Raymond Lambert

Single Photon Emission Computed Tomography (SPECT) in Cerebellar Disease: Cerebello-Cerebral Diaschisis

Single photon emission computed tomography assessments were conducted in normal controls (n = 25), patients with unilateral cerebellar infarctions (n = 4), patients with olivopontocerebellar atrophy (OPCA; n = 15) and patients with Friedreichs ataxia (FA; n = 6). In subjects with unilateral cerebellar infarctions, crossed cerebellar-cortical diaschisis was observed: reduced cerebellar hexamethylpropyleneamine oxime (HMPAO) uptake was invariably accompanied by a diminution of HMPAO in the contralateral basal ganglia and frontoparietal cortex. OPCA and FA patients had various degrees of decreased HMPAO uptake in both the cerebellum and cerebral hemispheres.

Clinical comparison between thallium-201 and Tc-99m-methoxy isobutyl isonitrile (hexamibi) myocardial perfusion imaging for detection of coronary artery disease.

Abstract99mTc-hexamibi (methoxy isobutyl isonitrile) is a new 99mTc-hexakis analog that can be used as a myocardial perfusion imaging agent. The purposes of this study were to compare 99mTc-hexamibi to 201Tl-thallous chloride myocardial stress scintigraphy in patients referred for investigation of chest pain and to evaluate the sensitivity of 99mTc-hexamibi in detection of coronary artery disease. One hundred patients were prospectively studied with both 201Tl and 99mTc-hexamibi planar imaging. Sixty five patients had a current coronary angiography. There was a total of 97 significantly (≤70%) stenosed major coronary arteries. 99mTc-hexamibi (25 mCi) study was done within a week of the 201Tl scan with similar double products upon standard treadmil stress testing. Rest studies with 99mTc-hexamibi were obtained 24–48 h after the stress test using the same acquisition parameters and dose. Analysis was performed blind by three observers. The left ventricle was divided into five segments in each image. Analysis of 201Tl and 99mTc-hexamibi results in 1500 left ventricle segments showed an overall agreement in 1326/1500 (88.4%) segments. Correlation between the patient diagnosis on the 201Tl and 99mTc-hexamibi studies showed an agreement in 89 patients (89%). 201Tl revealed myocardial uptake defects in 526 segments, detecting 72 out of 97 (74.2%) significantly stenosed coronary arteries and 99mTc-hexamibi detected 513 segments corresponding to 68 (70.1%) stenosed arteries (no significant statistical difference). In conclusion, these results show a good correlation between 201Tl and 99mTc-hexamibi myocardial imaging in the detection of significant coronary artery disease.

Comparison between dipyridamole and adenosine as pharmacologic coronary vasodilators in detection of coronary artery disease with thallium 201 imaging

BackgroundBoth dipyridamole and adenosine are widely used as pharmacologic stressors with 201Tl imaging for detection of coronary artery disease. The purpose of this study was to compare dipyridamole and adenosine 201Tl imaging directly in patients with angiographically proved coronary artery disease.Methods and ResultsFifty-four patients were submitted to two planar 201Tl studies: one with dipyridamole and the other with adenosine. The interval between the two studies varied from 2 to 7 days and the order was assigned randomly. Three standard planar views were obtained 10 minutes and 4 hours after the injection of 3.0 mCi 201Tl. Administration of dipyridamole was as follows: 0.142 mg/kg/min during 4 minutes, followed by a slight exercise and 201Tl injection. The infusion of adenosine was as follows: 0.140 mg/kg/min during 6 minutes with injection of 201Tl after the third minute of infusion. Patients were asked to give their preference considering the number type, severity, and duration of side effects on a scale from 0 (worst) to 5 (best). Reading was done by two experienced observers. The heart was divided into three segments per view. The change in systolic blood pressure was-12±11 mm Hg for adenosine and-5±10 mm Hg for dipyridamole (p<0.001), and the change in heart rate was 18±10 beats/min for adenosine and 8±7 beats/min for dipyridamole (p<0.001). With regions of interest, ischemic/normal wall ratios were determined: 0.78 ± 0.06 for adenosine and 0.83±0.08 for dipyridamole (p<0.001). Adenosine detected 295 normal, 170 ischemic, and 21 scar segments, whereas dipyridamole detected 326, 135, and 25 segments, respectively. Patients preferred adenosine (4.3±1.0 for adenosine vs 3.8±1.5 for dipyridamole; p<0.04) mainly because of the short duration of side effects.ConclusionThis study shows that the use of adenosine with 201Tl imaging may have some advantages over dipyridamole.

