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J O Balzer

Publications and source records attributed to J O Balzer.

At least 37 records · Page 2Linked to original sources
PubMed1999

Stent-supported reconstruction of the aortoiliac bifurcation with the kissing balloon technique.

BACKGROUND: Bilateral iliac artery obstructions involving the aortic bifurcation or high-grade stenosis of the abdominal aorta are not usually considered an indication for percutaneous treatment. The purpose of the present study was to evaluate the initial and long-term results of primary stent implantation for reconstruction of the aortic bifurcation. METHODS AND RESULTS: In 48 patients with obstructions of the aortoiliac segment, primary stent implantation was performed with the "kissing balloon technique." Preinterventional angiography showed bilateral stenoses (>85%) of the proximal common iliac arteries in 25 patients, unilateral occlusions and contralateral stenosis in 22 patients, and bilateral occlusion in 1 patient. In 7 cases, stents were placed for the treatment of high-grade infrarenal aortic stenoses. After excimer laser-assisted recanalization of the common iliac artery obstructions, the aortic bifurcation was reconstructed with the bilateral simultaneous implantation of Palmaz stents (diameter, 7 to 8 mm). Stents used for the treatment of aortic stenoses (Palmaz, n=6; Gianturco, n=1) had a diameter ranging from 20 to 25 mm. In all patients, stents were placed successfully (residual stenosis <30%) and without complications. A clinical improvement of +2 to +3 according to American Heart Association criteria was observed in 41 and 7 patients, respectively. Follow-up was performed clinically (standardized treadmill testing and color-coded Doppler ultrasound) and angiographically. The primary angiographic patency rate (24-month follow-up) was 86.8%. In 3 patients, angiography revealed significant restenoses, which were successfully treated with percutaneous transluminal angioplasty. CONCLUSIONS: Primary stent implantation with the kissing balloon technique is safe and effective for the treatment of aortoiliac obstructions involving the aortic bifurcation and represents a true endovascular alternative to surgery.

Angioplasty, Balloon↗
PubMed1998

[Diagnosis of the abdominal vascular system by means of electron-beam computed tomography (EBT)].

PURPOSE: To evaluate the potential of electron-beam computed tomography (EBT) in the pre- and postinterventional assessment of vascular abdominal pathologies. MATERIAL AND METHODS: Forty patients with implanted transjugular portosystemic shunt (TIPS), 12 patients with peripheral arterial occlusive disease and 8 patients with infrarenal abdominal aortic aneurysm after endovascular implantation of bifurcation stents were prospectively examined with contrast-enhanced EBT during one year. The evaluation included analysis of time-density curves (TDC) and 3D reconstructions. Results were compared with Doppler sonography and/or DSA. RESULTS: In 30 of 40 TIPS patients, identical results were found with EBT, Doppler sonography and/or DSA. Reduced perfusions of the TIPS, which were subsequently confirmed by DSA, could not be shown with EBT in 3 patients. Nine of 12 patients with peripheral arterial occlusive disease and angiographically proven stenosis (> 75%) showed a reduced and delayed peak density of the time-density curves. The quantification of arterial stenosis, however, did not follow the angiographic values. In all patients with the implanted bifurcation stents, EBT could correctly exclude a leakage of the stent. CONCLUSION: EBT has certain advantages over conventional spiral CT in the evaluation of abdominal vascular pathologies due to the additional assessment of perfusion parameters. Clinical indications for the use of EBT are seen especially in the postinterventional follow-up of patients with implanted stents.

Abdomen↗
PubMed1998

Initially unresectable hilar cholangiocarcinoma: hepatic regeneration after transarterial embolization.

PURPOSE: To assess with volumetric computed tomography (CT) the pattern and extent of hepatic regeneration induced with transarterial embolization of initially unresectable hilar cholangiocarcinoma (Klatskin tumor). MATERIALS AND METHODS: In this prospective study, 13 patients (four men, nine women) with hilar cholangiocarcinoma, aged 43-74 years (mean +/- 1 standard deviation, 59.9 years +/- 9.6), underwent preoperative embolization of the right hepatic lobe. Embolization was performed transarterially by using four to 15 embolization coils. Volumetric measurements of the entire liver, left hepatic lobe, and spleen were performed with contrast material-enhanced and unenhanced helical CT before and after embolization in all patients. RESULTS: After right lobe embolization, volumetric helical CT measurements revealed a 2%-33% decrease (mean, 10%) in the volume of the affected right hepatic lobe, an 11%-68% increase (mean, 37%) in the volume of left hepatic lobe parenchyma, and variations in splenic volume of -5% to +28% (mean, +11%). Nine patients underwent extended hepatectomy 27-75 days (mean, 44 days) after embolization. No patient had severe complications due to embolization. CONCLUSION: In patients with an initially unresectable bilateral Klatskin tumor, right lobar arterial coil embolization results in enlargement of the left hepatic lobe (as verified with volumetric helical CT), thus allowing right hemihepatectomy.

