Measurement of hepatic perfusion with dynamic computed tomography: assessment of normal values and comparison of two methods to compensate for motion artifacts.

RATIONALE AND OBJECTIVES: To assess normal values of hepatic perfusion by dynamic, single-section computed tomography, to compare two methods of data processing (a smoothing with a fitting procedure), and to evaluate the influence of motion artifacts. METHODS: Twenty-five volunteers with no history or suspicion of liver disease were examined (age range, 32.8-81.1 years). All examinations were subjectively ranked into groups 1 through 3 according to the degree of motion artifacts (negligible, moderate, severe). All data were processed with a smoothing procedure and a pharmacokinetic fitting procedure (TopFit). The arterial, portal venous, and total hepatic perfusion; the hepatic perfusion index (HPI); and the arterial/portal venous ratio (A/P ratio) were calculated with both procedures. RESULTS: Mean hepatic perfusion, as assessed with the fitting procedure and the smoothing procedure, respectively, was as follows: arterial, 0.20 and 0.22 mL x min(-1) x mL(-1); portal venous, 1.02 and 1.24 mL x min(-1) x mL(-1); total perfusion, 1.22 and 1.47 mL x min(-1) x mL(-1); HPI, 16.4% and 15.4%; and A/P ratio, 0.20 and 0.19. The differences were significant for the portal venous and total hepatic perfusion. The portal venous and total hepatic perfusion values showed significant differences between group 1 and groups 2 and 3 for both procedures. HPI and the A/P ratio showed no significant differences at all. CONCLUSIONS: Motion artifacts and the type of data processing influence the assessment of the arterial, portal venous, and total hepatic perfusion but do not influence measurement of the HPI and the A/P ratio.

Timing of the hepatic arterial phase during contrast-enhanced computed tomography of the liver: assessment of normal values in 25 volunteers.

OBJECTIVES: To define normal values of the beginning and duration of the hepatic arterial phase (HAP) during contrast-enhanced computed tomography (CT). METHODS: Twenty-five volunteers (16 men, 9 women; mean age, 60.0 years) without history or suspicion of liver disease were examined with dynamic single-section CT. Scanning was performed at a single level that included the liver, aorta, and portal vein. A series of 25 scans was obtained over a period of 88 seconds (1 baseline scan followed by 16 scans every 2 seconds and 8 scans every 7 seconds) beginning with the injection of a bolus of contrast agent (40 mL, 10 mL/s) and a 40-mL NaCl bolus chaser. Contrast enhancement in the liver, aorta, and portal vein was measured with regions of interest, and time-density curves were obtained. These data were processed with a pharmacodynamic fitting program and the duration of the HAP was calculated. The onsets of the HAP and the portal venous phase were assessed as lag times, referring to the beginning of enhancement in the abdominal aorta. RESULTS: The mean lag time of the HAP was 5.4 seconds after the aorta and the mean duration was 8.6 seconds. The mean lag time of the portal venous phase was 13.9 seconds after the aorta. CONCLUSIONS: These data can be used to optimize protocols for routine CT. Because of the short duration of the HAP, imaging of the entire liver during this phase is possible only with multidetector CT scanners.

[The value of sonography in the intensive care unit for the diagnosis of diaphragmatic paralysis]. / Wertigkeit der Sonographie auf der Intensivstation zur Diagnostik von Zwerchfellparesen.

PURPOSE: To assess the value of bedside sonography in the detection of diaphragmatic paralysis in patients in the intensive care unit. METHODS: In this study, 100 patients who were admitted to the intensive care unit after thoracic operations were evaluated. Sonography of each hemidiaphragm was performed with coronal scans at the mid-axillary line on both sides with the patient supine. Absent and paradoxical diaphragmatic movement was considered to be indicative of diaphragmatic paralysis. All patients underwent additional fluoroscopy within 5 days. RESULTS: In 13 patients (13%) sonography revealed diaphragmatic paralysis. All these results were confirmed with fluoroscopy resulting in a sensitivity and specificity for sonography of 100%. CONCLUSION: Bedside sonography of the diaphragm at the intensive care unit is a reliable tool for diagnosing diaphragmatic paralysis.

Hepatic perfusion after liver transplantation: noninvasive measurement with dynamic single-section CT.

