Diagnosis of acute cholecystitis by cholescintigraphy: significance of pericholecystic hepatic uptake

Uptake of radionuclide by the liver next to the gallbladder in cholescintigraphy has been described as a useful secondary sign with a high positive predictive value for the diagnosis of acute cholecystitis. We retrospectively examined 780 consecutive cholescintigrams to (1) determine the positive predictive value at 1 hr of this sign for acute cholecystitis and (2) ascertain if the presence or absence of this finding could differentiate acute from gangrenous cholecystitis. Pericholecystic hepatic activity was present at 1 hr in 48 (34%) of 141 scans in which the gallbladder was not visualized, and cholecystectomy was performed within 6 days of scintigraphy. Forty-five of these patients had acute and three had chronic cholecystitis (94% positive predictive value for acute cholecystitis). In addition, 57% of patients with gangrenous cholecystitis exhibited pericholecystic hepatic activity, and the frequency of this finding was significantly higher (p less than .006) in gangrenous than in acute cholecystitis. In summary, pericholecystic hepatic uptake is a valuable secondary sign in the cholescintigraphic diagnosis of acute cholecystitis. The significance of the finding is (1) a high positive predictive value for acute disease at 1 hr and (2) a statistically significant increased frequency in patients with gangrenous cholecystitis.     

Real-time sonography in suspected acute cholecystitis. Prospective evaluation of primary and secondary signs

Sonographic findings in 497 patients with suspected acute cholecystitis were analyzed prospectively. Combined use of primary and secondary sonographic signs led to excellent positive and negative predictive values. Positive predictive values for stones combined with either a positive sonographic Murphy sign (92.2%) or with gallbladder wall thickening (95.2%) were excellent for acute cholecystitis. Positive predictive value of these signs for patients requiring cholecystectomy was even higher (99.0%). Negative predictive values for combined use of primary and secondary signs to exclude acute cholecystitis were also excellent (95.0% for no stones and negative sonographic Murphy sign). Real-time sonography alone, using both primary and secondary signs, can be definitive in nearly 80% of patients with suspected acute cholecystitis. These patients require no further imaging evaluation. Sonography should be the screening test of choice in acute cholecystitis because it is cost effective, prospectively highly accurate, quick, and better at characterizing and detecting other abdominal lesions than cholescintigraphy. A proposed algorithm is described.     

Prognostic value and pathophysiologic significance of the rim sign in cholescintigraphy

This study reviews 27 patients with nonvisualization of the gallbladder on cholescintigraphy. The preoperative diagnosis of acute cholecystitis was confirmed pathologically in 23. A rim of increased hepatic activity (RIHA) adjacent to the gallbladder fossa was seen throughout the study in 35% with acute cholecystitis and in no patients with chronic cholecystitis. Nine patients with "complicated" cholecystitis (defined pathologically as a late stage of the spectrum of acute cholecystitis) had a positive RIHA in contrast to no patients with "noncomplicated acute cholecystitis" (p less than 0.05). The sensitivity/specificity of the RIHA for "complicated" acute cholecystitis was 45%/100% and the positive/negative predictive value was 100%/39%. Liver tissue that was attached to the gallbladder by adhesions and removed at surgery was reviewed histologically and correlated with the presence or absence of a RIHA. The RIHA seems to be a useful indicator of patients presenting at a later stage of the pathologic spectrum of acute cholecystitis and perhaps at increased risk for complications.     

The rim sign: association with acute cholecystitis

In a retrospective analysis of 218 hepatobiliary studies in patients clinically suspected of acute cholecystitis, a rim of increased hepatic activity adjacent to the gallbladder fossa (the "rim sign") has been evaluated as a scintigraphic predictor of confirmed acute cholecystitis. Of 28 cases with pathologic confirmation of acute cholecystitis in this series, 17 (60%) demonstrated this sign. When associated with nonvisualization of the gallbladder at 1 hr, the positive predictive value of this photon-intense rim for acute cholecystitis was 94%. When the rim sign was absent, the positive predictive value of nonvisualization of the gallbladder at 1 hr for acute cholecystitis was only 36%. As this sign was always seen during the first hour postinjection, it can, when associated with nonvisualization, reduce the time required for completion of an hepatobiliary examination in suspected acute cholecystitis.     

