Showed Perfusion Abnormalities Research Articles

Sildenafil for the Treatment of Patients With COVID-19 and Perfusion Mismatch on Subtraction Computed Tomography Angiography: A Pilot, Placebo-Controlled Randomised Trial

Background: Severe gas exchange impairment can develop even in initial stages of COVID-19 pneumonia. SARS-CoV-2 seems to affect the regulation of pulmonary perfusion, through a renin-angiotensin system imbalance that occurs as a result of the virus binding to ACE2. Hypoperfusion to areas of well-aerated lung parenchyma results in a ventilation-perfusion mismatch that can be characterized using subtraction computed tomography angiography (sCTA). We aimed to investigate the potential efficacy and safety of oral sildenafil in the treatment of inpatients with COVID-19 that showed perfusion abnormalities in sCTA.Methods: This triple-blind, single-centre, placebo-controlled trial, was done at Hospital Naval Almirante Nef, Chile. We enrolled adult patients (>18 years of age) with clinically diagnosed, highly probable or confirmed COVID-19 infection, that were admitted for inpatient treatment, and with a sCTA carried out within 24 hours of admission that showed perfusion abnormalities in areas of well-aerated lung parenchyma. Patients were randomly assigned (1:1) to receive sildenafil (25 mg orally three times a day for seven days) or placebo. The primary endpoint was the change in the ratio between arterial oxygen partial pressure and fractional inspired oxygen (PaO2/FiO2 ratio), and a co-primary endpoint was the change in alveolar-arterial oxygen gradient (A-a gradient), both of which were calculated 1 hour after administration of the intervention on the first day, and on a daily basis during follow-up, using samples from an arterial line in all patients, and analysed using a two-way repeated-measures analysis of variance (ANOVA). Secondary endpoints including intensive care unit admission, the requirement of non-invasive mechanical ventilation or requirement of high-flow nasal cannula, initiation of mechanical ventilation and mortality rates were evaluated using survival analysis with the Kaplan-Meier method and log-rank statistic. The trial is now done. This trial is registered with ClinicalTrials.gov, NCT04489446.Findings: Between August 20, 2020 and March 31, 2021, we recruited 20 patients per group. No statistically significant differences in mean PaO2/FiO2 ratios (repeated measures ANOVA p=0·67) and A-a gradients (repeated measures ANOVA p=0·69) were found between study groups. Invasive mechanical ventilation had to be initiated in four patients, all in the placebo arm, showing a statistically significant difference with the sildenafil arm (logrank p=0·04). Patients allocated to the sildenafil arm also showed a significantly shorter median length of stay in the hospital when compared with the placebo group (9 IQR 7-12 days vs 12 IQR 9-21 days, p=0·04).Interpretation: Sildenafil treatment decreased the need for initiation of invasive mechanical ventilation and reduced the length of stay in the hospital. However, there were no statistically significant differences in the oxygenation parameter (PaO2/FiO2 ratio and A-a gradient). The improvement in clinically relevant outcomes, without significant differences in specific laboratory outcomes, warrants the conduction of larger trials using sildenafil for the treatment of COVID-19 patients with specific perfusion patterns in sCTA.Clinical Trial Registration Details: This trial is registered with ClinicalTrials.gov, NCT04489446.Funding Information: There were no external sources of funding for this investigation.Declaration of Interests: We declare no competing interests.Ethics Approval Statement: The study was approved by the ethics committee of Hospital Naval Almirante Nef, and by the ethics committee of Universidad Andres Bello, Chile. All patients provided written informed consent before randomisation.

Ischemic burden assessment of myocardial perfusion CT, compared with SPECT using semi-quantitative and quantitative approaches

