[Show abstract][Hide abstract] ABSTRACT: To describe an unusual enhancement pattern of hepatosplenic candidiasis (HSC) liver lesions in biphasic spiral liver computed tomography (CT).
Twenty-one patients with suspected HSC were scanned with a biphasic liver CT perfusion protocol. The liver lesions detected were assessed for their morphology and enhancement pattern during both perfusion phases. A liver biopsy was performed in 11/21 patients.
The majority of hepatic lesions in 15/21 patients showed the well-known abscess-like pattern. In 6/21 patients an uncommon central contrast enhancement with a peripheral double ring was detected in the arterial phase. In some cases the lesions showed decreased diameter or even seemed to disappear completely in the portalvenous phase.
CT in the arterial phase showed an unusual enhancement pattern of liver lesions in HSC. Scanning only in the portalvenous phase implies possible pitfalls, because lesions may be overlooked or undersized. Therefore, biphasic liver CT is considered essential in the diagnosis and follow-up of HSC in clinical practice.
[Show abstract][Hide abstract] ABSTRACT: Our objective was to compare a single-slice CT (SS-CT) scanner with a multi-slice CT (MS-CT) scanner in the depiction of osseous anatomic structures and fractures of the upper cervical spine. Two cervical spine specimens with artificial trauma were scanned with a SS-CT scanner (HighSpeed, CT/i, GE, Milwaukee, Wis.) by using various collimations (1, 3, 5 mm) and pitch factors (1, 1.5, 2, 3) and a four-slice helical CT scanner (LightSpeed, QX/i, GE, Milwaukee, Wis.) by using various table speeds ranging from 3.75 to 15 mm/rotation for a pitch of 0.75 and from 7.5 to 30 mm/rotation for a pitch of 1.5. Images were reconstructed with an interval of 1 mm. Sagittal and coronal multiplanar reconstructions of the primary and reconstructed data set were performed. For MS-CT a tube current resulting in equivalent image noise as with SS-CT was used. All images were judged by two observers using a 4-point scale. The best image quality for SS-CT was achieved with the smallest slice thickness (1 mm) and a pitch smaller than 2 resulting in a table speed of up to 2 mm per gantry rotation (4 points). A reduction of the slice thickness rather than of the table speed proved to be beneficial at MS-CT. Therefore, the optimal scan protocol in MS-CT included a slice thickness of 1.25 mm with a table speed of 7.5 mm/360 degrees using a pitch of 1.5 (4 points), resulting in a faster scan time than when a pitch of 0.75 (4 points) was used. This study indicates that MS-CT could provide equivalent image quality at approximately four times the volume coverage speed of SS-CT.
No preview · Article · Sep 2002 · European Radiology
[Show abstract][Hide abstract] ABSTRACT: To determine the incidence of acute pulmonary emboli extending across the bifurcation of the main pulmonary artery, lobar arteries or segmental arteries (interpulmonary, interlobar or intersegmental saddle emboli, respectively).
128 patients with clinically suspected acute pulmonary embolism underwent electron beam tomography (EBT). 140 scans were acquired in the continuous volume scanning mode (3 mm slice thickness). 100 ml of contrast material were intravenously administered. Studies were reviewed for the presence of acute pulmonary embolism and the number and location of interpulmonary, interlobar or intersegmental saddle emboli. Saddle emboli were defined as emboli extending across the bifurcation of a vessel into both branches by at least 5 mm each.
30 of 128 (23.4 %) patients (15 men; mean age 59 +/- 17 years) had acute pulmonary embolism. One or more saddle emboli were present in 20 of 30 patients (66.7 %), a total of 77 saddle emboli were detected ranging from 1 to 10 per patient. Distribution of the saddle emboli in the 20 patients was as follows: 5 interpulmonary, 28 interlobar and 44 intersegmental.
Pulmonary saddle emboli are present in the majority of patients with acute pulmonary embolism. They are often multiple and may be found at different levels of the pulmonary arterial vasculature.
