Thromboembolic disease detection at indirect CT venography versus CT pulmonary angiography

PURPOSE: To assess the incremental increase in thromboembolic disease detection at indirect computed tomographic (CT) venography versus CT pulmonary angiography and to determine the importance of scan interval for indirect CT venography on the basis of thrombus length. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was not required. The study included 1590 consecutive patients undergoing CT pulmonary angiography for the suspicion of pulmonary embolism. Two minutes after completion of pulmonary angiography, a contiguous indirect CT venography was performed from the iliac crest to the popliteal fossa. The presence of pulmonary embolism or deep venous thrombosis (DVT) was recorded for all patients. The lengths of all deep venous thrombi found in the first 378 consecutive patients were recorded. RESULTS: Pulmonary embolism was detected in 243 (15%) of 1590 patients at CT pulmonary angiography, and DVT was detected in 148 (9%) patients at indirect CT venography. Among 148 patients with DVT, pulmonary embolism was detected in 100 patients at CT pulmonary angiography. Thus, the addition of indirect CT venography to CT pulmonary angiography resulted in a 20% incremental increase in thromboembolic disease detection compared with that at CT pulmonary angiography alone (99% confidence interval: 17%, 23%). Among the 378 patients, DVT was present in 33 patients at indirect CT venography. Two (6%) of 33 patients had clots measuring 2 cm or less, six (18%) had clots measuring 3-4 cm, and 25 (76%) had clots measuring more than 4 cm in length. CONCLUSION: The addition of indirect CT venography to CT pulmonary angiography incrementally increases the detection rate of thromboembolic disease by 20%. Performance of indirect CT venography by using contiguous section intervals, with a section width of 1 cm, is recommended to accurately detect DVT.     

Thromboembolic disease: comparison of combined CT pulmonary angiography and venography with bilateral leg sonography in 70 patients

OBJECTIVE. The purpose of this study was to compare combined CT pulmonary angiography and venography with leg sonography for accuracy and relative efficacy in diagnosis of deep venous thrombosis from the popliteal vein to the common femoral vein. SUBJECTS AND METHODS. Seventy consecutive patients with clinically suspected pulmonary embolism underwent both combined CT pulmonary angiography and venography and bilateral leg sonography within 24 hr. CT venograms were analyzed independently in a blinded fashion for quality of venous opacification and patency by two observers. CT venography was compared with sonography for femoropopliteal vein thrombosis, and the final assessment based on multiple subjective and objective clinical and imaging criteria was recorded in three categories: 1, CT venography better than sonography; 2, CT venography equivalent to sonography; and 3, sonography better than CT venography. RESULTS. Sixty-eight patients (97%) had a satisfactory or good quality CT venography examination. Two CT venography studies had false-positive findings due to flow artifacts. Both CT venography and sonography had positive findings for deep venous thrombosis in five patients, and both had negative findings in 63 patients (100% sensitivity, 97% specificity, 100% negative predictive value, and 71% positive predictive value). CT venography was better and more efficacious than sonography (category 1) in 25 patients (36%). CT venography was equivalent to sonography (category 2) in 26 patients (37%), and sonography was better than CT venography (category 3) in 19 patients (27%). CONCLUSION. Compared with sonography, CT venography in addition to CT pulmonary angiography is a relatively accurate method for evaluation of femoropopliteal venous thrombosis. Combined CT pulmonary angiography and CT venography may be more efficacious than sonography or two separate examinations in selected patients.     

