Age-related incidence of pulmonary embolism and additional pathologic findings detected by computed tomography pulmonary angiography

Objective

To compare the incidence of pulmonary embolism (PE) and additional pathologic findings (APF) detected by computed tomography pulmonary angiography (CTPA) according to different age-groups.

Materials and methods

1353 consecutive CTPA cases for suspected PE were retrospectively reviewed. Patients were divided into seven age groups: ≤29, 30–39, 40–49, 50–59, 60–69, 70–79 and ≥80 years. Differences between the groups were tested using Fisher's exact or chi-square test. A p-value < 0.0024 indicated statistical significance when Bonferroni correction was used.

Results

Incidence rates of PE ranged from 11.4% to 25.4% in different age groups. The three main APF were pleural effusion, pneumonia and pulmonary nodules. No significant difference was found between the incidences of PE in different age groups. Furthermore, APF in different age groups revealed no significant differences (all p-values > 0.0024).

Conclusion

The incidences of PE and APF detected by CTPA reveal no significant differences between various age groups.     

Dual Energy CT lung perfusion imaging--correlation with SPECT/CT

Objective

Aims were (1) to determine the diagnostic accuracy of Dual Energy CT (DECT) in the detection of perfusion defects and (2) to evaluate the potential of DECT to improve the sensitivity for PE.

Methods

15 patients underwent Dual Energy pulmonary CT angiography (DE CTPA) and a combination of lung perfusion SPECT/CT and ventilation scintigraphy. CTPA and DE iodine distribution maps as well as perfusion SPECT/CT and inhalation scintigrams were reviewed for pulmonary embolism (PE) diagnosis. DECT and SPECT perfusion images were assessed regarding localization and extent of perfusion defects. Diagnostic accuracy of DE iodine (perfusion) maps was determined with reference to SPECT/CT. Diagnostic accuracies for PE detection of DECT and of SPECT/CT with ventilation scintigraphy were calculated with reference to the consensus reading of all modalities.

Results

DE CTPA had a sensitivity/specificity of 100%/100% for acute PE, while the combination of SPECT/CT and ventilation scintigraphy had a sensitivity/specificity of 85.7%/87.5%. For perfusion defects, DECT iodine maps had a sensitivity/specificity of 76.7% and 98.2%.

Conclusion

DECT is able to identify pulmonary perfusion defects with good accuracy. This technique may potentially enhance the diagnostic accuracy in the assessment of PE.     

Improved image quality and low radiation dose with hybrid iterative reconstruction with 80 kV CT pulmonary angiography

Objectives

To determine the impact of hybrid iterative reconstruction (HIR) on image quality in 80 kV CT pulmonary angiography (CTPA) in comparison to filtered-back-projection (FBP).

Methods

Fifty patients (body weight <80 kg) with suspected pulmonary embolism (PE) underwent CTPA at 80 kV (mean CTDIvol, 2.3 mGy; effective dose, 1.2 mSv). The raw data were reconstructed using FBP and three increasing HIR levels. Two radiologists assessed image quality and image noise. Conspicuity of PE was assessed in central, segmental, and subsegmental arteries. CT attenuation of pulmonary arteries, objective image noise (OIN) and contrast-to-noise ratios (CNR) were assessed.

Results

With each HIR level, a significant decrease in subjective and objective image noise was achieved with a reduction of OIN up to 46% in comparison with FBP. CNR significantly increased with the application of HIR compared to FBP. Image quality was rated significantly higher at HIR reconstructions in comparison with FBP. Diagnosis of PE was feasible with each data set; however, conspicuity of central and segmental PE significantly improved with the use of HIR.

Conclusions

Eighty kilovoltage CTPA with HIR provides improved image quality and conspicuity of pulmonary embolism enabling low dose CTPA protocols close to 1 mSv in patients weighing less than 80 kg.     

Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results

Purpose

Computed tomography pulmonary angiography (CTPA) is considered as clinical gold standard for diagnosing pulmonary embolism (PE). Whereas conventional CTPA only offers anatomic information, dual energy CT (DECT) provides functional information on blood volume as surrogate of perfusion by assessing the pulmonary iodine distribution. The purpose of this study was to evaluate the feasibility of lung perfusion imaging using a single-tube DECT scanner with rapid kVp switching.

