited marked redistribution between early (6–8 min) and late (60–70 min) post‐stress imaging leading to an underestimation of the extent and severity of ischemia on late images. These observations suggest that early imaging maybe more sensitive for CAD detection. Fast SPECT imaging techniques, such as D‐SPECT, will facilitate similar studies in the future as they will allow fast image acquisition at several time points after the stress test. Copyright © 2010 Wiley Periodicals, Inc.     

Prognostic value of thallium-201 single-photon emission computed tomography for patients with multivessel coronary artery disease after revascularization (the Emory Angioplasty versus Surgery Trial [EAST])

The aim of this study was to investigate the relation between reversible thallium single-photon emission computed tomography (SPECT) myocardial perfusion defects at 1-year after revascularization and quantitative indexes in Emory Angioplasty versus Surgery Trial (EAST) and outcomes 3 years after revascularization in 336 patients. EAST was a randomized controlled trial assessing cardiac outcomes for angioplasty versus bypass surgery for patients with multivessel coronary artery disease. During this prospective trial, a substudy included the evaluation of the prognostic value of reversible defects on quantitative thallium SPECT. At 1-year after revascularization, 336 patients underwent SPECT thallium-201 stress myocardial perfusion and 3-hour delayed imaging. Subsequent events, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery, myocardial infarction, and death, were recorded at 3 years. A stress-induced reversible thallium-201 defect was defined using a quantitative index of a reversibility score >30% and severity score >500. Reversible defects were observed more frequently in the percutaneous transluminal coronary angioplasty than in the coronary artery bypass graft surgery treatment groups (46% vs 27%, p <0.001). A total of 123 patients had stress-induced, reversible thallium defects and more events than patients with other perfusion results (freedom from all events was 81.3% vs 94% [p <0.001], and freedom from myocardial infarction and death 88.3% vs 95.5% [p = 0.031]). Quantitative thallium SPECT at 1 year after revascularization risk stratifies patients as to their likelihood of major cardiac outcomes.     

Prognostic value of dobutamine stress technetium-99m-sestamibi single-photon emission computed tomography myocardial perfusion imaging: stratification of a high-risk population.

OBJECTIVES: This work was undertaken to define the intrinsic cardiac risk of the patient population referred for dobutamine stress perfusion imaging and to determine whether dobutamine technetium-99m ((99m)Tc)-sestamibi single-photon emission computed tomography (SPECT) imaging is capable of risk stratification in this population. BACKGROUND: In animal models, dobutamine attenuates the myocardial uptake of (99m)Tc-sestamibi resulting in underestimation of coronary stenoses. Therefore, we hypothesized that the prognostic value of dobutamine stress (99m)Tc-sestamibi SPECT myocardial perfusion imaging might be impaired, owing to reduced detection of coronary stenoses. METHODS: We reviewed the clinical outcome of 308 patients (166 women, 142 men) who underwent dobutamine stress SPECT (99m)Tc-sestamibi imaging at our institution from September 1992 through December 1996. RESULTS: During an average follow-up of 1.9 +/- 1.1 years, there were 33 hard cardiac events (18 myocardial infarctions [MI] and 15 cardiac deaths) corresponding to an annual cardiac event rate of 5.8%/year, which is significantly higher than the event rate for patients referred for exercise SPECT imaging at our institution (2.2%/year). Event rates were higher after an abnormal dobutamine (99m)Tc-sestamibi SPECT study (10.0%/year) than after a normal study (2.3%/year) (p < 0.01), even after adjusting for clinical variables. In the subgroup (n = 29) with dobutamine-induced ST-segment depression and abnormal SPECT imaging, the prognosis was poor, with annual cardiac death and nonfatal MI rates of 7.9% and 13.2%, respectively. CONCLUSIONS: Patients referred for dobutamine perfusion imaging are a high-risk population, and dobutamine stress (99m)Tc-sestamibi SPECT imaging is capable of risk stratification in these patients.     