PURPOSE: To compare hepatic perfusion values after orthotopic liver transplantation with those in healthy volunteers. MATERIALS AND METHODS: Dynamic single-section computed tomography (CT) of the liver was performed in 50 participants, including 30 study patients who had undergone orthotopic liver transplantation and had no clinical evidence of postoperative complications (mean age, 53.7 years) and 20 healthy volunteers (control subjects) (mean age, 59.0 years). CT scans were obtained at a single level to include the liver, spleen, aorta, and portal vein. Scans were obtained over 88 seconds (one baseline scan followed by 16 scans every 2 seconds and, then, eight scans every 7 seconds) beginning with the injection of 40 mL of contrast agent (flow rate, 10 mL/sec). On each CT scan, the attenuation of these organs was measured in regions of interest to provide time-attenuation curves. From these data, the arterial, portal venous, and total perfusion of the liver were calculated, and the hepatic perfusion index was assessed. RESULTS: In control subjects and study patients, respectively, mean arterial hepatic perfusion was 0.16 and 0.25 mL/min/mL (P = .001 [two-tailed paired Student t test]), mean portal venous perfusion was 1.22 and 1.26 mL/min/mL, mean total liver perfusion was 1.38 and 1.50 mL/min/mL (difference not significant), and the mean hepatic perfusion index was 0.12 and 0.16 (P = .002). CONCLUSION: Arterial hepatic perfusion was significantly increased after orthotopic liver transplantation, but differences in portal venous and total liver perfusion were not significant. Dynamic single-section CT might also help evaluate hepatic vascular complications, chronic transplant rejection, and hepatic perfusion in liver cirrhosis.

Endocarditis and aortal embolization caused by Aspergillus terreus in a patient with acute lymphoblastic leukemia in remission: diagnosis by peripheral-blood culture.

Disseminated infection with Aspergillus terreus is a rare disease that affects only the immunocompromised host. We report a case of systemic infection with A. terreus resulting in endocarditis, aortic embolization, and splenic infarction in a patient with acute lymphoblastic leukemia. Diagnosis through peripheral blood culture, lack of pulmonary involvement, and onset of disease during complete remission from leukemia constitute uncommon features of this case.

Role of magnetic resonance imaging in renal transplant recipients with acquired cystic kidney disease.

OBJECTIVES: To evaluate the impact of magnetic resonance imaging (MRI) in renal transplant recipients whose ultrasound (US) examinations of the native kidneys have met the criteria of acquired cystic kidney disease (ACKD). METHODS: The US scans of 840 renal allograft recipients were prospectively studied. In addition, 46 of 169 patients diagnosed with ACKD by US scans underwent MR examination. MRI protocols included (a) T1 and T2-weighted fast spin echo imaging, (b) T2-weighted gradient echo imaging, and (c) gadolinium-enhanced T1-weighted imaging in 7 patients with evidence of complex cysts. In the case of complex lesions, both US and MRI follow-up examinations were performed between 6 and 12 months after the prior examination. RESULTS: US examination showed ACKD in 169 of 840 patients. In addition, US revealed 8 patients with renal cell carcinomas (RCC). Of these 8 patients, 7 had evidence of ACKD. The median number of cysts depicted on US examination in native kidneys of renal transplant recipients was 3 (range 0 to 10) on both sides. MRI revealed significantly more and smaller cysts compared to US. The median number of cysts was seven on the left and nine on the right native kidneys, respectively. MRI revealed 18 complex lesions in 7 patients. Thirteen of 18 complex lesions were undetected by US. CONCLUSIONS: MRI is superior to US in depiction of simple and complex lesions of native kidneys in renal allograft recipients. MRI exhibits no overestimation of the prevalence of ACKD on the basis of the US criteria already mentioned. Advantages of MRI do not justify routine screening tests by this imaging modality. However, MRI should be used for further evaluation of complex lesions detected by US.

Diaphragmatic dysfunction after heart or lung transplantation.

BACKGROUND: The aim of this study was to evaluate the incidence and outcome of diaphragmatic dysfunction in patients after heart or lung transplantation and to assess the value of bedside sonography for the detection of diaphragmatic dysfunction. METHODS: We prospectively evaluated 33 heart transplant recipients and 27 lung transplant recipients by use of sonography of the diaphragm and fluoroscopy. RESULTS: Diaphragmatic dysfunction, diagnosed with ultrasonography and confirmed with fluoroscopy, was present in four heart transplant recipients (12.1%) and two lung transplant recipients (7.4%) and such dysfunction led to a statistically significant higher incidence of pneumonia during hospitalization and a nonstatistically significant increased length of intubation compared with patients with normal diaphragmatic function. CONCLUSION: Diaphragmatic dysfunction, which can be reliably diagnosed with bedside sonography, is common after heart and lung transplantation and seems to have a negative influence on patient recovery.

Intraoperative and early postoperative colour Doppler sonography after carotid artery reconstruction: follow-up of technical defects.

We studied 50 patients with intraoperative colour-coded Doppler sonography (CCDS) after carotid artery reconstruction. Technical defects could be detected in 19 cases (38 %): residual plaques in 9, flaps in 8 and strictures in 2. In 9 cases (18 %) the carotid endarterectomy was revised. One residual plaque and one residual stricture caused thrombosis at the operative site a few hours postoperatively. One of the patients with residual plaques developed a high-grade stenosis within the follow-up period. Of the patients with residual plaques two had a medium-grade stenosis at follow-up. Six flaps decreased in size or disappeared within 1 week after operation. No patient with a flap developed a stenosis within the follow-up period. Our findings seem to indicate that correction of intimal flaps less than 10 mm in size is not necessary.