Diagnostic value of the reflux sign in cholescintigraphy after administration of a gallbladder contracting agent--a comparison with X-ray cholangiography

This study reviewed 25 patients with the reflux sign in cholescintigraphy to assess its diagnostic value in evaluating biliary passage. After at least 4-hour fasting 5 mCi of 99mTcPMT or p-butyl IDA was injected intravenously and serial images were recorded before and after intramuscular injection of 10 micrograms of ceruletide diethylamine (caerulein). The reflux sign was determined positive when increased radioactivities in the left hepatic duct (minor reflux; MIR) or more peripheral intrahepatic ducts (major reflux; MAR) were recognized after injection of caerulein. The reflux sign was found in 28 of 237 (12%) studies. Direct and/or indirect X-ray cholangiograms were available in 25 (MIR; 15, MAR; 10). They included common bile duct (CBD) stone in 4, dilated CBD in 4, biliary dyskinesia (BD) in 4, chronic pancreatitis (CP) in 4, gallbladder (GB) stone in 3, duodenal ulcer (DU) in 2, CBD adenoma, pancreatic pseudocyst (PP), duodenal diverticle (DD), and acute cholangitis (AC) in 1 each. Their serum bilirubin levels were within normal limit in all but 2 at the time of cholescintigraphy. Transit time of radionuclides to the duodenum was found prolonged more than 60 min in 17 (68%) patients and persistent pooling in the CBD was found in 8 (28%) patients on scintigrams. The diameter of the CBD on X-ray cholangiogram was ranged 4 to 17 mm. Dilated CBD of more than 10 mm was found in 13 (52%) patients and apparent stenosis of the CBD in 6 (24%) patients. MAR seemed to correspond to increased diameter of the common hepatic more than 2 mm after caerulein injection in DIC. No abnormal findings in X-ray cholangiography was found in 10 (40%) patients including 3 with BD, 2 with GB stone, 2 with DU, 1 each with CP, PP, and AC. All those patients demonstrated MIR. We concluded that major reflux (MAR) sign was helpful in detecting an incomplete obstruction of the CBD, especially in patients with slightly to mildly dilated CBD.     

Preoperative risk stratification by adenosine thallium 201 single-photon emission computed tomography in patients undergoing vascular surgery

Background

Adenosine perfusion scintigraphy is a powerful technique for diagnosing coronary artery disease and risk stratifying patients with recent myocardial infarction.

Methods and Results

We investigated the use of adenosine ²⁰¹Tl tomography to risk stratify 106 patients undergoing vascular arterial reconstruction consisting of lower limb arterial grafting in 44, aortic aneurysmectomy in 36, and carotid endarterectomy in 26 patients. Abnormal tomograms occurred in 57 patients (54%), 47 (82%) of whom had reversible perfusion defects. There were three postoperative deaths, all in the group that underwent aortic aneurysmectomy. Another patient with an aortic aneurysm had unstable angina and one patient who underwent lower limb arterial surgery had pulmonary edema after surgery. No patient without transient defects had an event (negative predictive value 100%). Cardiac events occurred only in patients with transient perfusion defects. However, only 5 of 47 such patients had events (positive predictive value 11%). The perfusion defect size (23%±14% vs 8.9%±135; p=0.034) and the ischemic fraction (20%±16% vs 5.6%±8.9%; p=0.009) were 2.5- and 3.5-fold larger, respectively, in patients with than in those without events. A history of diabetes mellius or previous infarction did not enhance the predictive value of the test.

Conclusion

Thus absence of reversible hypoperfusion during adenosine scintigraphy ensures virtual absence of postoperative cardiac events. Patients undergoing aortic aneurysmectomy may be targeted preferentially for risk-stratification strategies in the future.     

