Henrik Gutte

Detection of Pulmonary Embolism with Combined Ventilation–Perfusion SPECT and Low-Dose CT: Head-to-Head Comparison with Multidetector CT Angiography

The diagnosis of pulmonary embolism (PE) is usually established by a combination of clinical assessment, D-dimer testing, and imaging with either pulmonary ventilation–perfusion (V/Q) scintigraphy or pulmonary multidetector CT (MDCT) angiography. Both V/Q SPECT and MDCT angiography seem to have high diagnostic accuracy. However, only limited data directly comparing these 2 modalities are available. Hybrid γ-camera/MDCT systems have been introduced and allow simultaneous 3-dimensional lung V/Q SPECT and MDCT angiography, suitable for diagnosing PE. The aim of our study was to compare, in a prospective design, the diagnostic ability of V/Q SPECT, V/Q SPECT combined with low-dose CT, and pulmonary MDCT angiography obtained simultaneously using a combined SPECT/MDCT scanner in patients suspected of having PE. Methods: Consecutive patients from June 2006 to February 2008 suspected of having acute PE were referred to the Department of Nuclear Medicine at Rigshospitalet or Frederiksberg Hospital, Denmark, for V/Q SPECT as a first-line imaging procedure. The number of eligible patients was 196. Patients with positive D-dimer results (>0.5 mmol/mL) or a clinical assessment with a Wells score greater than 2 were included and underwent V/Q SPECT, low-dose CT, and pulmonary MDCT angiography in a single session. Patient follow-up was 6 mo. Results: A total of 81 simultaneous studies were available for analysis, of which 38% were from patients with PE. V/Q SPECT had a sensitivity of 97% and a specificity of 88%. When low-dose CT was added, the sensitivity was still 97% and the specificity increased to 100%. Perfusion SPECT with low-dose CT had a sensitivity of 93% and a specificity of 51%. MDCT angiography alone had a sensitivity of 68% and a specificity of 100%. Conclusion: We conclude that V/Q SPECT in combination with low-dose CT without contrast enhancement has an excellent diagnostic performance and should therefore probably be considered first-line imaging in the work-up of PE in most cases.

Comparison of V/Q SPECT and planar V/Q lung scintigraphy in diagnosing acute pulmonary embolism.

PurposePlanar ventilation/perfusion (V/Q) scintigraphy is currently the standard method for the diagnosis of pulmonary embolism (PE) in most nuclear medicine centers. However, recent studies have shown a superior sensitivity and specificity when applying V/Q single photon emission computed tomography (SPECT) in diagnosing PE. This study evaluated the diagnostic performance of three-dimensional V/Q SPECT in comparison with planar V/Q scintigraphy. Materials and methodsConsecutive patients suspected of acute PE from June 2006 to February 2008 were referred to the Department of Nuclear Medicine at Frederiksberg Hospital, Denmark to a V/Q SPECT, as the first-line imaging procedure. Patients with positive D-dimer (>0.5 mg/l) or after clinical assessment with a Wells score of more than 2 were included and had a V/Q SPECT, low-dose CT, planar V/Q scintigraphy, and pulmonary multidetector computer tomography angiography performed the same day. Ventilation studies were performed using 81mKr. Patient follow-up was at least 6 months. ResultsA total of 36 patient studies were available for analysis, of which 11 (31%) had PE. V/Q SPECT had a sensitivity of 100% and a specificity of 87%. Planar V/Q scintigraphy had a sensitivity of 64% and a specificity of 72%. ConclusionWe conclude that V/Q SPECT has a superior diagnostic performance compared with planar V/Q scintigraphy and should be preferred when diagnosing PE.

Changes in lung function of HIV-infected patients: a 4·5-year follow-up study

To investigate the development of lung function in HIV‐infected patients.

Simultaneous Hyperpolarized 13C-Pyruvate MRI and 18F-FDG PET (HyperPET) in 10 Dogs with Cancer