Adult↗
PubMed1997

[Dynamic and static MRI using superparamagnetic MRI contrast medium Resovist for visualizing primary and secondary liver tumors].

PURPOSE: To analyse characteristics of benign and malignant liver tumours in dynamic and static MR imaging with the superparamagnetic MR contrast medium Resovist. MATERIAL AND METHODS: All 30 patients were examined on a 1.5 Tesla MR unit (Magnetom 63 SP, Siemens AG, Erlangen, Germany) using proton density (PD) weighted (w), T2-weighted-spin-echo, a T1-weighted SE, and a T1-weighted FLASH-2 D gradient echo (GRE) sequence before, during and after the application of Resovist. Dynamic imaging was performed using a T2-weighted GRE-sequence (TurboFLASH; TR/TE = 11/30; flip angle = 10 degrees; Tl = 600 ms). Histopathology revealed benign liver lesions in 8 patients and malignant lesions in 22 patients. RESULTS: Dynamic T2-weighted sequence revealed an early loss of signal intensity in normal liver parenchyma (percentage signal intensity loss (PSIL) = 40.0 +/- 12.2% by 4 mumol Fe/kg, 47.2 +/- 18.8% by 8 mumol Fe/kg and 62.7 +/- 13.0% by 16 mumol Fe/kg), in the spleen, as well as in FNH (PSIL = 49.5 +/- 7.3% by 8 mumol Fe/kg), and regenerating nodules in the first minute after application of Resovist. In two of 4 cases with HCC a short drop in signal intensity was immediately observed after the application, whereas signal intensity remained unchanged in all other malignant liver tumours. Enhanced PDw and T2-weighted SE-sequences revealed an improved detection and delineation of malignant liver lesions versus plain MR imaging. 17 liver lesions of a size lower 10 mm were additionally detected in postcontrast T2-weighted SE-sequences in 4 patients. CONCLUSION: Dynamic and static versus plain MR imaging of primary and secondary liver lesions is markedly improved by the superparamagnetic contrast material Resovist, especially in case of intravenous bolus application of this liver-specific contrast medium.

Adult↗
PubMed1996

[Early clinical experiences with MR-guided laser-induced thermotherapy (LITT) of liver metastases in preoperative care].

PURPOSE: To evaluate the LITT-induced changes with the aid of MRT and correlate these with histopathological findings. MATERIAL AND METHODS: Five patients with solitary colorectal liver metastases were treated by means of MR-guided LITT before liver resection. Application time and energy of the Nd:YAG laser (1064 nm) was 10-20 minutes and 4.5-8.8 W. MRT monitoring during the LITT was carried out with temperature-sensitive T1 weighted sequences (FLASH-2-D, turbo FLASH). The extent of the induced necrosis as seen on MR was compared with the unfixed specimen and with the histopathological findings. RESULTS: The extent of necrosis visible by MRT correlated with the histopathological findings with an accuracy of 95.3% +/- 4.2%. Following single treatments (three cases) the metastases suffered a reduction of 24%-55% of their original volume. In two patients a second application produced laser-induced necrosis of 78% and 98% of volume. In these two patients a temperature sound was used for measuring regional heating and showed an exact correlation with MR thermometry. CONCLUSION: The results of pre-operative MR-guided LITT indicates the potential of this form of treatment for obtaining reproducible tumor necrosis of liver metastases.

Aged↗
PubMed1996

Magnetic resonance imaging of focal liver lesions. Comparison of the superparamagnetic iron oxide resovist versus gadolinium-DTPA in the same patient.