Materials and methods

Fourteen patients with suspicion of acute PE underwent DECT. Two experienced radiologists assessed the CTPA images and lung perfusion maps regarding the presence of PE. The image quality was rated using a semi-quantitative 5-point scale: 1 (=excellent) to 5 (=non-diagnostic). Iodine concentrations were quantified by a ROI analysis.

Results

Seventy perfusion defects were identified in 266 lung segments: 13 (19%) were rated as consistent with PE. Five patients had signs of PE at CTPA. All patients with occlusive clots were correctly identified by DECT perfusion maps. On a per patient basis the sensitivity and specificity were 80.0% and 88.9%, respectively, while on a per segment basis it was 40.0% and 97.6%, respectively. None of the patients with a homogeneous perfusion map had an abnormal CTPA. The overall image quality of the perfusion maps was rated with a mean score of 2.6 ± 0.6. There was a significant ventrodorsal gradient of the median iodine concentrations (1.1 mg/cm³ vs. 1.7 mg/cm³).

Conclusion

Lung perfusion imaging on a DE CT-system with fast kVp-switching is feasible. DECT might be a helpful adjunct to assess the clinical severity of PE.     

Dual-energy CT based vascular iodine analysis improves sensitivity for peripheral pulmonary artery thrombus detection: An experimental study in canines

Purpose

To evaluate the performance of dual-energy CT (DECT) based vascular iodine analysis for the detection of acute peripheral pulmonary thrombus (PE) in a canine model with histopathological findings as the reference standard.

Materials and methods

The study protocol was approved by our institutional animal committee. Thrombi (n = 12) or saline (n = 4) were intravenously injected via right femoral vein in sixteen dogs, respectively. CT pulmonary angiography (CTPA) in DECT mode was performed and conventional CTPA images and DECT based vascular iodine studies using Lung Vessels application were reconstructed. Two radiologists visually evaluated the number and location of PEs using conventional CTPA and DECT series on a per-animal and a per-clot basis. Detailed histopathological examination of lung specimens and catheter angiography served as reference standard. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of DECT and CTPA were calculated on a segmental and subsegmental or more distal pulmonary artery basis. Weighted κ values were computed to evaluate inter-modality and inter-reader agreement.

Results

Thirteen dogs were enrolled for final image analysis (experimental group = 9, control group = 4). Histopathological results revealed 237 emboli in 45 lung lobes in 9 experimental dogs, 11 emboli in segmental pulmonary arteries, 49 in subsegmental pulmonary arteries, 177 in fifth-order or more distal pulmonary arteries. Overall sensitivity, specificity, accuracy, PPV, and NPV for CTPA plus DECT were 93.1%, 76.9%, 87.8%, 89.4%, and 84.2% for the detection of pulmonary emboli. With CTPA versus DECT, sensitivities, specificities, accuracies, PPVs, and NPVs are all 100% for the detection of pulmonary emboli on a segmental pulmonary artery basis, 88.9%, 100%, 96.0%, 100%, and 94.1% for CTPA and 90.4%, 93.0%, 92.0%, 88.7%, and 94.1% for DECT on a subsegmental pulmonary artery basis; 23.8%, 96.4%, 50.4%, 93.5%, and 36.7% for CTPA and 95.9%, 75.5%, 88.2%, 86.5%, and 91.9% on a sub-subsegmental and more distal pulmonary artery basis, respectively. Good inter-modality (κ = 0.65, P < 0.001) and inter-reader (κ = 0.70, P < 0.001) agreement were observed.

Conclusion

With histopathological findings as the reference standard, DECT based vascular iodine analysis improves the sensitivity for detecting peripheral PE compared with CTPA, albeit at the price of decreased specificity and PPV.     

Low yield of ventilation and perfusion imaging for the evaluation of pulmonary embolism after indeterminate CT pulmonary angiography

Purpose

Ventilation and perfusion (VQ) imaging is common following suboptimal CT pulmonary angiogram (CTPA) for pulmonary embolism (PE) evaluation; however, the results of this diagnostic pathway are unclear. The purpose of our study is to determine the incidence of PE diagnosed on VQ scans performed in patients with suboptimal CTPAs.

