Quantitative and qualitative analysis of in vivo Doppler signal enhancement of FS-069.

RATIONALE AND OBJECTIVES: In vivo lifetime of ultrasound (US) contrast agents is still limited and thus a cause for ongoing investigations of new substances. The purpose of this study was to determine the time intensity changes of the Doppler signals obtained within the femoral vein after two different doses of a new microsphere-based ultrasound contrast agent. METHODS: Twenty-four healthy male volunteers (mean age, 29; average weight, 76 kg) were included in this study. All underwent a triplex Doppler US examination after an intravenous bolus injection of 0.3 mL and 1.0 mL Optison. To examine the signal enhancement characteristics of this contrast agent the audio signal of the pulsed-wave spectral Doppler US was measured quantitatively using an audio analyzer, whereas velocity-encoded color Doppler examinations were scored qualitatively (score 0-3). RESULTS: The mean maximal enhancement of the audio signal at a dose of 1.0 mL FS-069 was significantly higher than with a bolus of 0.3 mL FS-069 (29 +/- 2 dB vs. 26 dB +/- 2 dB, P < 0.001). The time-intensity curves after each bolus injection yielded an early peak (one minute after the injection) followed by constantly decreasing signal intensities. The scoring of the velocity-encoded color Doppler US revealed an optimal enhancement (score 2) for 3 minutes and 20 seconds (0.3 mL Optison) and for 6 minutes (1.0 mL Optison), respectively. CONCLUSIONS: This study showed the capability of triplex Doppler ultrasound signal enhancement after Optison. 1.0 mL Optison proved to be the more appropriate dose for an optimal signal enhancement than 0.3 mL Optison.

Contrast-enhanced helical CT of the head and neck: improved conspicuity of squamous cell carcinoma on delayed scans.

OBJECTIVE: We evaluated the impact of delayed scans on the conspicuity of squamous cell carcinoma in helical CT of the head and neck. SUBJECTS AND METHODS: Twenty-seven patients with biopsy-proven squamous cell carcinoma of the head and neck underwent dual-phase helical CT examinations using 100 mL of nonionic contrast material. In all patients, the early phase started 30 sec after the commencement of injection. The patients were assigned to one of two groups in which the delayed phase started either 180 sec (group A, n = 13) or 300 sec (group B, n = 14) after the start of injection. The overall image quality, including vascular opacification and the quality of lesion conspicuity, was determined according to a three-point scoring system. RESULTS: Overall image quality scored better on the early scans (score, 1.4 +/- 0.5) than on the late scans with a 180-sec (score, 1.6 +/- 0.6; p = 0.03) or a 300-sec delay (score, 2.4 +/- 0.5; p = 0.002). Tumor conspicuity scored better on scans with a 180-sec delay (score, 1.4 +/- 0.5) than on the scans with a 30-sec delay (score, 2.3 +/- 0.7; p = 0.02) or the scans with a 300-sec delay (score, 2.3 +/- 0.7; p = 0.03). In eight (62%) of 13 patients in group A and in six (43%) of 14 patients in group B, the tumor was better delineated on the late scans than on the early scans. CONCLUSION: Although early scans provide optimal vascular enhancement and are therefore necessary for helical CT studies of the head and neck, additional delayed scans may improve lesion detection in patients with squamous cell carcinoma of the head and neck.

Helical CT angiography with maximum intensity projection in the assessment of aortic coarctation after surgery.

OBJECTIVE: The value of CT angiography and three-dimensional (3D) reconstructions was investigated in the postoperative care after surgical repair of aortic coarctation and compared with conventional angiography. SUBJECTS AND METHODS: Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients. RESULTS: The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found. CONCLUSION: CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.

Digital image fusion of CT and PET data sets--clinical value in abdominal/pelvic malignancies.

PURPOSE: We investigated the clinical relevance of digital image fusion of CT and 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography (PET) studies in patients with suspected abdominal and/or pelvic metastasis. METHOD: Nineteen patients with suspected residual/recurrent malignancies underwent CT and [18F]FDG PET studies of the abdomen and/or pelvis. The data sets of both modalities were fused on a digital workstation by automatic adaptation of the pixel size and the slice thickness. Different body positions were corrected by semiautomatic adaptation of the body axes. The fused images were reconstructed in sagittal, coronal, and axial planes. RESULTS: Good spatial correlation between both modalities was achieved in all patients. Image fusion improved the spatial allocation of pathologically increased [18F]FDG uptake in 7 of 35 lesions (20%). CONCLUSION: This work suggests that digital image fusion of CT and [18F]FDG PET data sets improves the anatomical localization of foci with increased [18F]FDG enhancement of the retroperitoneum and the abdominal/pelvic wall, respectively.

Imaging the coronary venous drainage system using electron-beam CT.