肺灌注/通气显像与肺动脉造影诊断肺栓塞的对比分析

目的：评价肺灌注／通气显像诊断肿栓塞的价值。方法：回顾性分析45例疑肺栓塞患者的肺核素显像结果，并与肺动脉造影检查对照。结果：肺动脉造影诊断为肺栓塞的患者26例，有180个肺动脉支为充盈缺损，其肺灌注显像示167个节段呈完全肺段性或亚肺段缺损，符合率为92．7％。肺动脉造影显示为86个肺动脉支为部分充盈缺损，肺灌注显像有63个肺段或亚肺段缺损，符合率为73．2％（P＜0．01）。肺核素显像对肺栓塞诊断的灵敏度为92．3％，特异性为84．2％，阳性预测值和阴性预测值均为88．9％。26例肺动脉造影诊断为肺栓塞的患者，有23例行肺通气显像，通气／灌注均不匹配。结论：肺灌注／通气显像对肺栓塞诊断具有重要的临床价值。     

Dynamic CT of portal hypertensive gastropathy: significance of transient gastric perfusion defect sign

AIM: To evaluate the "transient gastric perfusion defect" sign as a way of diagnosing portal hypertensive gastropathy (PHG) on multidetector computed tomography (CT). MATERIALS AND METHODS: Ninety-two consecutive patients with cirrhosis underwent three-phase CT and endoscopy. Endoscopy was performed within 3 days of the CT examination. As controls, 92 patients without clinical evidence of chronic liver diseases who underwent CT and endoscopy were enrolled; the findings at endoscopy were used as a reference standard for patients with PHG. Two radiologists who were unaware of the results of the endoscopy retrospectively interpreted the CT images. PHG was diagnosed on dynamic CT if the transient gastric perfusion defect sign was present. The transient gastric perfusion defect was defined as the presence of transient, segmental or subsegmental hypo-attenuating mucosa in the fundus or body of the stomach on hepatic arterial imaging that returned to normal attenuation on portal venous or equilibrium-phase imaging. The frequency of the transient gastric perfusion defect sign was compared between these two groups using Fisher's exact test. The frequency, sensitivity, specificity, positive predictive values, and negative predictive values of the transient gastric perfusion defect sign were also compared between patients with PHG and without PHG in the cirrhosis group. RESULTS: Nine patients of 92 patients with cirrhosis were excluded because of previous procedure or motion artifact; the remaining 83 patients with cirrhosis were evaluated. In the cirrhosis group, 40 (48.1%) of 83 patients showed the transient gastric perfusion defect sign. In the control group, none of the 92 patients showed the transient gastric perfusion defect sign. In the cirrhotic group, the frequency of the transient gastric perfusion defect sign was significantly higher in the patients with PHG (75%, 36/48) than in patients without PHG (11.4%, 4/35). The sensitivity, specificity, positive predictive values, and negative predictive values of the sign for CT diagnosis of PHG in the cirrhosis group were 75, 88.6, 90, and 72.1% respectively. CONCLUSION: The transient gastric perfusion defect sign could be used as a relatively specific sign of PHG in patients with cirrhosis.     

Usefulness of 99Tcm-MDP knee SPET for pre-arthroscopic evaluation of patients with internal derangements of the knee

The aim of this study was to ascertain whether knee SPET can localize lesion sites in patients with internal derangements of the knee. We performed knee SPET as a pre-arthroscopic examination in 63 consecutive patients. SPET imaging was performed with a triple-headed SPET camera 4 h after the injection of 99Tcm-methylene diphosphonate. Arthroscopic diagnoses were as follows: 28 medial meniscus injuries, 24 lateral meniscus injuries, 31 anterior cruciate ligament (ACL) injuries, three posterior cruciate ligament injuries and one medial collateral ligament injury. Of 30 patients with crescent-shaped increased activity at the medial tibial plateau, 22 had medial meniscus injuries (positive predictive value: PPV 73%); of 17 patients with crescent-shaped activity at the lateral tibial plateau, 13 had lateral meniscus injuries (PPV 76%). Of 18 patients with increased activity at ACL attachment sites (primary sign), 17 had ACL injuries (PPV 94%). Of 27 patients with increased activity at bone impaction sites of ACL injury (secondary sign), 22 had ACL injuries (PPV 81%). Of 32 patients who had either a primary or secondary sign, 26 had ACL injuries (PPV 81%). We conclude that knee SPET is very useful in the management of internal derangements of the knee, particularly in determining the need for arthroscopy by localizing lesion sites.     

