A retrospective observational study investigating the factors associated with right heart failure in patients with primary acute pulmonary embolism and deep vein thrombosis.

BACKGROUND: The relationship between the risk of right heart failure in primary acute pulmonary embolism after embolization and the residual thrombus sites in the pelvis and lower limbs is not clear. METHODS: This single-center retrospective observational study examined the results of contrast-enhanced computed tomography and venous ultrasonography of patients with primary acute PE and DVT. We assessed the association between the occurrence of right heart failure and age; gender; pulmonary thrombosis distribution; most proximal site of deep vein thrombosis in the soleal vein, inferior vena cava (IVC), or common iliac vein (CIV); DVT distribution; and malignancy using univariate and multivariate logistic regression. RESULTS: In all, 77 of 165 patients were male (mean age: 65.1 ± 13.7 years). Right heart failure occurred in 53 patients (32.1%). Multivariate analysis revealed that the odds ratio (OR) for right heart failure was significantly lower in patients with the most proximal site of DVT in the IVC/CIV (OR = 0.07, 95% confidence interval [CI] 0.01-0.62, P = .017), while it was significantly higher in females (OR = 2.51, 95% CI 1.05-6.01, P = .039), and in patients who exhibited the presence of bilateral venous thrombosis (OR = 3.89, 95% CI 1.60-9.48, P = .003). CONCLUSION: A significant factor involved in PE without right heart failure was the most proximal site of DVT in the IVC/CIV, and significant risk factors associated with PE with right heart failure were more prevalent in females and in patients who exhibited the presence of bilateral venous thrombosis.

Evaluation of the Effect of Tumor Position on Standardized Uptake Value Using Time-of-Flight Reconstruction and Point Spread Function.

OBJECTIVES: The present study was conducted to examine whether the standardized uptake value (SUV) may be affected by the spatial position of a lesion in the radial direction on positron emission tomography (PET) images, obtained via two methods based on time-of-flight (TOF) reconstruction and point spread function (PSF). METHODS: A cylinder phantom with the sphere (30 mm diameter), located in the center was used in this study. Fluorine-18 fluorodeoxyglucose (18F-FDG) concentrations of 5.3 kBq/ml and 21.2 kBq/ml were used for the background in the cylinder phantom and the central sphere respectively. By the use of TOF and PSF, SUV max and SUV mean were determined while moving the phantom in a horizontal direction (X direction) from the center of field of view (FOV: 0 mm) at 50, 100, 150 and 200 mm positions, respectively. Furthermore, we examined 41 patients (23 male, 18 female, mean age: 68±11.2 years) with lymph node tumors, who had undergone 18F-FDG PET examinations. The distance of each lymph node from FOV center was measured, based on the clinical images. RESULTS: As the distance of a lesion from the FOV center exceeded 100 mm, the value of SUV max , which was obtained with the cylinder phantom, was overestimated, while SUV mean by TOF and/or PSF was underestimated. Based on the clinical examinations, the average volume of interest was 8.5 cm3. Concomitant use of PSF increased SUV max and SUV mean by 27.9% and 2.8%, respectively. However, size of VOI and distance from the FOV center did not affect SUV max or SUV mean in clinical examinations. CONCLUSION: The reliability of SUV quantification by TOF and/or PSF decreased, when the tumor was located at a 100 mm distance (or farther) from the center of FOV. In clinical examinations, if the lymph node was located within 100 mm distance from the center of FOV, SUV remained stable within a constantly increasing range by use of both TOF and PSF. We conclude that, use of both TOF and PSF may be helpful.

Noninvasive visualization of endoleaks after endovascular aortic aneurysm repair through unenhanced MRI with motion-sensitized driven equilibrium preparation: Phantom experiments.

PURPOSE: To optimize imaging parameters for balanced turbo field echo (BTFE) sequence combined with motion-sensitized driven equilibrium (MSDE) preparation for endoleak detection and type classification in phantom experiments. MATERIALS AND METHODS: We prepared four phantoms: a pulsatile flow generator with an aortic aneurysm model simulating no endoleak, and a type-1, type-2, and type-3 endoleak. Throughout the experiments, MSDE-BTFE images with and without flow suppression were obtained at 1.5 T and subtraction images were used for image evaluation. The no-endoleak phantom was imaged using different MSDE-BTFE sequences to optimize the k-space trajectory and evaluate the use of electrocardiogram gating. The relative contrast between flowing saline and background was calculated. Then all phantoms were imaged to determine the optimal velocity encoding (VENC) for endoleak detection and type classification. Three independent observers performed the image evaluation. Consistencies between the interpreted and true results were analyzed using kappa statistics. RESULTS: The 3D low-high k-space trajectory with electrocardiogram gating provided the highest relative contrast. Low VENCs of 2-10 cm/s and high VENCs of 20 cm/s showed perfect consistency in endoleaks detection and type classification, respectively. CONCLUSION: MSDE-BTFE sequences of appropriate VENCs has potential for endoleak detection and type classification, without contrast material.