No preview · Article · Aug 2002 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: Multislice CT systems allow the simultaneous acquisition of multiple slices per gantry rotation. In combination with faster gantry rotation times of 0.5 seconds, the abdominal structures can be displayed in higher spatial and temporal resolution. In MS-CT of the liver it is possible to scan the entire organ with an optimal slice thickness of 2 - 3 mm within a defined perfusion phase in less than 10 seconds. This results in an improved detection and characterization of focal liver lesions. A high-quality, 3-dimensional reconstruction of the hepatic arterial and portalvenous system is obtained with the same data set. The diagnostic use of the simultaneously acquired perfusion data will lead to a better characterization of focal liver lesions in the future. The diagnostics of the pancreas also profits from MS-CT, especially for the detection of small tumors and the evaluation of resectability of a pancreatic carcinoma. All abdominal structures can be displayed in a coronal view without loss of image quality because of the almost isotropic voxels obtained. This proves to be beneficial for the preoperative diagnostics of renal cell carcinomas, especially if the tumor extension into adjacent organs (e. g., liver or spleen) in the longitudinal direction has to be evaluated. The multiplanar display and the sophisticated 3-dimensional reconstruction tools have a substantial value for the abdominal CT angiography. It proves to have a major diagnostic impact on acute abdominal aortic and visceral arterial diseases because even large distances in the z-direction can be covered with high spatial resolution.
No preview · Article · Apr 2002 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: The assessment of focal hepatic lesions is the most frequent reason for performing imaging studies of the liver. Such studies are performed in the staging or follow-up of various malignant tumors with the aim of detecting liver metastases, which may occur in one-third of all malignant tumors. About 90% of all malignant liver lesions are metastases. On the other hand, the majority of small focal liver lesions are benign even in patients with underlying malignant disorders. Thus, the imaging techniques used to evaluate the liver must achieve accurate depiction and characterization of both focal lesions and diffuse processes. Additionally, they should provide information on segmental and vascular anatomy to facilitate treatment planning. To accomplish these goals, high spatial resolution, dynamic contrast enhanced imaging, and multiplanar 2D and 3D reformation are all important. High spatial resolution improves evaluation of the liver. The use of thin sections is mandatory to facilitate the detection of small lesions since relatively large slices result in partial volume artifacts. Dynamic contrast-enhanced studies should reliably capture both the hepatic arterial and the portal-venous phase. Arterial phase imaging is crucial for the evaluation of many lesions, particularly hypervascular masses. This demands high temporal resolution with short acquisition times and a method for ensuring acquisition during the period of hepatic arterial perfusion. Accurate three-dimensional rendering of segmental and vascular anatomy can be helpful for surgical planning, including hepatic resection and liver transplantation. These goals can be achieved with multislice helical CT (MSCT).
[Show abstract][Hide abstract] ABSTRACT: Impact of different iodine concentrations on abdominal enhancement in biphasic multislice helical CT (MS-CT).
To evaluate if different iodine concentrations of a contrast material (c.m.) have an impact on abdominal enhancement in MS-CT during the arterial (AP) and portal venous phase (PVP).
75 patients underwent biphasic CT of the abdomen. They were assigned to three equally sized groups. For all patients a non-ionic c.m. (iopromide, Ultravist, Schering AG, Berlin) with different iodine concentrations and a constant total iodine load of 37 g with an injection flow rate of 4 ml/s was used. The volume of the c.m. differed depending on the iodine concentrations: group 1 (123 ml of 300 mgl/ml); group 2 (112 ml of 335 mgl/ml); group 3 (100 ml of 370 mgl/ml). The scan delay was optimized by using a bolus tracking device. The groups were compared concerning their mean enhancement of aorta, spleen, pancreas, and liver in the AP and PVP.
The comparison of the three groups showed an improved enhancement in aorta, spleen, and pancreas during the AP by using the higher c.m. concentrations. In the PVP the c.m. enhancement of aorta, liver, spleen, and pancreas was independent of the administered c.m. concentration.
Higher iodine concentrations of c.m. have a positive impact on abdominal enhancement during the AP. The concentration has no influence on the enhancement during the PVP of abdominal MS-CT.
No preview · Article · Nov 2001 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: Placement of an aortic wallstent for treatment of an abdominal aortic aneurysm (AAA) is a frequent therapeutic measure. Whereas AAA is known to mimic renal colic, aortic wallstent dislocation is a novel diagnostic problem. Herein, we report the first case of a patient with a dislocated aortic wallstent and subsequent aneurysm rupture and discuss appropriate diagnostic measures.