BackgroundWe aimed to compare the myocardial ischemic burden assessed using semi-quantitative and quantitative analysis of computed tomography-myocardial perfusion imaging (CT-MPI) with that of single-photon emission computed tomography (SPECT). MethodsFrom 2011 to 2013, 97 patients who underwent CT-MPI and SPECT were evaluated. The extent and severity of perfusion defects were assessed on a 5-point scale using a standard 16-segment model, and were expressed as summed stress score (SSS) and summed difference score (SDS). Receiver operating characteristic (ROC) curves for quantitative parameters were generated for the diagnosis of abnormal perfusion defect (SSS ≥ 4) and presence of ischemia (SDS ≥ 2) on SPECT. ResultsOn CT-MPI, 298 (19.2%) of the 1552 segments showed perfusion abnormalities during stress, whereas perfusion abnormalities were shown in 179 (11.5%) segments on SPECT-MPI. On a per-person basis, there was good agreement, with intraclass correlation coefficients of 0.78 for SSS and 0.72 for SDS. A significant reduction of attenuation in stress and myocardial perfusion reserve index, along with an increase in % defect volume of CT-MPI, were demonstrated as the degree of perfusion defect or ischemia on SPECT increased. On the ROC curves, % defect volume on CT-MPI demonstrated the highest area under the curve: 0.91 for abnormal perfusion defect and 0.89 (all p < 0.001) for the presence of ischemia on SPECT. ConclusionsSemi-quantitative analysis of CT-MPI showed good accordance with SPECT. A quantitative approach for CT-MPI, especially % defect volume, may provide additional value in the identification of myocardial perfusion abnormalities.Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT01696006.

Coronary-to-pulmonary artery fistula in adults: Evaluation with thallium-201 myocardial perfusion SPECT.

ObjectivesWith the increasing use of multi-detector CT, the number of detected cases with coronary-to-pulmonary artery fistula (CPAF) has increased. Several previous studies reported severe cases of angina, but no appropriate tests to evaluate myocardial perfusion for patients with CPAF have been established. We evaluated the hemodynamic characteristics of CPAF using thallium-201 (Tl-201) single photon emission computed tomography (SPECT).Materials and methodsTl-201 SPECT was performed in 17 patients with CPAF, but without evidence of coronary artery disease on coronary computed tomography angiography (CCTA) (age, 58.5±13.3 years; 8 men). Quantitative analysis of scintigraphic data was performed. Additionally, perfusion abnormalities were compared with CCTA findings. Medical records were obtained to define clinical data, diagnostic findings, symptoms, management, follow-up data, and major adverse cardiac events (MACE).ResultsSix patients (35.2%) showed perfusion abnormalities on SPECT studies and could be classified as follows: 3 patients, no reversible ischemia (3/17, 17.6%); 1 patient, mild ischemia (1/17, 5.8%); and 2 patients, moderate ischemia (2/17, 11.7%). During the follow-up, ten patients (58.8%) improved under medical management and 5 patients (29.4%) underwent surgical ligation for CPAF with symptomatic improvement in 4 patients. Seven patients performed follow-up myocardial perfusion SPECT, and symptomatic improvement correlated well with scintigraphic perfusion improvement in 6 patients No MACE was observed.Clinical significanceTl-201 myocardial perfusion SPECT might be useful for determining the hemodynamic status and for risk stratification in patients with CPAF.

Perfusion CT in acute stroke: effectiveness of automatically-generated colour maps.

To evaluate the accuracy of perfusion CT (pCT) in the definition of the infarcted core and the penumbra, comparing the data obtained from the evaluation of parametric maps [cerebral blood volume (CBV), cerebral blood flow (CBF) and mean transit time (MTT)] with software-generated colour maps. A retrospective analysis was performed to identify patients with suspected acute ischaemic strokes and who had undergone unenhanced CT and pCT carried out within 4.5 h from the onset of the symptoms. A qualitative evaluation of the CBV, CBF and MTT maps was performed, followed by an analysis of the colour maps automatically generated by the software. 26 patients were identified, but a direct CT follow-up was performed only on 19 patients after 24-48 h. In the qualitative analysis, 14 patients showed perfusion abnormalities. Specifically, 29 perfusion deficit areas were detected, of which 15 areas suggested the penumbra and the remaining 14 areas suggested the infarct. As for automatically software-generated maps, 12 patients showed perfusion abnormalities. 25 perfusion deficit areas were identified, 15 areas of which suggested the penumbra and the other 10 areas the infarct. The McNemar's test showed no statistically significant difference between the two methods of evaluation in highlighting infarcted areas proved later at CT follow-up. We demonstrated how pCT provides good diagnostic accuracy in the identification of acute ischaemic lesions. The limits of identification of the lesions mainly lie at the pons level and in the basal ganglia area. Qualitative analysis has proven to be more efficient in identification of perfusion lesions in comparison with software-generated maps. However, software-generated maps have proven to be very useful in the emergency setting. Advances in knowledge: The use of CT perfusion is requested in increasingly more patients in order to optimize the treatment, thanks also to the technological evolution of CT, which now allows a whole-brain study. The need for performing CT perfusion study also in the emergency setting could represent a problem for physicians who are not used to interpreting the parametric maps (CBV, MTT etc.). The software-generated maps could be of value in these settings, helping the less expert physician in the differentiation between different areas.