Technetium 99m SESTAMIBI myocardial perfusion imaging: comparison between treadmill, dipyridamole and trans-oesophageal atrial pacing “stress” tests in normal subjects

The purpose of this study was to determine the blood clearance, myocardial uptake and heart/lung and heart/liver ratios of technetium 99m methoxyisobutylisonitrile (99mTc-SESTAMIBI) following 3 different types of cardiac stimulation in normal subjects: treadmill stress (STRESS), intravenous administration of dipyridamole (DIP) and trans-oesophageal atrial pacing (TAP). Ten normal volunteers were submitted to 3 injections of 99mTc-SESTAMIBI (10 mCi/70 kg, separated by an interval of 7 days) following STRESS (standard Bruce protocol), DIP (0.142 mg/kg·min during 4 min) and TAP procedures. Blood samples were collected from 1 to 60 min after each 99mTc-SESTAMIBI injection. Planar imaging was performed at 5, 30 and 60 min. Blood retention (percentage of injected dose at 1 min) was 56% ± 4%, 24% ± 4% and 38% ± 6% for STRESS, DIP and TAP, respectively (P<0.001). Myocardial uptake was similar for the 3 procedures while the heart/lung ratio at 60 min was 3.1 ± 0.5, 3.8 ± 0.6 and 3.2 ± 0.5 for STRESS, DIP and TAP, respectively. Heart/liver ratio at 60 min was 1.9±0.5, 1.3±0.3 and 1.1±0.2 for STRESS, DIP and TAP, respectively (P<0.001). These results demonstrated that the 3 types of cardiac stimulation show good imaging parameters with 99mTc-SESTAMIBI.

A high prevalence of dual thyroid ectopy in congenital hypothyroidism: evidence for insufficient signaling gradients during embryonic thyroid migration or for the polyclonal nature of the thyroid gland?

BACKGROUND Thyroid ectopy results from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Most ectopic thyroids are revealed by congenital hypothyroidism and present as a single round mass at the base of the tongue, with no other thyroid tissue. However, some cases have dual ectopy, with part of the tissue having partially migrated. We hypothesized that this occurs more frequently than previously reported. METHODS To determine the prevalence of dual ectopy, we reviewed the pertechnetate scintigraphies of 81 patients with congenital hypothyroidism from thyroid ectopy diagnosed between 2002 and 2011 at our institution. RESULTS We report a series of seven cases (9%) of dual ectopy, representing an incidence ranging from 1:50,000 to 1:70,000. CONCLUSIONS Almost one in 10 cases with congenital hypothyroidism due to thyroid ectopy has dual ectopy. This suggests that two populations of cells diverged at an early stage of development, which may arise from insufficient signaling gradients in surrounding tissues during early organogenesis or may indirectly support the polyclonal nature of the thyroid.