“Dynamic spot sign” on CT perfusion source images predicts haematoma expansion in acute intracerebral haemorrhage

Objectives

To evaluate the association between dynamic progressive enhancing foci (“dynamic spot sign”) in acute haematoma on CT perfusion source images (CTP-SI) and haematoma expansion.

Methods

One hundred twelve consecutive patients with spontaneous intracerebral haemorrhage according to unenhanced CT, CTP and CT angiography within 6 h of symptom onset were prospectively evaluated. Patients were dichotomised according to the presence/absence of the dynamic spot sign on CTP-SI in haematoma. The predictive value of haematoma expansion was analysed.

Results

Haematoma expansion was detected in 28 patients (25.0 %) on follow-up unenhanced CT images. Thirty patients (26.8 %) demonstrated the dynamic spot sign on CTP-SI, about 83.3 % of patients with haematoma expansion (P?<?0.001). Sensitivity, specificity, positive predictive value, negative predictive value and kappa value for expansion were 89.3 %, 94.0 %, 96.3 %, 83.3 % and 0.814, respectively. In multiple regression, the presence of the CTP dynamic spot sign within acute haematomas independently predicted haematoma expansion; the univariate analysis OR value was 131.667 (29.386–590.289), P?<?0.0001. Moreover, the multivariate analysis CTP dynamic spot sign OR value was 203.996 (32.123–1295.488), P?<?0.0001.

Conclusions

The CTP-SI dynamic spot sign is associated with acute haematoma expansion, is more direct in showing active ongoing bleeding and has a higher predictive value than the CTA spot sign.

Key Points

? It is important to identify potential progression of spontaneous intracerebral haemorrhage. ? Dynamic enhancement within CT perfusion source images is associated with haemorrhage expansion. ? The CTP dynamic spot sign may be present throughout arterial to venous phase imaging. ? The CTP dynamic spot sign carries a higher predive value for haematoma expansion than CTA.     

MRI评价膝关节半月板的桶柄状撕裂

目的 明确5种MRI征象对膝关节半月板桶柄状撕裂的诊断价值。方法 回顾135例患者139个经关节镜证实的膝关节MR图像，其中19个存在半月板桶柄状撕裂。在均不告知关节镜结果的条件下，由2名有经验的放射医生对所有图像进行独立读片，差异协商解决。每个膝关节均记录如下5种MRI征象：双后交叉韧带征(双PCL征)、半月板翻转征、空领结征、碎块内移征和外周残半月板征。分别计算每种征象诊断半月板桶柄状撕裂的敏感度、特异度、阳性预测值、阴性预测值和准确度。结果 5种征象的诊断敏感度分布于52．6％和89．5％之间，特异度分布于83．3％和98．3％之间，阳性预测值分布于42．9％和88．2％之间，阴性预测值分布：于92．7％和98．3％之间，准确度分布于82．7％和96．4％之间。“碎块内移征”和“外周残半月板征”的诊断敏感度最高，“双PCL征”的诊断特异度和阳性预测值最高，而“碎块内移征”具有最高的阴性预测值和诊断准确度。结论 半月板桶柄状撕裂在MRI上可以有多种表现，各种征象对诊断的能力有所不同。     

Non-contrast cardiac computed tomography can accurately detect chronic myocardial infarction: Validation study

Background

This study evaluates whether non-contrast cardiac computed tomography (CCT) can detect chronic myocardial infarction (MI) in patients with irreversible perfusion defects on nuclear myocardial perfusion imaging (MPI).

Methods

One hundred twenty-two symptomatic patients with irreversible perfusion defect (N = 62) or normal MPI (N = 60) underwent coronary artery calcium (CAC) scanning. MI on these non-contrast CCTs was visually detected based on the hypo-attenuation areas (dark) in the myocardium and corresponding Hounsfield units (HU) were measured.

Results

Non-contrast CCT accurately detected MI in 57 patients with irreversible perfusion defect on MPI, yielding a sensitivity of 92%, specificity of 72%, negative predictive value (NPV) of 90%, and a positive predictive value (PPV) of 77%. On a per myocardial region analysis, non-contrast CT showed a sensitivity of 70%, specificity of 85%, NPV of 91%, and a PPV of 57%. The ROC curve showed that the optimal cutoff value of LV myocardium HU to predict MI on non-contrast CCT was 21.7 with a sensitivity of 97.4% and specificity of 99.7%.