With the introduction of combined PET/MR spectroscopic (MRS) imaging, it is now possible to directly and indirectly image the Warburg effect with hyperpolarized 13C-pyruvate and 18F-FDG PET imaging, respectively, via a technique we have named hyperPET. The main purpose of this present study was to establish a practical workflow for performing 18F-FDG PET and hyperpolarized 13C-pyruvate MRS imaging simultaneously for tumor tissue characterization and on a larger scale test its feasibility. In addition, we evaluated the correlation between 18F-FDG uptake and 13C-lactate production. Methods: Ten dogs with biopsy-verified spontaneous malignant tumors were included for imaging. All dogs underwent a protocol of simultaneous 18F-FDG PET, anatomic MR, and hyperpolarized dynamic nuclear polarization with 13C-pyruvate imaging. The data were acquired using a combined clinical PET/MR imaging scanner. Results: We found that combined 18F-FDG PET and 13C-pyruvate MRS imaging was possible in a single session of approximately 2 h. A continuous workflow was obtained with the injection of 18F-FDG when the dogs was placed in the PET/MR scanner. 13C-MRS dynamic acquisition demonstrated in an axial slab increased 13C-lactate production in 9 of 10 dogs. For the 9 dogs, the 13C-lactate was detected after a mean of 25 s (range, 17–33 s), with a mean to peak of 13C-lactate at 49 s (range, 40–62 s). 13C-pyruvate could be detected on average after 13 s (range, 5–26 s) and peaked on average after 25 s (range, 13–42 s). We noticed concordance of 18F-FDG uptake and production of 13C-lactate in most, but not all, axial slices. Conclusion: In this study, we have shown in a series of dogs with cancer that hyperPET can easily be performed within 2 h. We showed mostly correspondence between 13C-lactate production and 18F-FDG uptake and expect the combined modalities to reveal additional metabolic information to improve prognostic value and improve response monitoring.

Silent Ischemic Heart Disease and Pericardial Fat Volume in HIV-Infected Patients: A Case-Control Myocardial Perfusion Scintigraphy Study

Objectives to determine the prevalence of asymptomatic ischemic heart disease (IHD) in HIV patients by myocardial perfusion scintigraphy (MPS) and to determine the value of coronary artery calcium score (CACS), carotid intima-media thickness (cIMT) and pericardial fat volume as screening tools for detection of IHD in subjects with HIV. Background Patients with HIV seem prone to early development of IHD. Methods 105 consecutive HIV patients (mean age 47.4 years; mean duration of HIV 12.3 years; mean CD4+ cell count 636×106/L; all receiving antiretroviral therapy) and 105 controls matched for age, gender and smoking status, without history of IHD were recruited. MPS, CACS, cIMT, pericardial fat volume, and cardiovascular risk scores were measured. Results HIV patients demonstrated higher prevalence of perfusion defects than controls (18% vs. 0%; p<0.001) despite similar risk scores. Of HIV patients with perfusion defects, 42% had a CACS = 0. CACS and cIMT were similar in HIV patients and controls. HIV patients on average had 35% increased pericardial fat volume and increased concentration of biomarkers of atherosclerosis in the blood. HIV patients with myocardial perfusion defects had increased pericardial fat volume compared with HIV patients without perfusion defects (314±43 vs. 189±12 mL; p<0.001). Conclusions HIV patients had an increased prevalence of silent IHD compared to controls as demonstrated by MPS. The finding was strongly associated with pericardial fat volume, whereas cardiovascular risk scores, cIMT and CACS seem less useful as screening tools for detection of myocardial perfusion defects in HIV patients.

SPECT/CT and pulmonary embolism

Acute pulmonary embolism (PE) is diagnosed either by ventilation/perfusion (V/P) scintigraphy or pulmonary CT angiography (CTPA). In recent years both techniques have improved. Many nuclear medicine centres have adopted the single photon emission CT (SPECT) technique as opposed to the planar technique for diagnosing PE. SPECT has been shown to have fewer indeterminate results and a higher diagnostic value. The latest improvement is the combination of a low-dose CT scan with a V/P SPECT scan in a hybrid tomograph. In a study comparing CTPA, planar scintigraphy and SPECT alone, SPECT/CT had the best diagnostic accuracy for PE. In addition, recent developments in the CTPA technique have made it possible to image the pulmonary arteries of the lungs in one breath-hold. This development is based on the change from a single-detector to multidetector CT technology with an increase in volume coverage per rotation and faster rotation. Furthermore, the dual energy CT technique is a promising modality that can provide functional imaging in combination with anatomical information. Newer high-end CT scanners and SPECT systems are able to visualize smaller subsegmental emboli. However, consensus is lacking regarding the clinical impact and treatment. In the present review, SPECT and SPECT in combination with low-dose CT, CTPA and dual energy CT are discussed in the context of diagnosing PE.

Right and left cardiac function in HIV-infected patients investigated using radionuclide ventriculography and brain natriuretic peptide: a 5-year follow-up study.

The aim of the study was to determine the incidence of myocardial dysfunction in an HIV‐infected population receiving state‐of‐the‐art treatment.