Segmental myocardial contractility versus perfusion in Kawasaki disease with coronary arterial aneurysm

The impact of Kawasaki-related coronary injury on the myocardium was evaluated in 13 patients with persistent coronary aneurysm after a follow-up period of 7.92+/-3.97 years (range 1.8 to 14.3). Myocardial segmental perfusion and contractility integrity were assessed by resting and exercise echocardiography and technetium-99 (Tc-99m) sestamibi scan. Eight patients (61.5%) had giant aneurysms (> or = 8 mm) and 9 had multivessel involvement; the mean diameter of the largest aneurysm was 8.6+/-2.5 mm (range 5 to 14). During the acute phase, myocardial infarction occurred in 1 patient and coronary thrombosis in another. At the latest echocardiographic evaluation, the mean aneurysm diameter was 6.8+/-2.4 mm (range 4.5 to 12), there was persistent giant aneurysms in 5 of 8 patients, and 3 of 9 patients had multivessel involvement. Coronary angiography demonstrated stenosis in 7 of 10 patients, with multiple levels in 2. At sestamibi scan, all 13 patients had perfusion anomalies at rest, whereas only 7 had detectable hypokinesia on echocardiography. With exercise, perfusion returned to near normal in 3 patients, improved in 3, remained unchanged in 4, and worsened in 3 patients. Segmental contractility similarly deteriorated in the latter 3 patients but also in 2 patients whose perfusion scan had improved with exercise. Three patients, normal at rest, developed segmental hypokinesia during exercise. When present, the location of observed changes in contractility on stress echocardiography corresponded to that of perfusion defect. In conclusion, abnormal myocardial perfusion is present long term after complicated Kawasaki disease, the worst anomalies accompanying persistent giant aneurysms. Unfavorable perfusion response was coupled with abnormal contractility; however, enhanced perfusion with exercise correlated poorly with segmental contractility response.

Myocardial technetium 99m-labeled sestamibi single-photon emission computed tomographic imaging in the detection of coronary artery disease: Comparison between early (15 minutes) and delayed (60 minutes) imaging

BackgroundPrevious studies have demonstrated that there is a “partial” myocardial redistribution of99mTc-labeled sestamibi (MIBI) between 1 and 3 hours after intravenous injection at stress. The purpose of this prospective study was to compare MIBI single-photon emission computed tomographic (SPECT) imaging performed 15 and 60 minutes after the injection at stress in the detection of coronary artery disease.Methods and resultsThirty-five patients with coronary artery disease (26 underwent coronary angiography and 23 had a positive201Tl study result) were included in this study. SPECT imaging started 15 minutes after the injection of 25 to 30 mCi MIBI at peak stress (180-degree arc, 32 angles, 25 sec/view, and high-resolution collimator). Patients underwent reimaging at 60 minutes according to the same protocol and with the same gamma camera. A rest study was obtained 75 minutes after the injection of MIBI (25 to 30 mCi) at rest, 48 hours later. Images (divided for a total of 19 segments per patient) were interpreted by two blinded observers for patient diagnosis and segmental comparison. The patient diagnosis was the same for the two protocols: normal = 3, ischemia = 27, and scar = 5. The segmental agreement (k = 0.90) was 632/665 (95.0%). The imaging performed at 15 minutes detected normal, ischemia, and scar in 413, 189, and 63 segments, respectively, whereas the imaging performed at 60 minutes detected 422, 180, and 63 segments, respectively (difference not significant). The early and delayed images were placed side by side for subjective comparison of the extent of the defect. Early imaging showed slightly larger defects in six patients, equal defects in 24 patients, and slightly smaller defects in five patients. Ischemic/normal wall ratios were 0.67 ±0.16 at 15 minutes and 0.68 ±0.15 at 60 minutes.ConclusionsThere is no clinically significant difference between SPECT imaging performed at 15 minutes or 60 minutes after the injection of MIBI at stress. Furthermore, this study showed that it is feasible to obtain good-quality MIBI images even 15 minutes after the injection at stress.

Thyroid scintigraphy in children and adolescents with Hashimoto disease

Between 1989 and 1994, 58 children and adolescents with Hashimoto thyroiditis seen at the Sainte-Justine Hospital had thyroid scintigraphy. Their medical records and films were reviewed retrospectively. Eighty-nine percent of the patients had a homogeneous distribution of tracer on thyroid scintigraphy, unlike the heterogeneous distribution classically reported in adults. In children and adolescents, thyroid scintigraphy is not helpful in the diagnosis of typical Hashimoto thyroiditis.