Methods

One hundred twenty-two suboptimal CTPAs with subsequent VQ scans within 1 week were retrospectively identified. VQ reports utilizing modified ?prospective investigation of pulmonary embolism diagnosis (PIOPED) and prospective investigative study of acute pulmonary embolism diagnosis (PISAPED) criteria were evaluated for presence of PE; intermediate probability, high probability, and PE present were considered PE positive. Three hundred consecutive reports of each diagnostic CTPA and diagnostic VQ studies were reviewed to estimate baseline PE positive rates at our institution. These were compared to the positive VQ scan rate after suboptimal CTPA by Fisher’s exact test. Reported reason for suboptimal CTPA was noted. When contrast bolus timing was suboptimal, we measured main pulmonary artery (mPA) Hounsfield units (HU). Potential alternative diagnoses in CTPA reports were noted.

Results

97.5% (119/122) of VQ scans following suboptimal CTPA were negative for PE, and 2.5% (3/122) were positive for PE. This was significantly lower than baseline PE positive rate of 10.7% (32/300, p < 0.01) for VQ imaging, and 10.3% (31/300, p < 0.01) for CTPA at our institution. Most (79.5%) CTPAs were suboptimal due to contrast timing. Average mPA density in these cases was 164 ± 61 HU. Most of these studies ruled out central PE. Potential alternative diagnosis was reported in 34/122 (28%) of suboptimal CTPAs, for which pneumonia accounted 59%.

Conclusion

There is very low incidence of PE diagnosed on VQ imaging performed after suboptimal CTPA. This may be attributed to the ability of most suboptimal CTPAs to rule out central PE.

     

Prospectively ECG gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: impact on cardiac related motion artifacts and patient radiation dose

Objective

To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose.

Subjects and methods

Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters.

Results

Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution.

Conclusion

Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.     

Prediction of short term outcome of pulmonary embolism: Parameters at 16 multi-detector CT pulmonary angiography

Purpose

To evaluate the accuracy of computed tomography pulmonary angiography (CTPA) parameters, for predicting short-term mortality in patients with acute pulmonary embolism (PE).

Materials and methods

Thirty-two patients with proven PE had CT pulmonary angiography were included in the study. The clot burden using the Qanadli score (QS), and the right ventricular dysfunction (RVD) parameters were assessed on CT by calculating right ventricular/left ventricular (RV/LV) diameter ratios, interventricular septum abnormality, inferior vena cava contrast reflux, azygous vein and superior vena cava measures. Contrast density in pulmonary artery and descending aorta was evaluated for all patients. Patients were followed up for 30 days and then classified as survivors or non survivors.

Results

Thirty-two patients were included in the study, 23 (71.8%) of them were classified as survivors, and the other nine (28.1%) patients died within the first month (non survivors). There was a positive, but weak correlation between the Qanadli score and the short term mortality (P value = 0.05). There was a statistically significant relationship between the RV/LV ratio and PE-related mortality, with a P value < 0.001. Also, there was a good correlation between degree of IVC reflux and PE outcome (P < 0.001). The PA/AO diameter ratio, SVC diameter and azygous vein diameter showed no statistically significant difference between survivors and non survivors.

Conclusions

CTPA findings that may predict short term mortality are the high grades of inferior vena cava reflux, RV/LV diameter ratio more than 1.2, and clot burden >18 according to the Qanadli score and to a lesser degree the interventricular septum abnormality.     

Comparison of automated 4-chamber cardiac views versus axial views for measuring right ventricular enlargement in patients with suspected pulmonary embolism

Purpose

Compare the right ventricle to left ventricle (RV/LV) diameter ratio obtained from axial pulmonary CT angiograms (CTPA) with those derived from automatically generated 4-chamber (4-CH) reformats in patients with suspected pulmonary embolism (PE).

Methods

In this institutional review board-approved study we included 120 consecutive non ECG-gated CTPA from 3 institutions (mean age 60 ± 16 years; 71 women). Twenty 64-slice CTPA with PE and 20 without PE were selected per institution. For each patient the RV/LV diameter ratio was obtained from both axial CTPA images and automatically generated 4-CH reformats. Measurements were performed twice in two separated sessions by 2 experienced radiologists and 2 residents. The differences between the measurements on both views were evaluated.

Results

The 4-CH view was successfully obtained in 113 patients. The mean axial and 4-CH diameter ratios were comparable for three of the four readers (p = 0.56, p = 0.13, p = 0.08). Although the mean diameters (1.0 and 1.03 respectively) for one resident were significantly different (p = 0.013), the difference of 0.03 seems negligible in clinical routine. Three readers achieved equally high intra-reader agreements with both measurements (ICCs of 0.94, 0.95 and 0.96), while one reader showed a different variability with ICCs of 0.96 for the axial view and 0.91 for the 4-CH view. The inter-reader agreement was equally high for both measurement types with ICCs of 0.95 and 0.94, respectively.

