Radionuclide imaging of acute pulmonary embolism

Lung aeration in experimental malaria-associated acute respiratory distress syndrome by SPECT/CT analysis

Malaria-associated acute respiratory distress syndrome (ARDS) is an inflammatory disease causing alveolar-pulmonary barrier lesion and increased vascular permeability characterized by severe hypoxemia. Computed tomography (CT), among other imaging techniques, allows the morphological and quantitative identification of lung lesions during ARDS. This study aims to identify the onset of malaria-associated ARDS development in an experimental model by imaging diagnosis. Our results demonstrated that ARDS-developing mice presented decreased gaseous exchange and pulmonary insufficiency, as shown by the SPECT/CT technique. The pulmonary aeration disturbance in ARDS-developing mice on the 5th day post infection was characterized by aerated tissues decrease and nonaerated tissue accumulation, demonstrating increased vascular permeability and pleural effusion. The SPECT/CT technique allowed the early diagnosis in the experimental model, as well as the identification of the pulmonary aeration. Notwithstanding, despite the fact that this study contributes to better understand lung lesions during malaria-associated ARDS, further imaging studies are needed.

The conclusions drawn from ventilation/perfusion single-photon emission computed tomography compared with lung perfusion single-photon emission computed tomography and chest radiography in patients with suspected pulmonary thromboembolism

PURPOSE

There are conflicting results from studies on whether ventilation scintigraphy can be safely omitted or replaced by chest radiography. These studies were based on planar ventilation/perfusion (V/Q) scintigraphy. We evaluated the value of the ventilation single-photon emission computed tomography (SPECT) on the final conclusion drawn from a V/Q SPECT and the possible role of the chest radiography as a surrogate for the ventilation SPECT.

PATIENTS AND METHODS

Raw data of V/Q SPECT images and chest radiography acquired within 48 h over an 18-month period were retrieved, reprocessed and reviewed in batches. The ventilation SPECT, perfusion SPECT and chest radiography were reviewed separately and in combination. Data on the presence and nature of defects and chest radiography abnormalities were recorded. The V/Q SPECT images were interpreted using the criteria in the EANM guideline and the perfusion SPECT and chest radiography images were interpreted using the PISAPED criteria. Agreement between the diagnosis on the V/Q SPECT review and the perfusion SPECT and chest radiography review was analysed.

RESULTS

Overall, 21.1% of the patients were classified as 'PE present' on the V/Q SPECT review, whereas 48.9% were classified as 'PE present' on the perfusion SPECT and chest radiography review. Only 5.4% of defects observed on ventilation SPECT had matched chest radiography lung field opacity.

CONCLUSION

Our study showed that the omission of a ventilation SPECT led to a high rate of false-positive diagnoses and that the ventilation scan cannot be replaced by a chest radiography.

The prevalence and radiological findings of pulmonary embolism in HIV-positive patients referred for computed tomography pulmonary angiography in the Western Cape of South Africa

Aim:

To provide imaging data and report associations between human immunodeficiency virus (HIV), tuberculosis (TB) and pulmonary embolism (PE) in a South African population that underwent computed tomography pulmonary angiography (CTPA) for suspected PE.

Methods:

A validated Qanadli severity scoring system for PE was used for 164 CTPA scans, and parenchymal, pleural and cardiovascular complications were reported. Serological confirmation of HIV testing and microbiological confirmation of TB were recorded.

Results:

Prevalence of PE in the CTPA population was 26% (95% CI: 19.67–33.65%). HIV-positive prevalence in patients with PE was 67% (95% CI: 48.17–82.04%), however it was not statistically significantly different when compared with the patients without PE (p = 1). HIV-positive patients had more extensive partial thrombus in the right middle lobe (p = 0.045), but no other differences when compared with HIV-negative patients. TB prevalence in patients with PE was 57% (95% CI: 34.49–76.81%). This was statistically significantly different when compared with the patients without PE (p = 0.073 at the 10% level). Prevalence of TB co-morbidity in the HIV-positive group with proven PE was 71% (95% CI: 41.90– 91.61%), however there was no statistically significant difference in comparison with the HIV-negative patients with TB and PE (p= 0.305).

Conclusion:

The high number of patients presenting for CTPA who were HIV infected (and also infected with TB) highlights that PE evaluation should include severity/extent of the disease, as these patients may have more severe disease in specific lung lobes. The use of a validated scoring system, such as the Qanadli score, when reporting PE may have a profound effect on patient risk stratification, management and prognosis and would also provide a system for collecting larger volumes of data for analysis.