No preview · Article · Jul 2001 · Scandinavian Journal of Urology and Nephrology
[Show abstract][Hide abstract] ABSTRACT: To determine the value of multi-slice CT for the diagnosis of acute pulmonary embolism and an underlying venous thrombosis.
70 patients with clinically suspected acute pulmonary embolism were examined. Using multi-slice CT a combined examination of the pulmonary arteries and the veins of the lower limb, pelvis and abdomen was performed. Only one single bolus of 150 ml iopromid 300 was injected into a cubital vein with a flow of 4 ml/s. First, the pulmonary arteries were scanned with a slice thickness of 2.5 mm and a pitch of 1.5. On arrival of the contrast medium at the popliteal veins, indicated by bolus trakking, the veins of the lower limbs up to the end of the inferior vena cava were imaged using a slice thickness of 3.75 mm and a pitch of 1.5. The results could be compared with a ventilation-perfusion scan in 48 cases, with a Doppler ultrasound examination in 46 cases, and with a venography in 10 cases. Furthermore, the image quality of all arterial and venous regions was subjectively assessed.
In all patients who underwent multi-slice CT the pulmonary arteries as well as the veins of the lower half of the body could be recorded completely. Regarding the pulmonary arteries the image quality showed excellent results for the central and segmental arteries. The region up to the 3rd division in subsegmental branches could be sufficiently judged. More peripherally, a diagnostic assessment was not possible. The image quality of the veins was excellent in all sections, except the calf, where a reliable diagnosis could not be made. The comparison with the other techniques confirmed the superiority of multi-slice CT concerning the central and segmental pulmonary arteries and the veins from the popliteal vein to the inferior vena cava. In contrast, peripheral pulmonary emboli can be detected more certainly in ventilation/perfusion scans. The veins of the calf can be evaluated more reliably with venography.
Multi-slice CT proved to be an outstanding tool in the diagnosis of acute pulmonary embolism. The clinically suspected disease and a causing venous thrombosis can be detected in a fast and reliable way. At present, multi-slice CT is not suitable for the recognition of peripheral emboli. However, expected technical developments hold promise for future improvements.
No preview · Article · Jul 2001 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to determine the optimal scan parameters for the evaluation of experimental vascular stenoses with a multislice-helical CT.
A vascular phantom consisting of four tubes with an inner diameter of 8 mm and with experimental stenoses of 50%, 75% and 90% was scanned in different tube orientations using a multislice-CT scanner (LightSpeed QX/i, GE, Milwaukee, USA). Examinations were performed with increasing collimations (1.25-5 mm), tube currents (100-300 mA) and two different table speeds (0.75 HQ mode and 1.5 HS mode).
The most exact measurements were obtained in tubes angulated parallel to the scan direction with a collimation of 2.5 mm in the HQ mode (7.5 mm/rot.). An almost equivalent accuracy was obtained in the HS mode (15 mm/rot.) with a collimation of 2.5 mm when higher tube currents (300 mA) were employed. The degree of stenoses was overestimated when the tube was angulated perpendicular to the z-axis.
Multislice-CT provides a good detection rate of vascular stenoses especially at 0 degree and also at 45 degrees angulation in the HQ mode. The use of the HS mode with higher tube currents allows scanning of longer distances with almost identical accuracy.
No preview · Article · Dec 2000 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: Evaluation of different contrast-enhanced MR angiography imaging protocols for visualization of the entire aorta in breath-hold technique.
Three different CE (0.15 mmol/kg) MRA protocols were evaluated by phantom and patient studies: (1) two separate MRA with conventional application of the body-phased array coil; (2) a single-shot MRA with modified application of the body-phased array coil; (3) a single-shot MRA with the body coil. Duplex sonography, CTA and DSA were used as standard of reference.
In all examinations the entire aorta could be visualized. The best SNR was acquired with protocol (1). The SNR of protocol (2) was reduced if the sagittal body diameter of the patient was greater than 20 cm and decreased significantly with diameters over 30 cm. By the use of protocol (3) the SNR was notably poor. The quality scored for the visualization of the entire aorta was 97.5% (protocol 1); 92.5% (protocol 2); and 80.0% (protocol 3).
In most cases the modified application of the body-phased array coil allows the imaging of the entire aorta as a single-shot 3D CE MRA in diagnostic quality.
No preview · Article · Feb 2000 · European Journal of Radiology
[Show abstract][Hide abstract] ABSTRACT: To determine if magnetic resonance (MR) imaging can help determine the therapeutic approach in women with breast cancer.