Conclusion

In patients with suspected PE, RV/LV diameters ratio can be measured with the same reproducibility and accuracy using an automatically generated 4-CH view compared to the axial view.     

Patient-centered clinical impact of incidentally detected abnormalities on chest CT scans

Purpose

To demonstrate the spectrum of incidental findings on chest CT scans and to evaluate the clinical impact of significant different abnormalities on patient management.

Materials and methods

This retrospective study included incidental findings on chest CT scans from an adult patient population, performed at the University of Washington, within a 10 month period. After exclusion of repetitive findings, 113 patients (50 males and 63 females, age 18–96 years, mean = 57.3 years) demonstrated 163 uniquely different findings. We determined the clinical significance according to the need for further workup and/or therapy. The gold standard for diagnosis was either by pathologic proof, follow up CT, or other imaging modalities.

Results

38 different findings were judged clinically significant (10.4%) requiring further workup and/or therapy in 9.6% and 7.1%, respectively. The anatomic site of disease was: intra-thoracic (n = 27, 71.1%), extra-thoracic (n = 5, 13.1%), lower neck (n = 3, 7.9%), and upper abdomen (n = 3, 7.9%). They included 12 unique malignant pathologies (31.6%), and 26 non-malignant findings (68.4%).

Conclusion

The clinically significant different incidental abnormalities on chest CT scans represented 10.4% of all incidental findings, 3.3% were due to malignancies. The clinical impact of incidental abnormalities on chest CT may be of utmost importance on patient care.     

Acute and subacute dual energy CT findings of pulmonary embolism in rabbits: correlation with histopathology

Objective

The purpose of this study was to describe quantitative dual energy CT (DECT) findings and their accuracy in the detection of acute and subacute pulmonary embolism (PE) in rabbits.

Methods

Pulmonary emboli were created in 24 rabbits by gelatin sponge femoral vein injection. Conventional CT pulmonary angiography (CTPA) and DECT were obtained at either 2 h, 1 day, 3 days or 7 days after embolisation (n=6 rabbits for each time point). The location and number of PEs in the different stages were recorded at CTPA and iodine maps from DECT on a per-lobe basis. With histopathology as the reference standard, sensitivity and specificity of CTPA and DECT were calculated. CT and iodine map overlay values of the embolic and non-embolic areas were measured for each scan.

Results

With histopathology as the reference standard, the overall sensitivity and specificity of CTPA were 98% and 100% and those of iodine maps were 100% and 95%, respectively. Conventional CT and iodine map values of the embolised and non-embolised areas were significantly different between 2 h and 1 day (p<0.001), but not between 3 days and 7 days (p>0.05). A statistical difference was found for overlay values measured in the embolic and non-embolic regions for four groups.

Conclusion

Iodine maps derived from DECT show alterations in lung perfusion for acute and subacute PE in an experimental rabbit model and show comparable sensitivity for PE detection and conventional CTPAIn the USA, more than 650 000 cases of pulmonary embolism (PE) occur each year, resulting in as many as 300 000 annual fatalities [1,2]. Despite the high morbidity, the diagnosis of PE may be delayed in the absence of typical clinical symptoms or when emboli are subsegmental and such scenarios may delay the treatment and increase the mortality of PE. Imaging plays an important role in the diagnosis and follow-up of PE. With improvements in multidetector row CT, CT pulmonary angiography (CTPA) has largely replaced digital subtraction angiography (DSA) for the diagnosis and follow-up of PE and has been recommended as the reference of standard for diagnosis of acute PE [3]. However, CTPA has shortcomings, such as a limited sensitivity to detect peripheral or subsubsegmental emboli of the pulmonary artery and an inability to show lung perfusion impairment resulting from acute or chronic PE.With the development of dual source CT (DSCT), in which two orthogonally mounted detectors and tubes arrays operate simultaneously and can be set to different tube potentials to allow for dual energy CT (DECT) acquisitions with minimal patient motion registration artefact, DECT imaging has been used to investigate iodine distribution maps in clinical and pre-clinical studies [4-13]. Such iodine maps, which have been termed blood flow imaging (BFI), have been shown to be valuable supplements to conventional anatomic CTPA for the evaluation of distal pulmonary artery emboli [4-13]. Many studies have focused on the feasibility or diagnostic accuracy of DECT iodine maps to improve the detection of PE, with CTPA, scintigraphy or histopathology as a reference standard in the clinical and experimental studies [5-13], or the evaluation of image quality of dual energy CTPA [14,15]. However, to the best of our knowledge, there are no reports that describe the evolution of CT and DECT imaging findings of PE over time after an embolic event with histopathological correlation. Histopathology correlation is most ethically obtained using an animal model. Therefore, we evaluated DECT findings with histopathology correlation in a rabbit model of PE with different time delays after embolisation and assessed the diagnostic accuracy of DECT in the detection of PE at these different time points.     