Gated SPECT in patients with hypertrophic obstructive cardiomyopathy undergoing transcoronary ethanol septal ablation

Background. Transcoronary ethanol septal ablation (TESA) is a novel treatment for obstructive hypertrophic cardiomyopathy (HOCM). Our objective was to evaluate the use of gated single photon emission computed tomography (SPECT) in patients with HOCM and the effects of TESA on myocardial perfusion. Methods and Results. We performed gated SPECT and Doppler echocardiography before and 6 weeks after TESA in 30 patients with severe HOCM. The lung-to-heart and septal-to-lateral wall count-activity ratios were calculated. Before ablation, SPECT showed perfusion abnormalities in only 6 patients. Asymmetric septal hypertrophy was noted in 21 patients (70%). In patients with a lung-to-heart ratio greater than 0.50 before ablation, the ratio decreased from 0.56 ± 0.04 to 0.45 ± 0.08 after ablation ( P < .01). The septal-to-lateral wall ratio also decreased significantly after ablation. Mean Doppler pressure gradient across the left ventricular outflow tract decreased from 52 ± 39 mm Hg to 13 ± 13 mm Hg ( P < .01) immediately after ablation and to 10 ± 21 mm Hg 6 weeks later ( P < .01). There were no significant changes in left ventricular ejection fraction by gated SPECT after the procedure. SPECT studies done after ablation showed fixed septal defects in 29 of 30 patients (96.7%). The defects involved the basal and mid septum in 100% and 38% of patients, respectively, and ranged in size from 2% to 30% of the left ventricle (mean, 8.8% ± 7.0%). Conclusions. TESA is an effective technique for relieving left ventricular outflow obstruction in patients with HOCM. Myocardial gated SPECT can identify the presence and location of infarction after TESA. (J Nucl Cardiol 2002;9:594-600)

Significance of reduced uptake of iodinated fatty acid analogue for the evaluation of patients with acute chest pain

OBJECTIVESTo assess whether 15-(p-[iodine-123] iodophenyl)-3-(R,S) methylpentadecanoic acid (BMIPP) imaging can identify previous ischemic areas, BMIPP SPECT was performed in patients with acute chest pain to compare its findings with those of technetium-99m–tetrofosmin (tetrofosmin) SPECT and coronary angiography.BACKGROUNDBasic studies indicate that BMIPP can identify previous ischemia as reduced tracer uptake.METHODSThis study prospectively enrolled 111 consecutive patients with acute chest pain without myocardial infarction. Tetrofosmin SPECT was performed at rest within 24 h after the last episode of chest pain. Coronary angiography and BMIPP SPECT were also performed on the following day.RESULTSSixty-four of the 87 patients with coronary stenosis or spasm showed BMIPP abnormalities corresponding to the areas of coronary abnormalities (sensitivity 74%), whereas only 33 of them showed perfusion abnormalities (sensitivity 38%) (p < 0.001). Of the 24 patients without coronary stenosis or spasm, 22 showed normal BMIPP SPECT (specificity 92%), and 23 showed normal tetrofosmin SPECT (sensitivity 96%). Coronary stenosis was more often seen in the group with abnormal tetrofosmin/abnormal BMIPP (82%) and with normal tetrofosmin/abnormal BMIPP (69%) than in the group with normal tetrofosmin/normal BMIPP (36%) (p < 0.05). Coronary spasm was observed more often in the group with abnormal tetrofosmin/abnormal BMIPP (83%) and with normal tetrofosmin/abnormal BMIPP (90%) than in the group with normal tetrofosmin/normal BMIPP (27%) (p < 0.05). The extent and severity scores of tetrofosmin and BMIPP in the patients with organic stenosis were significantly higher than those of patients with no organic stenosis or spasm (p < 0.0001).CONCLUSIONSThese data indicate that BMIPP SPECT may specifically identify previous ischemic lesions due to coronary stenosis or spasm in patients with acute chest pain.

Do β-blockers affect the diagnostic sensitivity of dobutamine stress thallium-201 single photon emission computed tomographic imaging?