Successful treatment of a high-risk choriocarcinoma in Figo stage IV (WHO score 12).

In the present report, a case of high-risk choriocarcinoma (Figo stage IV, WHO score 12) with persisting vaginal and urethral bleedings is described. In addition to a course of multiagent chemotherapy, arterial embolization of both iliac vessels using Gianturco coils was carried out. This caused a dramatic improvement of the patient's general condition. A subsequently performed laparatomy with extirpation of the uterus and both adnexa finally led to remission.

Spiral CT angiography: study of stenoses and calcification at the origin of the vertebral artery.

The origin of the vertebral artery may be difficult to show on sonography or conventional angiography. Our aim was to evaluate the accuracy of CT angiography (CTA) in detecting arteriosclerotic changes in the first segment (V1) of the vertebral artery. We performed CTA and intra-arterial digital subtraction angiography (DSA) on 24 patients with vertebrobasilar insufficiency. The ostium and the V1 segment were examined. Stenosis was assessed on a three-grade scale, and calcification and the degree of kinking were recorded. DSA and CTA results were compared. The ostium of the artery was seen in all cases on CTA and in 33 of 47 cases with DSA. All ostial stenoses diagnosed on DSA were seen with CTA. CTA revealed 4 stenoses in cases in which angiography proved inadequate, 11 zones of calcification and 5 cases of luminal reduction due to calcified plaques undetected on DSA. In the V1 segment DSA and CTA showed 3 stenoses, 9 cases of kinking, 1 of coiling and 4 stenoses due to kinking. CTA also demonstrated 4 additional stenoses, 2 cases of kinking and 3 stenoses due to kinking.

Pseudopericardial effusions in heart transplant recipients.

BACKGROUND: The objective of this study was to determine the nature of sonographically observed band-shaped, homogeneous, almost echo-free structures located ventral to the right ventricle of the heart in heart transplant recipients. METHODS: A total of 212 consecutive heart transplant recipients was evaluated sonographically. RESULTS: In 18 of the 212 patients (8.5%) band-shaped structures were detected, and these structures were proved with computed tomography or magnetic resonance imaging to be caused by mediastinal fat. CONCLUSIONS: A sonographically demonstrable, almost echo-free band-shaped structure located ventral to the heart should not be misinterpreted as localized pericardial effusion.

Coefficient of variation: a powerful Doppler ultrasonographic parameter for detection of renal artery stenosis.

The aim of our study was to objectively compare the effectiveness of various Doppler parameters in the diagnosis of renal artery stenosis. In three sheep, variable degrees of renal artery stenosis were induced and renal segmental arteries were investigated using pulsed Doppler sonography. In each animal the standard deviation of the instantaneous peak velocity within one cardiac cycle normalized by the mean peak velocity (coefficient of variation) had significantly higher normalized regression coefficients (k* = -0.215, average of three animals) when compared to resistive index (k* = -0.090) and acceleration index (k* = -0.069). In each individual animal, coefficient of variation detected lower pressure gradients (6.3 mm Hg, average value) than did resistive index (13.4 mm Hg) or acceleration index (17.3 mm Hg). The coefficient of variation may detect the presence of pressure gradients in renal artery stenosis more accurately than acceleration index or resistive index.

Stenoses of the first segment of the vertebral artery: difficulties in angiographic diagnosis.

Pathology at the origin of the vertebral artery may be the cause of incapacitating vertebrobasilar insufficiency (VBI). Preoperative diagnosis is made primarily on angiographic criteria. We compared intraoperative and angiographic findings in 30 patients and found important diagnostic discrepancies in patients with a caudal, ventral or dorsal origin of the vertebral artery. In their angiograms, vessel superimposition led us to over look 3 ostial stenoses and 10 stenoses due to kinking. Angiographic assessment of patients with VBI can be difficult. Adequate visualisation of the origin of the vertebral artery is mandatory for accurate diagnosis.

Intrarenal Doppler ultrasonography: which vessel should be investigated?

The aim of our study was to determine whether the site of intrarenal Doppler measurement influences diagnosis of renal artery stenosis. In an experimental test, three sheep with variable degrees of renal artery stenosis were investigated. In each animal, the resistive index from renal segmental arteries correlated better with mean pressure gradient (r = 0.85, 0.71, 0.85) and had lower standard deviation (s = 0.02 to 0.05) than resistive index from interlobar arteries (r = 0.48, 0.54, 0.61) (s = 0.03 to 0.11). In two animals the difference was significant (correlation: P < or = 0.01, P = 0.13, P < or = 0.05; standard deviation: P < or = 0.01, P < or = 0.34, P < or = 0.05). For detecting renal artery stenosis, vessels within the renal sinus should be used for Doppler sampling.