Does lung perfusion scintigraphy continue to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography era?

Objective

Acute pulmonary embolism (PE) is a life-threatening disorder with high mortality. A prompt diagnosis and treatment is essential for reducing the mortality rate. The purpose of the study is to evaluate if lung perfusion scintigraphy (LPS) continues to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography (CTPA) era.

Methods

For this study, 1183 patients who had been subjected to LPS were retrospectively evaluated and classified into the following groups: A (positive LPS), B (negative LPS) and C (indeterminate LPS). Patients were further classified into A1 (‘PE likely’ and LPS-negative), B1 (PE unlikely and LPS-positive) and C1 (PE likely and indeterminate LPS) by combining the LPS findings and the clinical pretest probability (cpp). Subgroups A1, B1 and C1 underwent additional CTPA.

Results

Groups A, B, and C included 1086/1183, 69/1183 and 28/1183 patients, respectively. The proportion of patients with inconsistent cpp LPS findings who underwent additional CTPA was 106/1183 patients: subgroup A1 (n?=?73), B1 (n?=?21), and C1 (n?=?12). In subgroup A1, CTPA was negative in 61/73, non-diagnostic in 12/73 and positive in 0/73 patients. In subgroup B1, CTPA excluded PE in 2/21, non-diagnostic in 3/21 and positive in 16/21 patients. In group C1, CTPA was negative in 8/12, positive in 2/12 and non-diagnostic in 2/12 patients.

Conclusion

In the CTPA era, LPS continues to have a role in the clinical management of patients suspected of PE.

     

A retrospective study of the value of indirect CT venography: a British perspective

Objective

The aim of this study was to establish the value of indirect CT venography (CTV) in clinical practice within the UK.

Methods

804 combined CT pulmonary angiogram and CTV studies were retrospectively reviewed. CTV was performed 180 s after the injection of contrast using an incremental technique with a 5-mm collimation and a 5-cm interspace between images extending from the iliac crests to the tibial plateaus.

Results

12.9% of studies had isolated pulmonary emboli (PE), 3.0% had both a PE and deep vein thrombosis (DVT) and 1.1% had an isolated DVT. The proportion of positive cases diagnosed by CTV alone was 6.6%.

Conclusion

In a UK-based practice, the incidence and the proportion of isolated DVT diagnosed by CTV are lower than expected from published data. An analysis of possible causes for this is made within the paper.More than 250 000 cases of pulmonary embolism were identified in the UK between 1996 and 2006, yet the accurate diagnosis of this condition remains problematic [1]. Autopsy studies indicate that 88% of pulmonary emboli (PE) are unsuspected clinically prior to death. Although the majority of these PE are an incidental complication of an underlying comorbid condition, less than half of cases of fatal PE are correctly diagnosed ante-mortem [2,3]. It is accepted that PE originate from distant sites of venous thrombosis and that both PE and deep vein thrombosis (DVT) are facets of the same disease process, with the majority of DVT arising within the lower limb veins. The evaluation of the presence of DVT is therefore considered part of the investigation of PE, and the presence of DVT in the absence of radiological evidence of PE can be accepted as surrogate evidence of venous thromboembolism (VTE). Lower limb indirect CT venography (CTV) may be added to CT pulmonary angiography (CTPA) to identify the presence of DVT, but this is at the expense of an increased examination time and an increased radiation dose, particularly to the reproductive organs. The prospective investigation of the PE diagnosis II study demonstrated the addition of CTV to CTPA increased the sensitivity for detection of PE from 83% to 90% [4]. Despite this, the routine addition of CTV to CTPA is not recognised in current British Thoracic Society guidelines, and it is not known how many centres in the UK have adopted this technique [5].The aim of this study is to establish the incremental value of CTV in clinical practice within a British institution and ascertain whether factors such as image quality significantly influence the value of the examination. To our knowledge this is the first large British study of the value of CTV in the investigation of PE.     