CT pulmonary angiography for the detection of pulmonary embolism: interobserver agreement between on-call radiology residents and specialists (CTPA interobserver agreement)

PURPOSE: The aim of this study was to prospectively determine interobserver agreement between on-call radiology residents and specialists in the interpretation of computed tomographic pulmonary angiography (CTPA). METHODS: CTPA examinations obtained between January 2002 and March 2003 were interpreted by a radiology resident on call and by two radiology specialists. Agreement was assessed using percentage of agreement between interpreters and by the kappa coefficient. Sensitivity of residents' interpretations was calculated by relating them to the interpretation of Specialist 1, which served as the gold standard. RESULTS: Of the 81 CTPA examinations evaluated, there was agreement of 93% and 91% for the diagnosis of pulmonary embolism (PE) and of 97% and 85% for the exclusion of PE with Specialist 1 and 2, respectively. The concordance between residents' interpretations and those of Specialist 1 was very high (kappa=.8), and with those of Specialist 2 was high (kappa=.7). In all cases of agreement between the two specialists, there was complete agreement between the specialists' and the residents' intepretations. CONCLUSIONS: Our study showed good to very good agreement of residents' interpretations with each of the radiology specialists. Therefore, relying on the residents' preliminary interpretations during after-hour calls is reasonable.     

Assessment of intra- and interobserver variability of pulmonary vein measurements from CT angiography

RATIONALE AND OBJECTIVES: Pulmonary vein (PV) stenosis is a common complication after radiofrequency ablation for atrial fibrillation. This study investigated the intra- and interobserver variability and precision of PV ostial measurements from three-dimensional computed tomography angiography. MATERIALS AND METHODS: Four observers measured the maximum and minimum diameters, as well as area, of the four PVs of seven patients who underwent a three-dimensional computed tomography scan before radiofrequency ablation. Each observer performed two sets of measurements. The intra- and interobserver variability of the measurements was calculated using analysis of variance. RESULTS: Intraobserver variability was approximately two times lower than interobserver variability in measurements of diameter and area. The standard error of the measurement (SEM), SEM(intra) and SEM(inter), were lower for the mean diameter than the maximum diameter. The minimum detectable changes in diameters, DeltaD(intra) and DeltaD(inter), and area, DeltaA(intra) and DeltaA(inter), demonstrated the same statistical trend as the corresponding SEM for each of the four veins. Both DeltaD(intra) and DeltaD(inter) and DeltaA(intra) and DeltaA(inter) were smaller than the corresponding lower bounds of the 95% confidence interval for 50% diameter reduction and 75% area reduction. The direct results of DeltaA(intra) and DeltaA(inter) for each of the four veins were consistently less than DeltaA's calculated from the corresponding DeltaD(intra) and DeltaD(inter). CONCLUSION: PV ostial measurements are less variable when made by a single observer than by multiple observers, and mean diameter measurements are more precise than a single, maximum diameter measurement. Both diameter and area measurements are capable of quantifying the mild PV stenosis. Furthermore, area can be measured with greater precision than mean diameter and should be used in PV ostium caliber determination.     

Optimization of combined CT pulmonary angiography with lower extremity CT venography

OBJECTIVE: We wanted to determine the time delay for maximum enhancement of the deep venous system of the lower extremities after standard CT pulmonary angiography. SUBJECTS AND METHODS: In 20 patients who had undergone standard CT pulmonary angiography, we measured arterial and venous enhancement at the level of the greater trochanter. These measurements were obtained at 30-sec intervals immediately after completion of CT pulmonary angiography. Ten measurements were obtained in 5 min. Time-density curves were plotted. RESULTS: We found that the median and average peak venous enhancements were 92 and 95 H, respectively. Time to peak enhancement was variable. Because of the broad shape of the venous time-density curve, near peak enhancement could be achieved in most patients at 2 min after CT pulmonary angiography. CONCLUSION: CT of the deep venous system of the lower extremities after standard CT pulmonary angiography, performed with appropriate timing considerations, allows near maximal enhancement of the venous system in most patients without altering the optimum CT pulmonary angiography protocol.     