Regional Gene Expression of LOX-1, VCAM-1, and ICAM-1 in Aorta of HIV-1 Transgenic Rats

Background Increased prevalence of atherosclerotic cardiovascular disease in HIV-infected patients has been observed. The cause of this accelerated atherosclerosis is a matter of controversy. As clinical studies are complicated by a multiplicity of risk-factors and a low incidence of hard endpoints, studies in animal models could be attractive alternatives. Methodology/Principal Findings We evaluated gene expression of lectin-like oxidized-low-density-lipoprotein receptor-1 (LOX-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in HIV-1 transgenic (HIV-1Tg) rats; these genes are all thought to play important roles in early atherogenesis. Furthermore, the plasma level of sICAM-1 was measured. We found that gene expressions of LOX-1 and VCAM-1 were higher in the aortic arch of HIV-1Tg rats compared to controls. Also, the level of sICAM-1 was elevated in the HIV-1Tg rats compared to controls, but the ICAM-1 gene expression profile did not show any differences between the groups. Conclusions/Significance HIV-1Tg rats have gene expression patterns indicating endothelial dysfunction and accelerated atherosclerosis in aorta, suggesting that HIV-infection per se may cause atherosclerosis. This transgenic rat model may be a very promising model for further studies of the pathophysiology behind HIV-associated cardiovascular disease.

ANP, BNP and D-dimer predict right ventricular dysfunction in patients with acute pulmonary embolism

Background:  The aim of this study was to predict right ventricular dysfunction (RVD) using plasma concentration of D‐dimer, pro‐atrial natriuretic peptide (pro‐ANP), brain natriuretic peptide (BNP), endothelin‐1 (ET‐1) and cardiac troponin I (TNI) in patients with pulmonary embolism (PE).

Elective caesarean section increases the risk of respiratory morbidity of the newborn

Elective caesarean section upon maternal request has become more common during the last decades (1). Two surveys in the United Kingdom demonstrated that elective caesarean section upon maternal request increased from 1% in the mid 1970s and 1980s, to 30–38% in the 1990s (2). In Denmark, the overall frequency of caesarean section increased from 11.1% to 20.4% from 1982 to 2004. A Danish study stated that caesarean section upon maternal request is found as one of the main causes to the increase in caesarean section in general (3). This study aims to investigate the association among elective caesarean sections, spontaneous vaginal deliveries and neonatal respiratory morbidity in normal pregnancies expecting a normal uncomplicated birth. This is an important issue and has relevance to paediatricians when evaluating the neonatal infants after elective caesarean sections and to obstetricians when counselling mothers in choosing way of delivery. This is a retrospective study based on information from patient administrative systems and clinical databases at Hvidovre Hospital, Copenhagen University Hospital, Denmark. Information was extracted for all women giving birth in the period 1 January 2003 to 31 December 2005 at Hvidovre Hospital, Copenhagen University Hospital. The patient administrative system is used for registration of admissions and diagnoses and it is used for the economic contribution to the hospital departments. A clinical database of obstetrics keeps information regarding all deliveries at the hospital and is used for research and quality assessments. Database information was extracted, about maternal age, parity, birth weight, gestational age, umbilical cord pH, standard base excess and Apgar score. Based on the infants civil registration number, a search in the clinical database of neonatology and in the patient administrative system was performed. The latter gave information whether the infants had been admitted to a neonatal unit, the length of stay and the diagnosis at discharge. The clinical database of neonatology gave information regarding continuous positive airway pressure (CPAP) and ventilatory treatment. The criteria for inclusion were gestational age from 37 to 38 completed weeks, spontaneous vaginal delivery in cephalic presentation and elective caesarean section due to maternal request, breech presentation or transverse position. The statistical analyses were performed using SPSS 12.0 software (Chicago, IL, USA). Data on interval scales were compared using a t-test, whereas dichotomous variables were compared using a χ2-test. The level of significance was set at 0.05. A total of 16371 infants were born at Hvidovre Hospital during the 3-year period. Among those, 2174 deliveries fulfilled the criteria for inclusion and exclusion. Of these, 1680 was spontaneous vaginal deliveries and 494 elective caesarean sections. Thirty infants delivered by elective caesarean section and 37 delivered by spontaneous vaginal delivery were all transferred from the maternity ward and admitted to the neonatal unit. Overall patient characteristics are presented in Table 1. The primary diagnoses for the infants admitted to the neonatal unit are presented in Table 2. The most frequent diagnosis was respiratory morbidity, defined as persisting pulmonary hypertension of the newborn (PPHN), transient tachypnea of the newborn (TTN), pneumonia, and respiratory distress syndrome. Respiratory morbidity appears 10 times as frequent in the elective caesarean section group compared to the spontaneous vaginal delivery group (4.25% vs. 0.42%, RR 10.2, p < 0.0001) and when admitted to the neonatal unit still occurred more frequent among elective caesarean sections (70% vs. 19%, RR 3.70, p < 0.00001). Hypoglycaemia was