CT pulmonary angiogram quality comparison between early and later pregnancy

Purpose

Pregnancy increases the risk for thromboembolic disease. CT pulmonary angiogram (CTPA) is widely used for the diagnosis of pulmonary embolus (PE); however, a significant number of scans are suboptimal or non-diagnostic in pregnant patients. This phenomenon is attributed to physiology during the gravid state. The aim of this study is to examine whether all stages of pregnancy are similarly at risk for suboptimal scans.

Methods

Pregnant patients who had CTPA scans between February 2008 and November 2014 were included. The attenuation in the major pulmonary arteries was compared among patients and controls. An attenuation of 200 Hounsfield units (HU) was used as a cutoff between adequate and suboptimal studies. Statistical analysis compared attenuation means and number of arteries with adequate versus suboptimal attenuation.

Results

Forty patients were included in the study. Nine were at or below 13 weeks of pregnancy and 31 between week 14 and term. A control group of 14 non-pregnant women of similar age were also included. All arteries showed a significantly higher attenuation in early pregnancy and in the control group compared to later in pregnancy, p < 0.05. Fewer suboptimal opacified arteries were found in early pregnancy (11.1%) and controls (5.7%) compared to later in pregnancy (33.3%), p < 0.01.

Conclusion

Patients in early pregnancy are more likely to have a technically successful CTPA scan compared to later in pregnancy and show similar opacification to non-pregnant women. This suggests a possible paradigm shift from the current approach to suspected PE in pregnant patients.

     

Thrombus load and acute right ventricular failure in pulmonary embolism: correlation and demonstration of a “tipping point” on CT pulmonary angiography

Objectives

The aim of this study was to determine the correlation between increasing pulmonary embolism thrombus load and right ventricular (RV) dilatation as demonstrated by CT pulmonary angiography (CTPA) and to assess the thrombus load threshold which indicates impending RV decompensation.

Methods

2425 consecutive CTPAs were retrospectively analysed. Thrombus load using a modified Miller score (MMS), RV to left ventricular (RV:LV) ratio, presence of septal shift, and pulmonary artery and aorta size were analysed in 504 positive CTPA scans and a representative cohort of 100 negative scans. Results were correlated using non-parametric analysis (two-tailed t-test or χ² test) and Pearson’s rank correlation.

Results

Increasing thrombus load correlated with a higher RV:LV ratio, with a statistically significant difference in RV:LV ratios between the negative and positive pulmonary embolism (PE) cohorts. Larger thrombus loads (MMS ≥12 vs MMS <12) were strongly correlated with RV strain (mean RV:LV ratio, 1.323 vs 0.930; p<0.0001). Smaller thrombus loads had no significant influence on RV strain. Septal shift was also more likely with an MMS of ≥12, as was an increase in pulmonary artery diameter (r=0.221, p<0.001).

Conclusion

With increasing thrombus load in PE, there is CTPA evidence of RV decompensation with an MMS threshold of 12. This suggests a “tipping point” beyond which RV decompensation is more likely to occur. This is the first study to describe this tipping point between a thrombus load of MMS >12 and an increase in RV:LV ratio. This finding may help to improve risk stratification in patients with acute PE diagnosed by CTPA.Acute pulmonary embolism (PE) remains a diagnostic challenge for physicians and accounts for significant morbidity and mortality in hospitalised patients. In the United Kingdom, the incidence of proven PE is 60–70 per 100 000 in the population and mortality rates range from 6% to 15%. Clinical manifestations vary widely, from asymptomatic patients with small peripheral emboli to patients who present with circulatory collapse and large thromboembolic loads who may warrant thrombolysis. Between these extremes, there is a significant group presenting with PE who have apparent clinical haemodynamic stability but demonstrate radiological findings (e.g. via echocardiography or CT pulmonary angiography) or biomarkers [such as B-type natriuretic peptide (BNP) or troponin] of right heart strain, in whom the prognosis may be poorer and for whom the role of thrombolysis has not been established [1-4]. Studies to date have demonstrated that right heart strain is associated with higher mortality than no right heart strain [5,6], and CT assessment of right heart strain correlates with echocardiographic findings [7].CT pulmonary angiography (CTPA) has been established as the imaging modality of choice for the initial diagnosis of pulmonary thromboembolism [8,9], and is also used for assessing right ventricular (RV) afterload [10,11]. In addition, it enables quantification of thrombus load, for which a variety of scoring systems are available. These include the modified Miller score (MMS), a catheter pulmonary angiography score [12] adapted for CTPA by Bankier et al [13], and more complex systems such as the Qanadli and Mastora scores [14,15]. The aim of this study was to determine if there is a correlation between increasing thrombus load using MMS and RV dilatation as a predictor of RV failure according to CTPA findings.     