Conclusion

Non-contrast CCT has an excellent agreement with MPI in detecting chronic MI. This study highlights a novel clinical utility of non-contrast CCT in addition to assessment of overall burden of atherosclerosis measured by CAC.     

Incremental prognostic value of RNA ejection fraction measurements during pharmacologic stress testing: a comparison with clinical and perfusion variables.

This investigation examined the prognostic power of first-pass radionuclide angiocardiography (RNA) ejection fraction compared with clinical information and myocardial perfusion imaging in patients undergoing pharmacologic stress testing. The value of RNA and myocardial perfusion imaging in predicting death or nonfatal myocardial infarction (MI) is well established. However, limited information exists on the usefulness of combined myocardial perfusion imaging and RNA to predict prognosis, especially in patients undergoing pharmacologic stress testing. METHODS: We identified 240 patients who underwent pharmacologic stress testing with myocardial perfusion imaging and combined RNA. The patients were followed for a mean of 1.4 y. Cox proportional hazards models were used to assess the value in predicting death and MI. Multivariable models were generated to assess the independent incremental predictive value of clinical and nuclear imaging variables. Kaplan-Meier survival and event-free survival estimates were examined in patients with low (< or = 45%) versus high (>45%) ejection fractions. RESULTS: Clinical information, myocardial perfusion imaging, and RNA ejection fraction were significant predictors of the death/MI composite outcome (chi(2) = 7.4, 14.0, and 21.8, respectively). The addition of myocardial perfusion imaging to the clinical information provided incremental prognostic information (chi(2) = 15.2). The addition of RNA ejection fraction provided further predictive information (chi(2) = 22.5). However, when RNA ejection fraction was first added to the clinical information, myocardial perfusion imaging had no incremental prognostic value. CONCLUSION: For hard cardiac events, RNA ejection fraction provides prognostic information besides that provided by clinical and myocardial perfusion imaging. In patients who cannot exercise and are undergoing noninvasive evaluation with pharmacologic stress testing and myocardial perfusion imaging, ejection fraction should be measured simultaneously for risk assessment optimization.     

Fade-out sign on hepatic tissue harmonic compound sonography: a value as a new sign in the diagnosis of fatty liver

Objective

To evaluate the value of the fade-out sign in the diagnosis of fatty liver (FL) on hepatic ultrasound (US).

Methods

We evaluated 127 patients who underwent hepatic US, including 70 patients with FL and 57 normal control subjects. US images were qualitatively evaluated for the presence of the fade-out sign. This sign was considered present if there was a dark band on the deep portion of the liver on the harmonic image when compound sonography (CS) was converted to tissue harmonic CS mode. The degrees of FL were classified into mild, moderate, and severe. The distribution of lengths of dark bands in three groups was examined, and a multiple comparison of the average dark band length was carried out using one-way ANOVA.

Results

The fade-out sign was seen in 55 of 70 FL patients (78.6%) compared to 3 of 57 control subjects (5.3%) (p < 0.001). The sensitivity, specificity, accuracy, and positive predictive value of the fade-out sign for the US diagnosis of FL were 78%, 94%, 85.8%, and 94.8%, respectively. Among the 70 FL, there were 28 mild FL (mean length of dark band; 8.3 mm ± 8.2), 31 moderate FL (mean; 28 mm ± 6.3), and 11 severe FL (mean; 51 mm ± 8.3). There were significant differences in band length according to severity (p < 0.01).

Conclusion

The fade-out sign on hepatic harmonic US was frequently present in FL. As fat infiltration increased, the fade-out sign lengthened. The fade-out sign offers a specific and new sign of FL.     