Comparison between technetium-99m-teboroxime and thallium-201 dipyridamole planar myocardial perfusion imaging in detection of coronary artery disease

Technetium-99m (TC-99m)-teboroxime is a new myocardial perfusion imaging agent. The purpose of this prospective study was to compare Tc-99m-teboroxime with thallium-201 imaging after the administration of dipyridamole. Thirty patients referred for the evaluation of chest pain were studied with both thallium-201 and Tc-99m-teboroxime dipyridamole scans (mean interval 2 days). Dipyridamole was administered at 0.142 mg/kg/min for 4 minutes. Planar imaging (3 standard views) was obtained at 5 and 240 minutes after the injection of 2.2 mCi of thallium-201. Tc-99m-teboroxime (18 to 25 mCi) was injected after dipyridamole infusion. A second injection, at rest, was repeated 4 hours later. Planar imaging (3 standard views of 1 minute/view for the first 2 views, and 90 seconds for the last view) was obtained 2 minutes after Tc-99m-teboroxime injection. Blinded reading was performed by 3 observers. Thallium-201 showed perfusion defects in 182 myocardial segments corresponding to 33 of 45 (73%) significantly stenosed coronary arteries (greater than or equal to 70% reduction in endoluminal diameter), and Tc-99m-teboroxime detected 160 abnormal segments corresponding to 29 of 45 (64%) stenosed arteries. Thallium-201 and Tc-99m-teboroxime studies were normal in 3 patients. In conclusion, this study shows that there is a good correlation in the imaging results found with thallium-201 and Tc-99m-teboroxime using dipyridamole infusion on both a segmental and a diagnostic comparison.

Technetium-99m antimyosin antibody (3–48) myocardial imaging: human biodistribution, safety and clinical results in detection of acute myocardial infarction

Technetium-99m antimyosin (99mTc-AM) antibody imaging may have significant advantages over indium-111 antimyosin in clinical practice. The purpose of this study was to determine the human biodistribution, the safety profile and the sensitivity of99mTc-AM (3–48) imaging in the detection of both Q-wave and non-Q-wave myocardial infarction (MI). Biodistribution and safety parameters were mainly determined in 12 normal healthy volunteers while 40 patients with proven MI (22 Q-wave, 18 non-Q-wave) were injected with99mTc-AM (20–25 mCi) between 5 h and 7 days after the onset of acute chest pain. Three standard planar views were performed at 6 h and at 24 h post injection. Both sets of images were completed in 33 patients while two patients were imaged only at 6 h, three patients only at 18 h and one at 18 and 24 h. One patient was not imaged. Vital signs and ECG were recorded and blood samples for haematology, biochemistry and human antimurine antibodies (HAMA) and urinalysis were obtained in all volunteers and patients. No serious adverse reactions or side-effects attributable to99mTc-AM have been reported. No volunteers or patients developed allergic reactions or significant increases in HAMA titres. Reading of99mTc-AM imaging was performed by two blinded experienced observers. The sensitivity of99mTc-AM in the detection of MI was 100% (21/21) for Q-wave and 83.3% (15/18) for non-Q-wave infarctions. The overall sensitivity was 92.3% (36/39). The three false-negative cases were inferoposterior MI. A certain degree of uptake focalization was seen in 26 out of 35 (74.2%) at 6 h. At 24 h, two patients (5.8%) did not show99mTc-AM uptake while 22 (64.7%) showed intense focal uptake, seven (20.6%) moderate uptake and 3 (8.9%) slight uptake. It is concluded that99mTc-AM (3–48) imaging is safe and shows high sensitivity in the detection of both Q-wave and non-Q-wave MI even with early imaging (6 h post injection). These promising results warrant further clinical investigation.