Estimated incidence of acute pulmonary embolism in a Korean hospital

Patients with acute pulmonary embolism (PE) were identified retrospectively from patients hospitalized during a 2-year period from 2005 to 2007. Among adult patients (≥20 years), the incidence of established acute PE was 88 (0.17%) of 50 882 in Dongsan Hospital. The incidence of acute PE at Dongsan Hospital was 26% lower than that at Henry Ford Hospital (P < .01). Among patients more than 50 years of age, PE was more frequent in women (0.32%; 95% CI, 0.24-0.4) than in men (0.15%; 95% CI, 0.1-0.21; P < .01). Among all patients with PE older than 20 years of age, 68 (0.21%) of 31 869 (95% CI, 0.17-0.26) were from the medical service and 18 (0.08%) of 23 139 (95% CI, 0.04-0.11; P < .01) were from the surgical service. The estimated incidence of PE in a university teaching hospital in Korea was 0.17%, it was about two thirds of that in North America.

Ventilation/perfusion lung scintigraphy: what is still needed? A review considering technetium-99m-labeled macro-aggregates of albumin

Lung perfusion scintigraphy (LPS) with technetium-99m-labeled macro-aggregates of albumin (Tc-99m-MAA) is well established in the diagnostic of pulmonary embolism (PE). In the last decade, it was shown that single-photon emission computer tomography (SPECT) acquisition of LPS overcame static scintigraphy. Furthermore, there are rare indications for LPS, such as preoperative quantification of regional lung function prior to lung resection or transplantation, optimization of lung cancer radiation therapy, quantification of right-left shunt, planning of intra-arterial chemotherapy, and several rare indications in pediatrics. Moreover, LPS with Tc-99m-MAA is a safe method with low radiation exposure. PE can also be diagnosed by spiral computer tomography (CT), ultrasound, magnetic resonance angiography, or pulmonary angiography (PA, former gold standard). The present review considers all these methods, especially spiral CT, and compares them with LPS with respect to sensitivity and specificity and gives an overview of established and newer publications. It shows that LPS with Tc-99m-MAA represents a diagnostic method of continuing value for PE. In comparison with spiral CT and/or PA, LPS is not to be defeated as mentioned also by the most actual Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II reports. This applies in particular to chronic or recurring embolisms, whereas currently spiral CT may be of greater value for major or life-threatening embolisms. At present, LPS cannot be replaced by other methods in some applications, such as pediatrics or in the quantification of regional pulmonary function in a preoperative context or prior to radiation therapy. LPS still has a place in the diagnostics of PE and is irreplaceable in several rare indications as described earlier.

Effect of shed blood retransfusion on pulmonary perfusion after total knee arthroplasty: a prospective controlled study

Postoperative shed blood retransfusion (autotransfusion) is a commonly used salvage method following major surgical operations, such as total knee arthroplasty (TKA). The systemic effects of shed blood are still unclear. We studied the effect of residual substances in the retransfused shed blood, on lung perfusion after TKA. Fifteen unilateral and one bilateral TKAs were performed with autotransfusion (the study group) and 15 unilateral and three bilateral TKAs were performed in a control group. Lung X-rays, arterial blood gases (ABG), D-dimer values, and lung perfusion scintigraphies were performed preoperatively and postoperatively. A mean of 300.0 +/- 335.6 ml of bank blood was needed in the autotransfusion group and a mean of 685.7 +/- 365.5 ml of bank blood was needed in the control group (p=0.001). There was a postoperative segmental perfusion defect at the lateral segment of the superior lobe of the left lung in one patient of the control group and he also had risk factors for thrombosis. Although both groups had a decrease in lung perfusion postoperatively, there were no significant differences among the groups regarding the lung perfusion scintigraphy, chest X-rays, ABG, and D-dimer values. In conclusion, although pulmonary perfusion diminishes following TKA, shed blood retransfusion does not add any risk to pulmonary perfusion.

Depiction of residual emboli following pulmonary embolism with thrombotic scintigraphy

BACKGROUND

In the treatment of pulmonary embolism (PE), the presence of residual emboli is known to seriously affect the recurrence and prognosis. We attempted to depict the residual emboli in the subacute stage of PE using indium-111-oxine labeled platelet scintigraphy (In-plt).

METHODS

In-plt was performed on 22 patients with PE who showed an improvement according to lung perfusion scintigraphy. Their accumulation was assessed along with the blood coagulation ability measured on the same day. In addition, radioisotope venography (RI-veno) was performed simultaneously with In-plt to measure the circulatory findings in the lower limb for comparison. All patients received systemic heparin during the acute stage and received warfarin at the time of testing.

RESULTS

Accumulation of In-pit was observed in 7 patients (32%), and positive signals were found in the lower limbs or pelvic cavity in all cases. Two patients were suspected of having poor lower limb circulation from their RI-veno findings, and these findings were largely consistent with the areas of In-plt accumulation.

DISCUSSION

Some emboli persist after extensive anti-coagulation therapy. The use of In-pit is effective in determining the therapeutic measures and assessing the prognosis as this method allows us to clearly depict the existence of such emboli.