Quantification of pleural effusions: sonography versus radiography.

PURPOSE: To develop a practical method of estimating the volume of pleural effusions with sonography. MATERIALS AND METHODS: Fifty-one patients underwent sonography of the pleural space while supine. Sonographic results and results of lateral decubitus radiography were compared with actual effusion volumes. The maximum thickness of the pleural fluid layer was measured with both modalities, while actual effusion volume was determined by means of complete drainage. RESULTS: Sonographic measurements correlated statistically significantly better with actual effusion volume (r = .80) than did radiographic measurements (r = .58) (P < or = .05). With sonographic measurement, an effusion width of 20 mm had a mean volume of 380 mL +/- 130 (standard deviation), while one of 40 mm had a mean volume of 1,000 mL +/- 330. Prediction error with sonographic measurement (mean, 224 mL) was statistically significantly less (P < or = .002) than that with radiographic measurement (mean, 465 mL). CONCLUSION: In quantification of pleural effusions, the sonographic measurement method presented is preferable to radiographic measurement.

[Rate of thrombosis after cava filter implantation. Long-term results]. / Thromboserate nach Kavafilterimplantation. Langzeitergebnisse.

Thrombosis of the access site and occlusion of the inferior vena cava after placement of an inferior vena caval filter are known complications of caval interruption. 30 patients were evaluated with colour-coded Doppler sonography 4 to 66 months (average 2.5 years) after percutaneous placement of either a Günther filter, a Bird's Nest filter or a Simon-Nitinol filter. One right internal jugular vein had post-thrombotic alterations. One inferior vena cava was found to be occluded 15 months after Simon-Nitinol filter placement. The long-term occlusion rates of access site and inferior vena cava after percutaneous filter introduction are low. These two factors need not be considered if implantation of a caval filter is contemplated.

Aprotinin does not decrease early graft patency after coronary artery bypass grafting despite reducing postoperative bleeding and use of donated blood.

Forty-five male patients with planned coronary artery bypass operation were randomized in a double blind fashion to receive either 6 million kallikrein inactivator units of aprotinin (high-dose group), 2 million kallikrein inactivator units of aprotinin (low-dose group), or placebo (control group). Postoperative bleeding was significantly decreased in both aprotinin groups in comparison to that in the control group (590 ml [290 to 1800 ml] high-dose group and 650 ml [280 to 1900 ml] low-dose group versus 920 ml (350 to 2700 ml) control group, p < 0.001). There was no difference between the two aprotinin groups. The need for postoperative blood transfusion was significantly lower in the aprotinin groups (1.46 [0 to 4] blood units high-dose group and 1.65 [0 to 5] blood units low-dose group versus 2.43 [0 to 7] blood units control group, p < 0.05). All patients underwent coronary angiography between the seventh and twelfth postoperative day. No difference was found among the three groups in patency of vein grafts-93.8% in the high-dose group, 94.5% in the low-dose groups, and 93.3% in the control group. Therefore, aprotinin significantly reduced postoperative bleeding and transfusion requirement after coronary artery bypass grafting without influencing early graft patency.

Mesh tube-calibrated varicose veins for coronary artery bypass grafting.

Complex arterial bypass grafting may be contraindicated for patients with multivessel disease and inadequate saphenous veins. In such cases varicose veins may be used as bypass conduits after calibration by insertion into mesh tubes. After in vitro and experimental testing, as well as gratifying results in infrainguinal arterial reconstructions, wrapped varicose vein grafts in addition to arterial bypass grafts were used in 6 patients undergoing coronary artery bypass grafting.

[Stenoses and occlusions of the abdominal aorta in patients less than 40-years old]. / Stenosen und Verschlüsse der Aorta abdominalis bei Patienten unter 40 Jahren.

Stenosis or occlusion of the abdominal aorta in patients under 40 years of age is either due to a congenital malformation (abdominal aortic coarctation) or due to idiopathic aortitis (Takayasu's arteritis). Some authors, however, consider abdominal aortic coarctation as a subtype of Takayasu's arteritis. We evaluated 9 of our cases and 108 well-documented cases from the literature to help decide the question whether abdominal aortic coarctation is an entity of its own or a subtype of Takayasu's arteritis. In coarctation there is a slight male predominance, patients are usually younger than 20 years of age, and the short aortic stenosis is suprarenal with involvement of the renal arteries. In Takayasu's arteritis females are predominantly affected, patients are usually over 20 years of age, and the long aortic stenosis or occlusion is infrarenal without involvement of the renal arteries. Abdominal aortic coarctation must therefore be considered as a separate disease. Aortography is important, because the morphology of aortic alterations often allows a radiological diagnosis.