Results of myocardial scintigraphy with 99mTc-tetrofosmin and dipyridamole administration in patients diagnosed of microvascular angina

The objective of the study was to evaluate the results of the myocardial scintigraphy with 99mTc-tetrofosmin (Tc-Tf) and pharmacological stimulation with dipyridamole in patients diagnosed of microvascular angina. The study population is made up of 50 patients discharged with the diagnosis of microvascular angina who had undergone Tc-Tf-dipyridamole. Clinical and electrical positivity appeared in 40% and 12% of the patients, respectively. Myocardial perfusion defects were found in 35 patients (70%), and were reversible in 21 (60%), fixed in 11 (21%), and combined in 3 (9%). Abnormalities were inferior, anteroseptal and lateral in 21, 18, and 2 patients, respectively. Patients with a positive exercise treadmill test, compared with those with a negative one, had more frequent perfusion abnormalities (91% vs 50%, p = 0.0327) and myocardial ischemia (64% vs 20%, p = 0.392). Women, in comparison with men, had angina (56% vs 22%, p = 0.013), and anteroseptal perfusion abnormalities (26% vs 4%, p = 0.028) more frequently. On the contrary, men had inferior perfusion abnormalities more frequently (57% vs 30%, p = 0.057). Thus, Tc-Tf-dipyridamole shows perfusion abnormalities in 70% of patients with microvascular angina (91% in patients with a positive exercise treadmill test). Scintigraphic pattern may be partially conditioned by gender in these patients.     

双能量CT肺灌注及血管成像与核素肺通气灌注成像诊断肺栓塞的对照研究

目的 通过与核素肺通气灌注显像比较,评价双能量CT肺血管成像(DE-CTPA)及双能量CT肺灌注成像(DE-CTLP)技术诊断肺栓塞的能力.方法 比较50例临床怀疑肺栓塞的患者DE-CTPA、DE-CTLP及核素肺通气灌注显像结果,以非线性相关检验比较DE-CTPA显示肺血管腔内充盈缺损与DE-CTLP显示灌注缺损之间的相关性,以核素为参考标准,应用一致性检验方法(Kappa检验)对照分析两者之间的一致性及DE-CTLP诊断肺栓塞的敏感性和特异性.结果 (1)50例临床怀疑肺栓塞患者中,4例CT图像质量差,不能评价.余46例共920个有效肺段中,DE-CTPA显示262个肺段肺血管腔内充盈缺损,DE-CTLP显示266个肺段明确灌注缺损.核素肺通气灌注扫描显示268个肺段灌注与通气不匹配.(2)DE-CTLP与DE-CTPA两者间显著相关(r=0.883,P<0.01);DE-CTLP与核素肺通气灌注显像的一致性良好(Kappa=0.940,P<0.01);以核素肺通气灌注成像为诊断参考标准,应用DE-CTLP诊断肺栓塞的阳性预测值95.5%(279/292),阴性预测值98.3%(641/652),敏感性96.2%(279/290),特异性98.0%(641/654).(3)应用CareDose 4D技术,DE-CTPA和DE-CTLP患者平均射线损伤剂量为(4.37±0.47)mSv.结论 应用DE-CTPA和DE-CTLP技术可以在一次扫描中同时获得常规CT肺血管成像的血管形态学信息和肺实质血流灌注情况,为临床诊断肺栓塞提供直观、有效的综合影像信息.     

CT血管造影在诊断功能相关性冠状动脉狭窄中的应用

目的以 SPECT 心肌灌注显像(MPI)为参考,评价 CT 血管造影检测功能相关性冠状动脉狭窄(FRCS)的诊断效能.资料与方法2005-11~2011-03在天津医科大学心血管病临床学院同期(30d 内)行冠状动脉 CT血管造影(CCTA)和 MPI 的504例可疑或确诊冠状动脉疾病患者,以 CCTA冠状动脉狭窄≥50%并伴有相应血管支配区域 MPI 灌注缺损作为诊断 FRCS的参考标准.以病例或血管为观察对象,分别计算 CCTA 冠状动脉狭窄≥50%或≥75%时检测 FRCS 的诊断效能.结果以病例为观察对象,CCTA 冠状动脉狭窄≥50%或≥75%检测 FRCS 的灵敏度、特异性、阳性预测值和阴性,预测值分别为67.2%和35.8%、84.7%和97.3%、40.2%和66.7%、94.4%和90.8%,差异均有统计学意义(P<0.05);以血管为观察对象,CCTA 冠状动脉狭窄≥50%或≥75%检测 FRCS 的灵敏度、特异性、阳性预测值和阴性预测值分别为70.2%和33.7%、95.4%和99.0%、42.9%和60.0%、98.5%和97.0%,差异均有统计学意义(P<0.05).结论 CCTA 具有较佳的排除 FRCS 的能力.当冠脉狭窄≥50%时,CCTA 虽然对 FRCS 检测灵敏度较高,但其阳性预测值相对较差.当冠脉狭窄≥75%时,CCTA 检测 FRCS 的阳性预测值有一定的提高.     