多模态监测技术在脑动静脉畸形显微外科治疗中的应用效果

目的 探讨神经导航、超声、吲哚氰绿血管造影、神经电生理等多模态监测技术在脑动静脉畸形(AVMs)手术中的应用效果.方法 回顾性连续纳入2019年3月至2021年2月南京大学医学院附属鼓楼医院神经外科行显微外科治疗的AVMs患者51例,其中未破裂AVMs 25例,包括以癫痫发作为首发症状者10例(19.6％);破裂出血A...     

Implementation of technetium-99m MIBI SPECT imaging guidelines: optimizing the two day stress-rest protocol

Objectives. In a previous study in 460 patients, we found that in patients with suspected or known coronary artery disease undergoing stress-rest technetium-99m sestamibi (MIBI) SPECT myocardial perfusion imaging, rest SPECT imaging could be withhold in approximately 20% of patients because of a completely normal stress study. The present study was set up to evaluate the consequences of the implementation of this finding in a subsequent population of patients, and to set standards for the variety of protocols now used for MIBI SPECT imaging. Methods. Within a period of 4 months, 235 consecutive patients referred for MIBI SPECT scintigraphy were studied. All patients had stable cardiac chest pain and underwent symptom-limited exercise MIBI SPECT perfusion imaging. The stress SPECT images were reconstructed and evaluated immediately after acquisition of the images. In case of a clearly normal stress SPECT study, rest imaging was cancelled. Results. Twenty-six of 235 patients (11%) had a completely normal stress MIBI SPECT study and the rest SPECT imaging procedure could be subsequently cancelled. In 20 patients (9%) the stress SPECT was inconclusive, and in 189 (80%) of patients stress imaging was clearly abnormal. In the first month of the study, the nuclear medicine physicians and cardiologists would interprete only 6% of the stress images as normal, while this number increased to 13% after 9 weeks, with a mean of 11% for the whole investigation period of 4 months. Conclusion. In patients undergoing stress MIBI SPECT imaging, it was found justified to cancel rest MIBI SPECT imaging in at least 11% of patients because of a completely normal stress SPECT. As 9% of the images were inconclusive, the number of normal stress images could theoretically increase to 20% if reliable measures are taken to improve reading accuracy. This number is in close agreement with the number of normal stress studies previously reported by our institution and would lead to a considerable reduction of radiation dose, costs, and increased convenience for an important subset of patients.     

Single photon emission computed tomography of the thyroid

Single photon emission computed tomography (SPECT) entails imaging at multiple positions along an arc and computed-assisted reconstruction of transaxial, coronal, and sagittal images. To determine if SPECT imaging of the thyroid augments information provided by planar imaging, both SPECT and pinhole planar scans were performed in 52 patients with thyroid disease. After 123I (n = 45), Tc99m (n = 5), or thallium-201 (n = 2) administration, images were acquired at 30 intervals along a 180 degree arc. Nodules that were hypofunctioning on planar scans (n = 4) were equally well shown on SPECT images. SPECT analysis of 123I uptake by 5 palpable nodules with completely normal 123I planar scans demonstrated the nodular tracer uptake was increased (n = 1), equivalent (n = 3), or decreased (n = 1) in comparison with that of extranodular tissue. In 6 of 12 multinodular goiters, transaxial SPECT images showed tracheal compression, which was confirmed by neck x-ray, flow volume loops, or surgery. A neck phantom study was performed to assess the accuracy of SPECT-determined functional thyroid volume. SPECT-estimated volumes (30-173 mL; n = 11) correlated well with true volumes (r = 0.996; P less than 0.001). Our observations suggest that SPECT is a useful adjunct to planar imaging in 1) estimating functional volume for 131I dosimetry; 2) evaluating the size, extension, and tracheal compression of multinodular goiter; and 3) determining the functional properties of palpable nodules with normal 123I planar pinhole images.