This study describes the appearance of the coronary sinus and its tributary veins as visualized on ECG-triggered electron-beam computed tomography (CT) and investigates their spatial relationship to other cardiac structures. Thirty-two patients were examined with ECG-triggered electron-beam CT (exposure time: 100 ms, slice thickness: 1.5 mm) after intravenous contrast agent administration. The entire heart was imaged; the appearance of the coronary sinus and its tributary veins were evaluated. In all 32 patients the anterior interventricular vein and the posterior interventricular vein drained into the coronary sinus. The small cardiac vein was visualized in five patients, a posterior vein of the left ventricle in three and the left marginal vein in eleven. The coronary sinus of all 32 patients had a average length of 30 mm +/- 10 mm (mean +/- SD), range: 21-40 mm and a diameter of 9 mm +/- 5 mm (mean +/- SD), range: 4-14 mm. The results of our work show that if the entire heart volume is scanned using ECG-triggered electron-beam CT, the delineation and the differentiation of the major cardiac veins is possible on transverse cross sections in a way which corresponds to the anatomical literature. Hence to the similar enhancement and similar diameter of coronary veins and arteries on contrast-enhanced electron-beam CT studies, the radiologist should be familiar with the cross-sectional anatomy of the major cardiac veins to prevent possible misinterpretation.

CT number variations due to different image acquisition and reconstruction parameters: a thorax phantom study.

A humanoid thorax phantom containing six compartments was scanned with two different computed tomography (CT) scanners using various image acquisition and reconstruction parameters. The differences of CT numbers were statistically significant between the two CT scanners for each compartment (p<0.001) except for the "air" compartment. The variabilities of the CT numbers are described for the different parameters. The mean CT numbers of the "water" compartment, for instance, ranged from 1 to 15HU (Hounsfield Units), those of the "air" compartment varied from -962 to -990HU. Knowledge of these CT number variabilities is necessary when CT numbers are used for tissue characterization.

Idiopathic sclerotic inflammation of the orbit with left optic nerve compression in a patient with multifocal fibrosclerosis.

We present the MR imaging findings in a 43-year-old male patient with bilateral idiopathic sclerosing inflammation of the orbit. Bilateral enhancing retrobulbar masses, with concentric compression of the retrobulbar segment of the left optic nerve, were seen. MR imaging proved to be the only means to distinguish between the different intraorbital structures and to determine the exact site of optic nerve compression. To our knowledge, this is the first documented case of MR imaging findings of this entity.

Contrast-enhanced spiral CT of the head and neck: comparison of contrast material injection rates.

BACKGROUND AND PURPOSE: Contrast-enhanced spiral CT studies of the head and neck are performed frequently using contrast material volumes of approximately 30 g iodine and a scan delay of 30-45 seconds. Because little is known about the effects of contrast material injection rates on tissue enhancement, this was prospectively investigated in our study. METHODS: Ninety-seven patients underwent spiral CT of the head and neck. Each patient was assigned randomly to one of four groups who received 100 mL of nonionic contrast material (300 mg I/mL) at different monophasic injection flow rates with 1.5, 2, 3, and 4 mL/s. Scanning started after a constant delay of 35 seconds. The attenuation of the carotid artery, jugular vein, and sternocleidomastoid muscle was measured over time and the attenuation of the submandibular and thyroid gland was evaluated. Vascular attenuation of at least 150 HU was considered to be sufficient. RESULTS: The mean scan time was 33+/-5 seconds. The study, using an injection rate of 2 mL/s, showed the longest time of sufficient overall (arterial and venous) vessel attenuation (27+/-4 seconds, P< or =.008). The injection flow rate did not influence significantly muscular attenuation (mean enhancement during scan time: 9+/-7 HU). The 1.5 mL/s protocol showed the lowest attenuation values of the submandibular gland (81+/-12 HU) and the highest attenuation values of the thyroid gland (164+/-22 HU), but the attenuation of the thyroid gland was not statistically different from that revealed by the 2 mL/s protocol. CONCLUSION: Using 100 mL of intravenous contrast material with 300 mg I/mL for spiral CT studies of the entire head and neck, the optimal injection flow is 2 mL/s, whereas lower flow rates resulted in insufficient venous enhancement.

Pericardial sinuses and recesses: findings at electrocardiographically triggered electron-beam CT.

PURPOSE: To evaluate the appearance of the pericardial sinuses and recesses at electrocardiographically triggered electron-beam computed tomography (CT). MATERIALS AND METHODS: Findings in 100 patients without known pericardial disease were reviewed. The patients underwent electron-beam CT of the heart because of suspected coronary arterial disease. Incremental electrocardiographically triggered images were obtained with a 100-msec exposure time and 1.5-mm section thickness after intravenous administration of contrast material. The appearance of the pericardial sinuses and recesses was determined. RESULTS: In each patient, at least one of the sinuses was visible at CT. The transverse and oblique sinuses (or one of their recesses) were depicted in 95 and 89 patients, respectively. The left pulmonic recess was depicted in 81 patients; inferior aortic recess, 80 patients; posterior pericardial recess, 67 patients; left pulmonic vein recess, 60 patients; right pulmonic recess, 51 patients; superior aortic recess, 47 patients; right pulmonic vein recess, 29 patients; and postcaval recess, 23 patients. CONCLUSION: Pericardial sinuses and recesses are frequently depicted on electrocardiographically triggered electron-beam CT images. Knowledge of their locations is helpful in the differentiation of normal pericardium from pericardial effusions and mediastinal processes such as lymph nodes.