Does the anatomic distribution of acute pulmonary emboli at MDCT pulmonary angiography in oncology-population differ from that in non-oncology counterpart?

Objective

To compare the prevalence and the anatomic distribution of acute PE in oncology patients with those of non oncology patients using multidetector CT (MDCT) pulmonary angiography.

Material and methods

We prospectively reviewed 80 consecutive patients having pathologically proven neoplasms and clinically suspected to have acute PE. Similarly, the other group included 80 consecutive age-matched patients with the clinical suspicion of acute PE, nonetheless, with irrelevant oncologic history. All patients underwent MDCT pulmonary angiography. The PE involvement according to pulmonary arterial level was classified. Lobar location was also recorded using standard nomenclature.

Results

Twenty six patients (33%) of the 80 oncology patients compared to 19 patients (24%) of the 80 non oncology group had acute PE at pulmonary MDCT angiographic examinations. Among the oncology patients, acute PE was located in the main pulmonary artery in 7 (13%), the lobar pulmonary artery in 22 (40%), the segmental pulmonary artery in 17 (31%) and the subsegmental pulmonary artery in 9 (16%) patients. Whereas in the non oncology group, the level of involvement of PE was the main pulmonary artery in 4 (10%) patients, the lobar pulmonary artery in 17 (40%), the segmental pulmonary artery in 15 (36%) and the subsegmental pulmonary artery in 6 (14%). Alternatively, there was a lower lobar predominance in both groups.

Conclusion

The prevalence of acute PE is more common among oncology patients than previously reported and has a slight predilection to a central distribution.     

Software-Based Hybrid Perfusion SPECT/CT Provides Diagnostic Accuracy When Other Pulmonary Embolism Imaging Is Indeterminate

Purpose

To investigate the diagnostic performance of perfusion single-photon emission computed tomography/computed tomography (Q-SPECT/CT) in patients suspected to have pulmonary embolism (PE) but with indeterminate computed tomographic pulmonary angiography (CTPA) or planar ventilation/perfusion (V/Q) scans.

Methods

This retrospective study included two groups of patients. Group I consisted of 49 patients with nondiagnostic CTPA. These 49 patients underwent subsequent V/Q scans. Further Q-SPECTs were obtained in patients with indeterminate planar images and fused with existing CTPA. Group II consisted of 182 non-CTPA patients with indeterminate V/Q scans. These 182 patients underwent further Q-SPECT and separate noncontrast low-dose CT chest. Fusion Q-SPECT/CT scans were obtained through FDA-approved software and interpreted according to published criteria as positive, negative, or indeterminate for PE. Upon retrospective analyses, the final diagnosis was made using composite reference standards including all available clinical and imaging information for at least 6-month follow-up.

Results

In group I patients, 1 was positive, 24 were negative, and another 24 (49 %, 24/49) were indeterminate. In the subsequent 24 Q-SPECT/CTPAs, 4 were positive, 19 were negative, and 1 was indeterminate (4.2 %, 1/24). In group II patients, 9 (4.9 %, 9/182) were indeterminate, 33 were positive, and 140 were negative. The combined nondiagnostic rate for Q-SPECT/CT was only 4.9 % (10/206). There was six false-negative and one false-positive Q-SPECT/CT examinations. The sensitivity, specificity, and positive and negative predictive value of Q-SPECT/CT were 85.7 % (36/42), 99.4 % (153/154), 97.3 % (36/37) and 96.2 % (153/159), respectively.

Conclusions

Q-SPECT/CT improves the diagnostic rate with promising accuracy in diagnosing PE that yields a satisfactory clinical verdict, especially when the CTPA and planar V/Q scan are indeterminate.