Preoperative contrast-enhanced MR imaging of the breast was performed in 463 patients with probably benign lesions (n = 63), suspicious lesions (n = 230), or lesions highly suggestive of malignancy (n = 170) per established clinical, mammographic, and/or ultrasonographic (US) criteria. T1-weighted fast low-angle shot MR imaging was performed before and after administration of gadopenetetate dimeglumine. MR imaging findings were correlated with other imaging results and histopathologic findings. Special attention was paid to multifocality and multicentricity.
Histopathologic analysis revealed 143 benign and 405 malignant lesions. The sensitivity, specificity, and accuracy were 58%, 76%, and 62% for clinical examination; 86%, 32%, and 72% for conventional mammography; 75%, 80%, and 76% for US; and 93%, 65%, and 85% for contrast-enhanced MR imaging. Multifocality in 30 of 42 patients, multicentricity in 24 of 50 patients, and additional contralateral carcinomas in 15 of 19 patients were depicted with MR imaging alone. Due to the MR imaging findings, therapy was changed correctly in 66 patients (14.3%); unnecessary open biopsy was performed in 16 patients (3.5%).
Contrast-enhanced MR imaging of the breast is highly sensitive for invasive breast cancer. MR imaging may reveal unsuspected multifocal, multicentric, or contralateral breast carcinoma and result in therapy changes.
[Show abstract][Hide abstract] ABSTRACT: Scan protocol optimization and value of a multi-row-detector helical CT (MS-CT) in comparison to a single-row-detector spiral CT (SS-CT) for imaging of focal liver lesions.
The ability of a MS-CT with different scan parameters (slice thickness, scan mode, table-speed, reconstruction interval) for the detection of low-contrast objects was evaluated with a liver phantom and compared to a SS-CT. The clinical value (detection and characterization) of MS-CT with various slice thicknesses (3.75, 5, 7.5 mm) was compared intraindividually in 20 patients with a total of 43 benign and malignant lesions.
In the experimental study the MS-CT reached the same detection rates for low-contrast objects despite a three-times faster scan-time compared to a SS-CT. The slice thicknesses of 3.75 and 5 mm proved to be optimal and were superior to a thickness of 7.5 mm for the detection and characterization of liver lesions. A distinct separation between arterial and portal venous phase was achieved by this protocol.
The MS-CT allows a reliable acquisition of the entire liver parenchyma in defined perfusion phases. It improves the detection and characterization of focal liver lesions with optimized scan parameters with a significantly faster scan time than with the SS-CT.
[Show abstract][Hide abstract] ABSTRACT: Acute diseases of the central arteries require an immediate investigation. An efficient, fast and reliable diagnosis is necessary because of the high mortality, if the patient remains untreated. These requirements are perfectly fulfilled by the new CT-techniques.
Suspected aortic diseases were examined with a new multi-slice helical CT. The thoracic or the abdominal aorta as well as the entire vascular tree from the supra-aortic branches to the inguinal arteries were investigated with different CT protocols. The slice-thickness and the scan mode were changed while the total examination time was kept constant for the first two groups. In the third group a monophasic examination was compared to a biphasic one.
In the diagnosis of acute aortic diseases multi-slice helical CT proved to be a fast and reliable method with all scan protocols. The objective measurements of contrast homogeneity and image quality were comparable in the first two groups. The monophasic contrast medium injection protocol was superior to the biphasic administration mode.
Multi-slice helical CT appears to be a very effective approach for the diagnosis of acute aortic diseases and seems to be the new gold standard.
[Show abstract][Hide abstract] ABSTRACT: Purpose: Scan protocol optimization and value of a multi-row-detector helical CT (MS-CT) in comparison to a single-row-detector spiral CT (SS-CT) for imaging of focal liver lesions.
Materials and Methods: The ability of a MS-CT with different scan parameters (slice thickness, scan mode, table-speed, reconstruction interval) for the detection of low-contrast objects was evaluated with a liver phantom and compared to a SS-CT. The clinical value (detection and characterization) of MS-CT with various slice thicknesses (3,75, 5, 7,5 mm) was compared intraindividually in 20 patients with a total of 43 benign and malignant lesions.