Deep venous thrombosis with suspected pulmonary embolism: detection with combined CT venography and pulmonary angiography

PURPOSE: To determine the frequency and location of deep venous thrombosis at computed tomographic (CT) venography after CT pulmonary angiography in a large series of patients clinically suspected of having pulmonary embolism and to compare the accuracy of CT venography with lower-extremity venous sonography. MATERIALS AND METHODS: Venous phase images were acquired from the diaphragm to the upper calves after completion of CT pulmonary angiography in 650 patients (373 women, 277 men; age range, 18-99 years; mean age, 63 years) to determine the presence and location of deep venous thrombosis. Results of CT venography were compared with those of bilateral lower-extremity venous sonography in 308 patients. RESULTS: A total of 116 patients had pulmonary embolism and/or deep venous thrombosis, including 27 patients with pulmonary embolism alone, 31 patients with deep venous thrombosis alone, and 58 patients with both. Among 89 patients with deep venous thrombosis, thrombosis was bilateral in 26, involved the abdominal or pelvic veins in 11, and was isolated to the abdominal or pelvic veins in four. In patients in whom sonographic correlation was available, CT venography had a sensitivity of 97% and a specificity of 100% for femoropopliteal deep venous thrombosis. CONCLUSION: Combined CT venography and pulmonary angiography can accurately depict the femoropopliteal deep veins, permitting concurrent testing for venous thrombosis and pulmonary embolism. CT venography also defines pelvic or abdominal thrombus, which was seen in 17% of patients with deep venous thrombosis.     

Comparison of on-call radiology resident and faculty interpretation of 4- and 16-row multidetector CT pulmonary angiography with indirect CT venography

RATIONALE AND OBJECTIVES: On-call radiology residents frequently interpret computed tomography (CT) pulmonary angiography and CT venography studies outside of routine working hours. The purpose of this study was to compare resident and faculty interpretation concordance rates and to see if concordance rates differed depending on the number of CT detectors used. MATERIALS AND METHODS: The study population included 122 consecutive CT pulmonary angiography (CTPA) and CT venography (CTV) examinations performed on a four-row multidetector CT (MDCT) and 125 consecutive CTPA examinations performed using a 16-row MDCT scanner with CTV performed in 124 patients. Preliminary resident reports and final faculty reports were compared. Discrepant cases were independently reviewed by three cardiothoracic radiologists who were unaware of the initial interpretations. Interpretation concordance rates were calculated for both 4- and 16- row MDCT studies and compared using Fisher's exact test. RESULTS: Resident and faculty CTPA and CTV interpretations were concordant in 80% of the 4-row cases and 94% of the 16-row cases. When comparing resident interpretation to the final expert reference standard, the corrected resident error rate was 11% and 2% for 4-row CTPA and CTV, respectively and 4% and 2% for 16-row CTPA and CTV, respectively. Overall CTPA and CTV concordance was significantly lower for 4-row MDCT (80% versus 94%, P < .001 [two-sided] by Fisher's exact test). CONCLUSIONS: Radiology resident interpretation of CTPA and CTV studies demonstrates a high level of agreement with radiology faculty interpretation. Concordance rates are significantly higher for 16-row MDCT than 4-row MDCT which may be due to improved image quality.     

Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography

PURPOSE: To retrospectively evaluate small-bowel enhancement characteristics and the sensitivity, specificity, and interobserver agreement of computed tomographic (CT) findings by using histologic and endoscopic results as a reference standard in patients undergoing enteric phase CT enterography. MATERIALS AND METhods: The institutional review board approved this retrospective HIPAA-compliant study, which included patients who consented to having their medical records used for research purposes. Enteric phase CT enterographic and ileoscopic findings with or without ileal histologic results were examined in 42 patients (24 women, 18 men). Enteric phase CT enterography was performed after 150 mL of intravenous contrast material was administered at 4 mL/sec, with a 45-second delay. Mural attenuation was measured in the distended and collapsed jejunal and ileal loops and in the terminal ileum. Two radiologists examined CT images for findings of Crohn disease. Mural attenuation for different bowel loops was compared by using a Student t test, with kappa statistics used to measure interobserver agreement and Pearson correleation coefficients used to compare visual and quantitative measures. RESULTS: Distended jejunal loops had significantly greater attenuation than distended ileal loops (113 HU vs 72 HU; P < .001). Attenuation of collapsed jejunal (134 HU) and ileal (108 HU) loops was greater than that of distended jejunal and ileal loops (P < .001). Terminal ileal enhancement was the most sensitive visual CT finding of Crohn disease for both radiologists. Mural thickening demonstrated the greatest interobserver agreement (kappa = 0.83). Visual enhancement and quantitative mural attenuation were significantly correlated (P < .003). CONCLUSION: At enteric phase CT enterography, jejunal attenuation is greater than ileal attenuation and collapsed bowel loops demonstrate greater attenuation than distended bowel loops. Mural hyperenhancement and increased mural thickness are the most sensitive CT findings of active Crohn disease.     