The effects of beta-blockers on dobutamine stress 201Tl tomographic imaging are not known. This study was undertaken to examine whether beta-blockers affect the sensitivity of dobutamine stress 201Tl imaging. One hundred ten patients without previous myocardial infarction underwent dobutamine stress 201Tl single photon emission computed tomography (SPECT) and coronary arteriography, both studies within a 1-week period. Dobutamine was infused at rates of 5, 10, 20, 30, and 40 microg/kg/min in 3-minute stages. Atropine (as much as 1 mg) was injected intravenously when the patient's heart rate was <100 beats/min. Patients in group 1 (n = 72) were receiving beta-blockers and patients in group 2 (n = 38) were not. The SPECT images in group 1 showed perfusion abnormalities in 62%, 87%, and 94% of patients with one-, two-, and three-vessel coronary artery disease (> or = 50% diameter stenosis), respectively, compared with 75%, 71% and 100% in group 2 (p not significant). The overall sensitivities were 82% (37 of 45) in group 1 and 80% (16 of 20) in group 2 (p not significant). The specificities were 81% (22 of 27) in group 1 and 83% (15 of 18) in group 2 (p not significant). The overall accuracies were the same for both groups (82%). Atropine was added more often in group 1 than in group 2 (37/72 vs 5/38, p < 0.001). Our results suggest that beta-blockers do not affect the sensitivity, specificity, and accuracy of dobutamine stress 201Tl SPECT imaging for detecting coronary artery disease if atropine is given when the chronotropic response is inadequate. In patients receiving beta-blockers, however, the addition of atropine to dobutamine stress is more frequently required.

Brain SPECT in Wilson??s Disease

Brain SPECT in a patient with Wilson's disease revealed deceased pertusion in the areas of the basal ganglia and cerebellum. CT showed no abnormalities. Brain SPECT with Tc-99m HMPAO showed perfusion abnormalities.

Dipyridamole-provoked chest pain implies severe coronary artery disease in children.

The diagnostic significance of dipyridamole-provoked chest pain was studied in 17 children with severe coronary arterial stenotic lesions (CAL) complicated with Kawasaki disease. Although dipyridamole induced chest pain in seven patients (symptomatic group), 10 reported no pain (asymptomatic group). In the asymptomatic group, seven children had one vessel disease (1 VD) of right coronary artery (RCA) and the other three had two vessel disease (2 VD) involving the RCA and left anterior descending artery (LAD). Four multivessel disease patients, one three vessel disease (3VD) and three 2VD of LAD and RCA, and three 1VD of LAD, were symptomatic. In the thallium scans, all patients, except two of the asymptomatic group, showed perfusion abnormalities. In addition, the extent score of the symptomatic group was significantly worse than that of the asymptomatic group (P = 0.01). While only one in six of the asymptomatic group showed abnormal ST depression on treadmill exercise electrocardiography, all patients in the symptomatic group (P = 0.02) showed ischemic ST depression. These findings suggest that the occurrence of chest pain after medication with dipyridamole closely correlates with the severity of CAL in children.

Detection and location of myocardial infarction using technetium-99m sestamibi imaging at rest

Technetium-99m (Tc-99m) sestamibi imaging at rest has been used to detect and localize myocardial infarction. The largest study to date is a cooperative study of 146 patients in 17 institutions. There were 24 normal subjects and 122 patients with documented myocardial infarction based on clinical, enzymatic or electrocardiographic criteria. The presence of segmental myocardial perfusion defects was compared to the presence of a Q wave on the electrocardiogram or wall motion abnormality on gated blood pool scans, performed within 48 hours of the Tc-99m sestamibi study. Of the 122 infarct patients, 118 (97%) showed perfusion abnormalities by Tc-99m sestamibi imaging. A perfusion defect was found in 110 (99%) of 111 patients with a Q wave and a wall motion abnormality, 113 (99%) of 114 patients with a wall motion abnormality and 113 (98%) of 115 patients with a Q wave. Of the 24 normal subjects, 22 (92%) had normal Tc-99m sestamibi images. In 75% of 1,986 segments, both a Tc-99m sestamibi defect and a regional wall motion abnormality on gated blood scans were present. In 11% of segments, wall motion was normal but Tc-99m sestamibi imaging was abnormal; in 14% of segments, wall motion was abnormal and Tc-99m sestamibi images were normal. In the 24 control subjects, 99% of the segments were normal. Thirty-eight patients had coronary angiography. A close relation existed between the coronary anatomy and myocardial Tc-99m sestamibi uptake. All 9 territories supplied by an occluded vessel and poor collaterals had grade 0 uptake (scale 0 to 2: 0 = markedly reduced; 2 = normal). Among totally occluded vessels with good collaterals, 73% had reduced uptake and 27% had normal uptake. In 26 of these patients, the Tc-99m sestamibi uptake was compared to regional wall motion. Overall, wall motion correlated with Tc-99m sestamibi uptake. Abnormal wall motion occurred in 74% of territories with perfusion grade 0, 61% of those with grade 1 uptake and 30% of those scored as grade 2. However, 26% of territories with grade 0 uptake had normal wall motion. Furthermore, of 13 territories with reduced Tc-99m sestamibi uptake, 12 had improved uptake after coronary bypass surgery. These data suggest that resting Tc-99m sestamibi imaging in humans is a reliable means of detecting and localizing myocardial infarction. As a rule, uptake of Tc-99m sestamibi indicates myocardial viability, whereas reduced uptake occurs in nonviable regions. However, some, regions of reduced resting Tc-99m sestamibi uptake may consist of viable but abnormally perfused myocardium.