[Applicability of PROSET-MRA for evaluating pediatric moyamoya disease].

MR angiography (MRA) for pediatric moyamoya disease is important as a non-invasive examination to diagnose blood flow in the brain. Generally, the conventional 3D-TOF MRA is used for moyamoya disease. However, retrobulbar and subcutaneous fat of the head show high intensity signals. We found that using the conventional MRA to diagnose the details of brain blood flow is difficult and that it cannot differentiate moyamoya vessels and fat. It similarly obscures the ophthalmic artery and superficial temporal artery that overlap with fat in the direction of the maximum intensity projection (MIP). Therefore, we devised an MRA technique with fat suppression to diagnose blood flow in moyamoya disease patients: MR angiography with the principle of selective excitation technique (PROSET). The scan time does not need to be increased. We studied the TOF effect in constant and pulsatile flows and the water selective excitation method with the binominal pulse (PROSET) for the fat suppression effect for moyamoya disease. The results showed that PROSET-MRA achieved better image results than conventional MRA. The development of collaterals of the superficial temporal artery and occipital artery in pre- and post-operation moyamoya disease could be clearly visualized and evaluated. The PROSET-MRA method is useful for evaluating pre- and post-operation (encephalo-duro-arterio-synangiosis, encephalo-myo-synangiosis) blood flow reconstruction for patients who have moyamoya disease.

[Usefulness of the adaptive dose shield for the infant CT].

The spiral scan with a wide detector row such as the 64-detector row computed tomography (CT) system may increase radiation exposure for infants because the irradiation range is wider than the planned range. The adaptive dose shield (ADS) prevents radiation exposure greater than the planned range. We examined the usefulness of the protection effect of the ADS for the infant inner ear CT. To confirm the protection effect of the ADS, we scanned X-ray films by using the 64-detector row CT system and measured the difference of the planned range and the irradiation range. The result of that is that when the planned range was small, the protection effect for the scan ending side was inferior to the scan starting side. And also, when the gantry rotation speed and pitch factor (PF) were high values, the protection effect was inferior to a low gantry rotation speed and low PF. There was a combination of gantry rotation speed and PF at which the protection effect decreases. Due to changes of the scanning direction and PF for the infant inner ear, the crystalline lens radiation exposure dose decreased from 11.89 mGy to 4.37 mGy. In conclusion, the ADS can reduce the radiation exposure dose of an adjacent organ. Therefore, it was thought that the ADS was a useful radiation exposure reduction function for infants in the 64-detector row CT system.

[A study of the influence scan timing and depiction of blood vessel diameter in CE-3DMRA: simulation by pulsatile flow].

In imaging using contrast-enhanced three-dimensional magnetic resonance angiography (CE-3DMRA), optimizing the delay time from the start of intravenous injection of contrast medium to the start of scanning has generally been an important concern when obtaining blood vessel images of good contrast. Recent methods of mechanically assessing the attainment of contrast medium injection include Smart-Prep and others. Another method is the Test Bolus, in which a small amount of contrast medium determines the timing of scan start, in quest of the time intensity curve. Because these methods are not necessarily satisfactory, the corrected method is used in clinical cases. In terms of how scan timing affects blood vessel depiction, no study has examined pulsatile flow, which is carried out by simulation. On the other hand, there are reports on data filling of k-space using imitation blood vessels on a computer and simple experimental equipment. This research examined experimentally blood vessel depiction according to scan timing and the diameter of blood vessels by using a systemic circulation simulator that incorporated hemodynamic circulation in which pulsatile flow is the same as that of a human body, using an artificial heart developed especially for MRI. It is thought that scan timing in CE-3DMRA affects the depiction of blood vessels for which the diameter of the blood vessel differs from the experimental result. Phase-encoding k-space data filling is the contrast-to-noise ratio (CNR) of each blood vessel irrespective of sequential and centric k-space ordering. The timing shift phenomenon, in which a blood vessel is so thin that the scan timing is overdue and shows a relatively high value, can occur. Moreover, that scan timing affects not only the diameter of a blood vessel but also depiction of the narrowing of a stenotic blood vessel or a branch blood vessel was demonstrated clinically and experimentally. Therefore, blood vessel depiction changes with scan timing, and it is clinically important to determine the time of arrival of contrast medium and the duration of the enhancement effect in quest of the time intensity curve by test bolus when clearly describing the target blood vessel.