Anterior and upward displacement of the inferior mesenteric vein:a new diagnostic clue to left paraduodenal hernias?

A 26-year-old man with acute deterioration of recurrent abdominal pain was admitted to the hospital. Plain film (abdominal radiographs), spiral computed tomography (CT), and barium contrast studies were performed. A left paraduodenal hernia causing acute jejunal obstruction was identified on upper gastrointestinal barium studies and spiral CT. Pre- and postsurgery examinations were compared, and relevant radiological findings were identified. Spiral CT provided excellent visualization of the pathognomonic displacement of the inferior mesenteric vein.

Morphometric measurement of abdominal organs. Comparison of ultrasound and spiral CT.

PURPOSE: To determine interobserver variability in the morphometric measurement of abdominal organs with US and spiral CT, and to compare the results obtained with these two modalities. MATERIAL AND METHODS: US and spiral CT examinations of the abdomen were performed in 25 patients. In each patient, 13 defined distances were measured in the liver, spleen and both kidneys with US and spiral CT by two pairs of radiologists in a blinded manner. The interobserver variations of these measurements were evaluated for the US and CT examinations, and the data of both modalities were compared with one another. RESULTS: The measurement of distances in the abdomen with US and spiral CT is subject to considerable interobserver variability in both modalities. The relative interobserver variations showed marked differences, according to which distance was measured. The average interobserver variations were higher in US than in CT. A direct comparison of US and spiral CT revealed that distances obtained with CT frequently exceeded those obtained with US. CONCLUSION: Morphometric measurements of abdominal organs with US and with spiral CT showed considerable differences. The follow-up examinations should therefore be performed with the same imaging modality as used in the original examination.

The peripheral intravenous cannula: a cause of venous air embolism.

Venous air embolism has been reported as a complication of invasive diagnostic and therapeutic procedures or accidental trauma. Little is known about the incidence of air embolism after minimal intravenous manipulations, such as the insertion of a peripheral intravenous cannula. Small air emboli in the central veins, central arteries, and cardiac chambers can be detected during electron-beam computed tomography studies of the chest. Electron-beam computed tomography of the chest was performed on 208 patients after the insertion of a peripheral intravenous cannula. The images were analyzed using a digital workstation. Small air embolism was visible in 10 of 208 (4.8%) patients in the following locations: the pulmonary trunk in 6 patients, the right ventricle in 2, the right atrium in 1, and the left brachiocephalic vein in 1. The embolism was asymptomatic in each patient. Although the potential risks in patients with septal defects and shunts remain unclear, caution should be taken with minimal intravenous manipulations.

Vascular air embolism: location, frequency, and cause on electron-beam CT studies of the chest.

PURPOSE: To determine the frequency and location of venous air emboli that occur with the use of electron-beam computed tomographic (CT) studies of the chest. MATERIALS AND METHODS: Findings from 677 patients who underwent chest electron-beam CT with intravenous administration of contrast material were reviewed. Unenhanced CT studies were performed in 127 (18.8%) of these patients while the intravenous cannula was in place but before injection of contrast material. RESULTS: Air emboli were observed on CT studies in 79 (11.7%) of 677 patients. Emboli were small (up to three air bubbles less than 1 cm in diameter) in 70 (10.3%) patients and were moderate (more than three air bubbles or bubbles 1-2 cm in diameter) in nine (1.3%) patients. Air emboli were located in the main pulmonary artery (n = 54 [8.0%]), superior vena cava (n = 12 [1.8%]), right ventricle (n = 10 [1.5%]), subclavian or brachiocephalic vein (n = 6 [0.9%]), and right atrium (n = 5 [0.7%]). Seven patients (1.0%) had emboli in more than one location. Air emboli were depicted on unenhanced CT scans of seven (5.5%) of 127 patients. No association was found between the frequency of air embolism and injection flow, injection site, or amount or type of contrast agent. CONCLUSION: Intravenous administration of contrast material may cause small to moderate-sized air emboli. Knowledge of the common locations of emboli can help radiologists distinguish them from image artifacts or paravasal air collections.

CT-anatomy of the nasolacrimal sac and duct.

Recent developments in ophthalmology such as balloon dilatation, stent implantation, laser therapy and endoscopy of the lacrimal drainage system raise the need for a detailed anatomical knowledge of this system. In this study morphometric measurements of the lacrimal drainage system were performed with thin-section axial computed tomography (CT) examinations in 147 patients with no signs of pathology related to the lacrimal drainage system. The mean length of the nasolacrimal duct measured 11.2 +/- 2.6 mm (range: 6-21 mm), the narrowest diameter was 3.7 +/- 0.7 mm (range: 2-7 mm). The mean length of the nasolacrimal sac was 11.8 +/- 2.5 mm (range: 6-18 mm). The width of the nasolacrimal sac did not exceed 4 mm unless filled with air. In 43 (29.3%) of the subjects air was visible within the nasolacrimal sac or duct. The knowledge of the morphometry of the lacrimal drainage system enables the ophthalmologist to plan intervention on the lacrimal drainage system precisely and avoid unnecessary manipulations.