INITIAL EXPERIENCE WITH SPECT (SINGLE-PHOTON COMPUTERIZED TOMOGRAPHY) OK THE BRAIN USING N-ISOPROPYL 1–123 P-IODOAMPHETAMINE

Forty-six patients were studied with N-isopropyl I-123 p-iodoamphetamine (IMP) and the Harvard Scanning Multidetector Brain System. In nine control patients, good differentiation between the gray and white matter of the cerebral cortex and the basal ganglia was evident. Regional uptake was affected by physiologic maneuvers (visual stimulation). In 24 patients studied for stroke, IMP images demonstrated areas that were involved in acute infarction in eight patients whose initial transmission computerized tomography (TCT) was normal; IMP also showed perfusion abnormalities larger than the TCT abnormality in ten patients. Perfusion abnormalities were present in 23/24 of these patients. Seven patients studied with a history of TIA had normal TCT and IMP images. In three patients studied during seizure activity, regions of hyperperfusion corresponded to the EEG seizure focus. Markedly decreased activity was present in three patients with brain tumor and corresponded to the focal abnormality on the TCT study. Our study demonstrates the feasibility of assessing regional brain perfusion using a radiopharmaceutical that is lipid soluble and has a high extraction fraction in the brain, together with single-photon ECT.

Conditions for "coronary steal" caused by coronary vasodilator in man.

This study was undertaken to assess the conditions necessary to cause the "coronary steal" phenomenon in human subjects. We studied 42 patients (36 males, 6 females, ages 27--70 years) with known or suspected coronary artery diseases using continuous monitoring of the changes in blood pressure and electrocardiogram, thallium-201 myocardial imaging and selective coronary arteriography. Dipyridamole in a dose of 0.4 mg/Kg was given as an intravenous infusion for 4 min and thallium-201 was injected at the 4th minute after completion of the dipyridamole infusion. None of the 20 patients without significant coronary artery disease complained of anginal chest pain or showed ischemic S-T segment depression. Dipyridamole images showed no perfusion abnormalities in 17 of the 20 patients. On the other hand, in 4 of the 22 patients with significant coronary artery disease, anginal chest pain accompanied with S-T segment depression occurred after the dipyridamole infusion. Dipyridamole images showed perfusion abnormalities in 18 of the 22 patients. The 4 patients who experienced an anginal attack had 3 vessel disease on the coronary arteriogram and showed regional perfusion defects on scintigrams corresponding to the regions receiving collaterals. Before the onset of pain, the double product (heart rate X systolic arterial pressure) was unchanged significantly but there was a reduction in the systemic blood pressure. The overall data exhibit the following conditions under which attacks of angina pectoris are induced by dipyridamole: 1) the presence of multiple vessel disease, 2) a fall in systemic blood pressure, and 3) regional malperfusion caused by dipyridamole.

Radioisotope lung scanning in Takayasu's arteritis.

Of 15 patients with Takayasu's arteritis studied by 131I-macroaggregated albumin lung scanning, 12 showed perfusion abnormalities. The lung scan proved very useful in detecting the pulmonary artery disorders associated with Takayasu's arteritis. The pathogenesis of this disease and clinical usefulness of this study are discussed.