螺旋 CT在肺动脉及下肢静脉联合检查中的成像方法

目的 探讨造影剂双期注射方法在多层螺旋CT肺动脉造影联合下肢静脉造影(CTVPA)中的技术应用.方法 应用多层螺旋CT对30例疑似肺动脉栓塞的病人进行肺动脉造影(CTPA)联合下肢深静脉造影(CTV).A组(15例)采用120~150 mL对比剂,注射速率4 mL/s.B组(15例)采用120~150 mL对比剂,双期注射,第一期50 mL,注射速率4 mL/s,第二期注射70~110 mL对比剂,注射速率2 mL/s,为对照组(B组).对肺动脉各级血管CT均值和下肢静脉血管CT均值进行测量及上腔静脉伪影进行评价.结果 30例检查中肺动脉各级血管和下肢静脉均得到良好的强化,2组无显著性差异.上腔静脉伪影评价,B组上腔静脉伪影对右肺动脉及右上叶动脉的影响明显少于A组,存在显著性差异(P＜0.05).结论 应用双期对比剂注射方法可以得到良好的肺动脉各级血管和下肢深静脉的强化,并可降低上腔静脉伪影的影响,可作为CTVPA的有效检查方法.     

Computed tomography pulmonary angiography with pelvic venography in the evaluation of thrombo-embolic disease

A prospective study was performed to evaluate the usefulness of CT pelvic venography (CTV) in the detection of pelvic vein thrombosis in patients referred for CT pulmonary angiography (CTPA) for suspected pulmonary embolism. Fifty consecutive patients referred for CTPA had CTV performed at the time of CTPA. All patients had duplex ultrasound (DUS) of the lower limb veins for evaluation of deep venous thrombosis (DVT) within 24 h of the CT study. Twelve (24%) of the 50 patients had pulmonary embolism diagnosed on CTPA. Associated DVT was detected in six of these patients; two cases were detected by CTV alone, while one case was detected by both CTV and DUS. The remaining three cases had DVT diagnosed by DUS alone. In the 38 patients with a negative CTPA, three patients had venous thrombus diagnosed by CTV. Of these three patients, two had a negative DUS study. CTV therefore led to a definitive imaging diagnosis of thrombo-embolic disease in two (4%) more patients. CTV adds little time and cost to the CTPA examination and leads to a moderate increase in definite imaging diagnosis of thrombo-embolic disease.     

Intraobserver and interobserver variability in CT angiography and MR angiography measurements of the size of cerebral aneurysms

Purpose

Accurate and reliable measurement of aneurysm size is important for treatment planning. The purpose of this study was to determine intraobserver and interobserver variability of CTA and MRA for measurement of the size of cerebral aneurysms.

Methods

Thirty patients with 33 unruptured cerebral aneurysms (saccular, >3 mm in their maximal dimension, with no daughter sacs or lobulations) who underwent 256-row multislice CTA, 3-D TOF MRA at 3.0T, and 3D rotational angiography (3DRA) were retrospectively analyzed. Three independent observers measured the neck, height, and width of the aneurysms using the CTA and MRA images. Intraobserver and interobserver variability of CTA and MRA measurements was evaluated using the standardized difference and intraclass correlation coefficient, with 3DRA measurements as the reference standard. In addition, the mean values of the measurements using CTA and MRA were compared with those using 3DRA.