Sixty-four slice spiral CT angiography does not predict the functional relevance of coronary artery stenoses in patients with stable angina

Purpose The aim of this study was to evaluate spiral multidetector computed tomography (MDCT) angiography using 64-slice technique in the detection of functionally relevant coronary artery stenoses (CAS). Methods Thirty-eight patients (62±11 years, 28 men) with stable angina (26 with suspected and 12 with known coronary artery disease) were investigated using 64-slice MDCT angiography and gated myocardial perfusion SPECT (gated SPECT); a subgroup of 30 patients had additional invasive coronary angiography (ICA). Stenoses with luminal narrowing of ≥50% were defined as “significant” in MDCT angiography and ICA. MDCT angiography was compared with gated SPECT and the combination of gated SPECT plus ICA with respect to the detection of functionally relevant CAS. Results The sensitivity, specificity and negative and positive predictive values of MDCT angiography in detecting reversible perfusion defects on gated SPECT were 63%, 80%, 94% and 32%, respectively, in vessel-based analysis and 71%, 62%, 72% and 60%, respectively, in patient-based analysis. If only reversible perfusion defects on gated SPECT with CAS ≥50% on ICA were considered, the sensitivity, specificity and negative and positive predictive values were, respectively, 85%, 79%, 98% and 33% for vessel-based analysis and 85%, 59%, 83% and 61% for patient-based analysis. Conclusion Sixty-four slice MDCT angiography failed to predict the functional relevance of CAS, but had a high negative predictive value in the exclusion of functionally relevant CAS in symptomatic patients. An editorial commentary on this paper is available at .     

Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

Purpose

Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain.

Methods and materials

Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT.

Results

In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments.

Conclusion

Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.     

Cholecystokinin cholescintigraphy: victim of its own success?

Numerous publications have reported that a low gallbladder ejection fraction (GBEF) determined by cholecystokinin (CCK) cholescintigraphy has a high positive predictive value for the diagnosis of chronic acalculous cholecystitis (CAC). Clinicians and surgeons have found this test to be clinically useful as an objective method to confirm their clinical diagnosis. However, an abnormally low GBEF is not specific for CAC. For example, numerous other diseases have been associated with a low GBEF, and various therapeutic drugs can cause poor gallbladder contraction. Importantly, improper CCK infusion methodology can result in an erroneously low GBEF. More than one third of healthy subjects and patients who receive sincalide, 0.02 microg/kg infused over 1-3 min, will have an erroneously low GBEF but will have a normal GBEF with a slower infusion (30-60 min) of the same total dose. Because of enthusiastic acceptance of CCK cholescintigraphy by clinicians, the types of patients referred for this test have changed over time. Patients investigated in publications confirming the usefulness of CCK cholescintigraphy had a high pretest likelihood of disease. They underwent extensive workup to rule out other diseases and were followed up for months or years before CCK cholescintigraphy was performed, allowing other diseases to become manifest or symptoms to resolve. However, CCK cholescintigraphy is now being used by clinicians to shorten the workup and follow-up time based on the rationale that CCK cholescintigraphy can quickly confirm or exclude the diagnosis. This new group of referral patients has a lower likelihood of the disease. Many will ultimately be diagnosed with diseases other than CAC. The positive predictive value of this test will likely be lower and the false-positive rate will likely be higher. Nuclear medicine physicians must work to minimize false-positive studies to maintain the confidence of referring clinicians. First, we can educate referring physicians as to the proper use of this study. Next, we must perform CCK cholescintigraphy using optimal methodology that will result in the lowest possible false-positive rate. And finally, we must interpret CCK cholescintigraphy in light of the patient's history, prior workup and clinical setting.