RATIONALE AND OBJECTIVES: The authors assess the efficacy of static and dynamic magnetic resonance (MR) imaging using the superparamagnetic iron oxide SHU-555A (Resovist) versus standard dose of gadolinium (Gd)-DTPA in patients with focal liver lesions. METHODS: Magnetic resonance imaging was performed in 30 patients suffering from histopathologically verified malignant (n = 22) and benign (n = 8) liver lesions. T2-weighted conventional and fat-suppressed as well as T1-weighted sequences were used before, during, and after fast intravenous administration of Resovist (1 mL/minute) at three doses of 4, 8, and 16 mumol/kg body weight. One week before the Resovist-enhanced MR imaging study 20 patients underwent Gd-DTPA-enhanced MR imaging. RESULTS: Detection rate was improved for metastatic lesions revealing 36 lesions unenhanced versus 53 focal lesions using Resovist-enhanced MR imaging. Gadolinium-DTPA-enhanced scans showed no additional lesion versus unenhanced and Resovist-enhanced MR imaging. Static and dynamic imaging demonstrated no measurable percentage signal intensity loss (PSIL) using Resovist-enhanced MR imaging versus a percentage enhancement of 79.7% in Gd-DTPA enhanced scans. In the dynamic T2-weighted sequences, hepatocellular carcinoma nodules (n = 4) showed a rapid decrease in signal intensity starting at 44 seconds. Postinfusion of Resovist followed by a low, constant increase in signal intensity. Gadolinium-DTPA enhanced scans showed a percentage enhancement of 73.4 focal nodular hyperplasia (FNH) and hemangioma revealed a strong and early dose-dependent PSIL 44 to 60 seconds postinfusion with a prolonged signal loss for the FNH in the late study. Statistical evaluation revealed a statistically significant superiority of Resovist-enhanced MR imaging concerning the detection and delineation of focal liver lesions compared with unenhanced and Gd-DTPA enhanced scans (P < 0.05). CONCLUSIONS: The fast infusion of the new superparamagnetic contrast agent Resovist shows advantages for dynamic and static MR imaging of focal liver lesions.

Carcinoma, Hepatocellular↗
PubMed1996

Base of skull, nasopharynx, and parapharyngeal space.

The base of skull, the nasopharynx, and the parapharyngeal space are among the most anatomically complex regions of the body. When pathologic changes arise in these areas, the close topographic relationship of soft-tissue structures and central nervous system structures, often separated only by an osseous or a thin soft tissue layer, generally necessitates sensitive diagnostic and complex therapeutic procedures.

Brain Diseases↗
PubMed1996

[Perioperative evaluation of internal carotid artery stenoses: value of multislab MR angiography].

PURPOSE: Evaluation of the diagnostic potential of high resolution multislab 3D-TOF-magnetic resonance angiography (MRA) in the pre- and postoperative assessment of carotid artery stenosis in comparison to conventional angiography. METHODS: 120 Patients were evaluated with MRA and DSA prior to carotid endarterectomy (CEA). Additionally 26 patients underwent MRA after CEA. All MRA examinations were carried out on a 1.5 T MR-unit (Siemens Magnetom SP63) using a Helmholtz surface coil. For the visualization of the vascular structures in the head and neck region, flow compensated GE-sequences were employed. Both original MRA data set and MIP angiograms were included in the evaluation. The determination of the extent of stenoses was performed according to the recommendation of NASCET. RESULTS: In 195 (92.9%) of 210 cases included in the review MRA revealed the same results as DSA (grade I+II: 114, grade III: 24, grade IV: 44, grade V: 13). None of the cases showed a deviation higher than one grade. The sensitivity and specificity of hemodynamic relevant stenoses (> 60%) was 0.964 respectively 0.952. 23 out of 26 patients with postoperative follow-up examination revealed regular reperfusion of the former affected internal carotid artery. The remaining 3 patients showed a restenosis of the operated vessel (n = 2) and a reocclusion of the ICA after surgery (n = 1). MRA proofed to be an accurate and reliable method for the perioperative evaluation of vascular structures in the head and neck region. Despite of some drawbacks MRA reached a high accuracy in the diagnostic imaging before and after CEA. MRA is accurate and useful in screening carotid artery diseases. The indication of MRA employment therefore not only covers the screening of vascular structures but also includes pre- and postoperative evaluation of vascular stenoses.

Adult↗
PubMed1995

[Multiple slab MR angiography of the A. carotis interna: a preoperative comparative study].

PURPOSE: With the introduction of MR angiography (MRA) into clinical routine, arteriosclerotic lesions of the supraaortic vessels may be well demonstrated. MATERIAL AND METHODS: The comparison between Multislab MRA (gradient echo, TOF) and X-ray angiography (XRA) as reference in 70 patients suspicious of stenotic lesions in the internal carotid artery proved the high reliability of these methods. RESULTS: In determining the degree of stenosis, according to the NASCET study (North American Symptomatic Endarterectomy Trial), a correlation between MRA and XRA of 92.3% could be calculated. The principal problem of MRA is the overestimation of high-grade stenoses; we observed 5 false-positive results in severe stenosis. Sensitivity and specificity were 95.6 and 92.6%, respectively, for detection of severe (> 60%) stenosis. CONCLUSION: Despite its limitations, MRA is a clinically important noninvasive technique for preoperative evaluation of patients undergoing carotid endarterectomy.

Adult↗
PubMed1994

Kallman syndrome versus idiopathic hypogonadotropic hypogonadism at MR imaging.