Results

The overall intraobserver and interobserver standardized differences in CTA/MRA were 12.83–15.92%/13.48–17.45% and 14.08–17.00%/12.08–17.67%, respectively. The overall intraobserver and interobserver intraclass correlation coefficients of CTA/MRA were 0.88–0.98/0.84–0.96 and 0.86–0.98/0.85–0.95, respectively. Compared to the height and width measurements, measurements of the neck dimensions showed higher intraobserver and interobserver variability. The sizes of the cerebral aneurysms measured by CTA and MRA were 1.13–9.26 and 5.20–9.67% larger than those measured by 3DRA, respectively; however, these differences were not statistically significant.

Conclusion

There were no noticeable differences between intraobserver and interobserver variability for both CTA- and MRA-based measurements of the size of cerebral aneurysms.

     

Multidetector row CT angiography of the abdominal aorta and lower extremities in patients with peripheral arterial occlusive disease: diagnostic accuracy and interobserver agreement

Purpose: To evaluate the accuracy of four channel multidetector row CT angiography (MDCTA) of the abdominal aorta and lower extremities arteries compared with digital subtraction angiography (DSA). Materials and methods: In our prospective study 42 patients with peripheral vascular occlusive disease (27 M, 15 F, age range 40–79 years) underwent MDCTA and DSA within 5 days. Images were blindly interpreted by two radiologists. Maximum intensity projections (MIP), multiplanar (MPR) reformations, three-dimensional (3D) reconstructions as well as axial images were available for analysis of MDCTA. DSA were analyzed on hard copies. Results: Overall sensitivity and specificity of MDCTA were 93 and 95%, respectively, with positive and negative predictive values of 90 and 97%. Overall diagnostic accuracy was 94%. Normal arterial segments and 100% occlusions were correctly identified in all cases by MDCTA. Moderately stenotic segments interpretation in the calves appeared to be more controversial, but no statistical difference in accuracy of MDCTA in the infrapopliteal district arteries was noted with respect to accuracy in the more proximal arterial bed. Good to excellent interobserver and intraobserver agreement were observed, with k values greater than 0.80. Conclusions: MDCTA of the abdominal aorta and lower extremities is an accurate imaging modality in clinical practice when compared with DSA.     

Combined CT venography and pulmonary angiography in suspected thromboembolic disease: diagnostic accuracy for deep venous evaluation

OBJECTIVE: Combined CT venography and pulmonary angiography is a new diagnostic test that evaluates both pulmonary embolism and deep venous thrombosis (DVT) in a single study. Our purpose was to compare the CT venous findings with lower extremity venous sonography. SUBJECTS AND METHODS: Seventy-one consecutive patients with suspected pulmonary embolism underwent helical CT pulmonary angiography during rapid i.v. infusion of contrast medium. Axial scans at 5-cm intervals from the patient's upper calves to the diaphragm were generated 3.5 min after the beginning of contrast medium injection. CT venous phase images were interpreted prospectively and compared with subsequent bilateral lower extremity venous sonography performed within 12 hr. RESULTS: DVT was revealed by CT venous phase images in 19 patients, 12 of whom also had pulmonary embolism. CT and sonographic findings correlated exactly in the femoropopliteal deep venous system, where most pulmonary emboli originate. CT venous phase images also revealed pelvic extension of DVT in six patients and isolated vena cava thrombus in one patient. CONCLUSION: CT venous phase imaging at the time of CT pulmonary angiography is comparable with venous sonography in the evaluation of femoropopliteal DVT. The iliac veins and vena cava, vessels poorly shown on sonography but sometimes the source of significant pulmonary emboli, are also depicted by CT venography.     

Display method can affect interobserver agreement: comparison of 'zoom-and-pan' and 'browse-and-paste' for primary CT interpretation.

Eight radiologists interpreted body CT images of 30 cases using a viewing station (six 17-in. monitors, 1024x1280). Using two different display methods, 'zoom-and-pan' and 'browse-and-paste', the readers described the presence or absence of liver tumors using a five-point rating scale and temporal changes between the current and previous studies using a seven-point rating scale. There was no significant difference in kappa values for tumor detection between the two display modes. However, in describing temporal changes, the kappa value of the browse-and-paste was significantly lower than that of zoom-and-pan (p<0.01). Browse-and-paste may have the disadvantage of greater interobserver variation.