Electronic supplementary material

The online version of this article (doi:10.1007/s13139-015-0359-8) contains supplementary material, which is available to authorized users.     

Uncommon congenital extracardiac vascular anomalies detected on MSCT (Multi-Slice Computed Tomography) aortic angiography with 64-multislice technology

Objective

The purpose of this study was to evaluate the role of CT angiography in different encountered congenital vascular anomalies of pediatric age groups using 64 multislice CT scanner.

Subjective and methods

Through one year, a total of 15 patients having congenital extracardiac anomalies were encountered from those attending big trauma and emergency center and were studied in this work. Each patient’s parent was thoroughly asked about the detailed clinical history after reviewing the referring imaging request and laboratory findings. Exclusion criteria for CT were as follows: previous allergic reactions to iodine contrast media and severe renal insufficiency. CT examination was performed using 64 multislice CT machine.

Results

CTA examination was performed in a total of 15 patients. The age of the patients was ranging from 2 days to 14 yrs and 5 cases were females. Four cases came with cyanosis; one case came with follow up after operation for transposition of great arteries, while the remaining cases were suffering from medical problems such as respiratory distress or hypertension. Aortic arch hypoplasia, right sided aortic arch with mirror image or with aberrant left subclavian artery, hypoplastic left pulmonary artery with left sided aortic arch and aberrant right subclavian artery, hypoplastic left heart chambers, retrotracheal left pulmonary artery with patent ductus arteriosus (PDA), right superior partial anomalous pulmonary venous drainage (PAPVD) with ASD sinus venosum, postoperative assessment of transposition of great arteries (TGA), fibromuscular dysplasia involving the renal and common iliac arteries, and bilateral double renal arteries with ectopic right kidney were the different extracardiac vascular anomalies encountered in this work.

Conclusion

CTA provides an excellent means to detect a number of extracardiac vascular anomalies and allows accurate and fast noninvasive characterization of extracardiac vascular anatomy. It is a helpful tool in establishing the primary diagnosis, defining anatomic landmarks and relationships, identifying vascular anomalies and helping in postoperative follow-up.     

Simple pulmonary eosinophilia found on follow-up computed tomography of oncologic patients

Objectives

To investigate the prevalence of simple pulmonary eosinophilia (SPE) and validate CT findings of SPE found on follow-up CT of oncologic patients.

Methods

We retrospectively reviewed 6977 cases of oncologic patients who underwent chest CT. A total of 66 individuals who met criteria for having SPE were identified. CT scans were fully re-assessed by consensus of 2 radiologists in terms of characteristics of pulmonary lesions.

Results

The prevalence of SPE was 0.95%. A total of 193 lesions were identified and most of the lesions showed part-solid pattern (69.9%), round to ovoid contour (46.1%), ill-defined margin (90.2%), or partial halo appearance (74.8%). In addition, almost half of the lesions showed the vascular contact (49%). SPE appeared as either solitary (42.4%) or multiple lesions (57.6%). The majority of lesions were located in the periphery (76.2%), and lower lung zonal (67.4%) predominance was found.

Conclusions

The frequency of SPE in oncologic patients with CT findings of GGO, part-solid lesion was high (17.5%). Therefore, when key features of CT findings suggesting SPE (part-solid nodule; ill-defined margin; peripheral distribution; and lower lung zone predominance) are newly discovered on follow-up chest CT in oncologic patients, it would be useful to correlate with blood test and do short-term follow-up in order to avoid unnecessary invasive procedure.     

Multidetector CT chest with bronchial and pulmonary angiography determining causes,site and vascular origin of bleeding in patients with hemoptysis

Objective

To assess the role of MDCT chest with bronchial and pulmonary angiography in determining the cause, site of bleeding, and its vascular origin in patients presenting with hemoptysis.

Materials and methods

Fifty patients suffering from hemoptysis were evaluated by MDCT with bronchial and pulmonary angiographic techniques.

Results

MDCT chest with angiography revealed the cause in 84% of cases, the site and vascular origin in 76% of cases presenting with hemoptysis.

Conclusion

MDCT of the chest with bronchial and pulmonary angiography is considered a primary noninvasive imaging modality in the evaluation of patients with hemoptysis. It also serves as a guide for other diagnostic or therapeutic procedures.