Results: In the experimental study the MS-CT reached the same detection rates for low-contrast objects despite a three-times faster scan-time compared to a SS-CT. The slice thicknesses of 3,75 and 5 mm proved to be optimal and were superior to a thickness of 7,5 mm for the detection and characterization of liver lesions. A distinct separation between arterial and portal venous phase was achieved by this protocol.
Conclusion: The MS-CT allows a reliable acquisition of the entire liver parenchyma in defined perfusion phases. It improves the detection and characterization of focal liver lesions with optimized scan parameters with a significantly faster scan time than with the SS-CT.
[Show abstract][Hide abstract] ABSTRACT: Akute Erkrankungen der Aorta im Körperstamm stellen eine lebensbedrohliche Situation für den betroffenen Patienten dar, so daß ein rasches Handeln zwingend erforderlich ist. Voraussetzung hierfür ist eine leistungsfähige, schnelle und zuverlässige Diagostik, die von der neuen CT-Technik in nahezu idealer Weise realisiert werden kann.
Methoden: Bei klinischem Verdacht auf eine Aortenerkrankung wurden Untersuchungen mit einer neuen Mehrzeilen-Spiral-CT (MZ-SCT) durchgeführt. Die Aorta thoracalis, die Aorta abdominalis oder der gesamte Gefäßbaum von den supraaortalen Ästen bis zu den Inguinalarterien wurden mit verschiedenen Protokollen untersucht. In den ersten beiden Gruppen wurden bei konstanter Untersuchungszeit die Schichtdicke und die Tischvorschubgeschwindigkeit variiert. In der dritten Gruppe wurde eine monophasische mit einer biphasischen Untersuchung verglichen.
Ergebnisse: In der Diagnostik von aortalen Erkrankungen erwies sich die MZ-SCT als schnelle und verläßliche Methode mit allen Protokollen. Die objektive Messung der Kontrasthomogenität und die subjektiven Abbildungsqualitäten waren in den ersten beiden Gruppen vergleichbar. Das monophasische Vorgehen war der biphasischen Untersuchung überlegen.
Schlußfolgerung: Die MZ-SCT ist bei Anwendung geeigneter Untersuchungsprotokolle heute der Goldstandard in der Diagnostik akuter Aortenerkrankungen.
[Show abstract][Hide abstract] ABSTRACT: Presentation and evaluation of slice sensitivity profile and pixel noise of multi-slice CT in comparison to single-slice CT.
Slice sensitivity profiles and pixel noise of a multi-slice CT equipped with a 2D matrix detector array and of a single-slice CT were evaluated in phantom studies.
For the single-slice CT the width of the slice sensitivity profiles increased with increasing pitch. In spite of a much higher table speed the slice sensitivity profiles of multi-slice CT were narrower and did not increase with higher pitch. Noise in single-slice CT was independent of pitch. For multi-slice CT noise increased with higher pitch and for the higher pitch decreased slightly with higher detector row collimation.
Multi-slice CT provides superior z-resolution and higher volume coverage speed. These qualities fulfill one of the prerequisites for improvement of 3D postprocessing.
No preview · Article · Oct 1999 · RöFo - Fortschritte auf dem Gebiet der R
[Show abstract][Hide abstract] ABSTRACT: To evaluate the feasibility and diagnostic value of there different MR angiographic imaging techniques for the assessment of the central body veins.
25 investigations of the central veins were performed with an ECG-triggered black-blood HASTE sequence, a segmented 2D cine FLASH sequence and a contrast-enhanced 3D-FISP angiography. The results of the MR-studies were compared with those of spiral CT or venography.
The HASTE sequence was suitable for the assessment of the complete central body vein system also in less cooperative patients. The combination with the 2D cine FLASH sequence enabled the detection of intravascular tumors or thromboses and the graduation of subtotal occlusions. The involvement of the right atrium was proved in 2/2 cases. The attachment at the vessel wall could be assessed. Only contrast-enhanced 3D MRA visualized the renal veins and complex collaterals sufficiently. But this procedure has to be done in a strict breath-hold technique.
In the present study all thromboses and tumor cones of the central body veins were detected with the combined use of HASTE/Cine FLASH. For the assessment of complex collaterals and the renal vessels the application of contrast-enhanced 3D-MRA techniques is necessary.
No preview · Article · Sep 1999 · RöFo - Fortschritte auf dem Gebiet der R