PURPOSE: To identify morphologic differences between Kallman syndrome (KS) and idiopathic hypogonadotropic hypogonadism (IHH) and establish a role for magnetic resonance (MR) imaging in these disorders. MATERIALS AND METHODS: Twenty-eight patients were compared with 10 eugonal male volunteers. Eighteen patients had KS (hypogonadotropic hypogonadism with anosmia) and 10 had IHH. All participants underwent hormone analysis, a sniff-bottle smell test, and gadolinium-enhanced MR imaging. Changes in the hypothalamic-hypophyseal region and the rhinencephalon were evaluated. RESULTS: MR imaging revealed intracranial morphologic changes in all patients on plain T1-weighted sections. Seventeen patients with KS demonstrated aplasia of an olfactory bulb; one olfactory sulcus was absent in six, rudimentary in four, and normal in eight. Olfactory bulbs were present in all 10 IHH patients and three showed one slightly hypoplastic bulb. Ten patients with KS and three with IHH showed an enlarged paranasal sinus system. Further MR findings were similar. CONCLUSION: MR imaging demonstrates abnormalities of the rhinencephalon present in KS patients and occasionally absent in IHH patients.

Adult↗
PubMed1994

Glomus tumors of the skull base: combined use of MR angiography and spin-echo imaging.

PURPOSE: To evaluate the use of magnetic resonance (MR) angiography in the diagnosis of glomus tumors of the skull base. MATERIALS AND METHODS: In 40 patients with pulsatile tinnitus, spin-echo (SE) images, single sections, and maximum intensity projections from gradient-echo sequences, including arterial MR angiography and MR venography, were evaluated for tumor detection. Interpretations by two independent observers were correlated with findings from histologic examination, digital subtraction angiography, computed tomography, and clinical follow-up. RESULTS: Glomus tumors were detected near the tympanic plexus (n = 8) and close to the superior (n = 8) and inferior (n = 1) ganglia of the vagus nerve. Sixteen of 18 proved tumors were detected with SE images alone. Although four high-lying jugular bulbs were misinterpreted as tumor due to similar signal intensity, combined evaluation allowed differentiation between tumor and sinusal blood flow in all cases. CONCLUSION: The authors recommend combined SE imaging and MR angiography for ruling out tumor in patients with pulsatile tinnitus.

Adult↗
PubMed1993

[Magnetic resonance angiography--a new procedure for vascular imaging in the area of the head-neck].

Some six or seven years ago, digital subtraction angiography (DSA) was introduced as a new diagnostic tool in the evaluation of vascular lesions. In the diagnostic management of vascular disorders in the head and neck, DSA could replace conventional angiography almost completely. Now, a new angiographic technique has been developed--magnetic resonance angiography (MRA). In the present study 60 patients with vascular lesions of head and neck were examined with both DSA and MRA in order to compare the diagnostic value of these techniques. Our results indicate that MRA is at least equivalent in the evaluation of vascular disorders in head and neck region. In addition, the advantages of MRA compared to DSA are the following: (1) MRA is a non-invasive technique, thus reducing the angiographic risk. (2) MRA offers the possibility of multiplanar imaging. (3) MRA can be performed simultaneously with MRI if necessary. (4) Compared to other angiographic techniques the patient will not be exposed to radiation.

Angiography, Digital Subtraction↗
PubMed1993

[Venous MR angiography for the primary diagnosis and follow-up of sinus venous thrombosis. The correlation with the clinical picture and DSA].

30 patients clinically suspected of suffering from venous sinus thrombosis were examined by MRT with venous MR angiography (FLASH 2-D). In 8 patients selective arterial angiography was also performed and 5 patients were followed up by MR angiography after an interval of three months. The MRT images and individual MR angiography images were analysed and 3-D reconstruction performed. In 11 patients MR angiography correctly demonstrated venous sinus thrombosis; the most frequently affected were the superior sagittal sinus, the ascending cerebral veins and the transverse sinus. Compared with DSA, magnetic resonance angiography achieved a high degree of accuracy in our patients. It was significantly better in evaluating the basal sinus system whereas thrombosis of individual ascending veins was better shown by DSA. In summary, primary use of MRT and MR angiography is recommended for the diagnosis of venous sinus thrombosis.

Adult↗
PubMed1992

[MR angiography in neuropediatric problems: the technic and the clinical results].

31 children aged between 6 months and 14 years with various neurovascular abnormalities were examined by MR angiography in a prospective study. In order to test the sensitivity and specificity of the MR results, these were compared in 8 cases with the findings of digital subtraction angiography or conventional angiography. In 24 patients arterial MR angiography was performed; in 17 these showed anomalies or abnormalities of the intracranial vascular system. In 7 patients venous MR angiography was performed and demonstrated the presence of sinus thrombosis in 6 of these. Comparison between MR angiography and DSA showed agreement in 7 cases; in one patient the degree of a stenosis was exaggerated by MR. The results of this study indicate that arterial and venous MR is of great value as an additional study in paediatric neurovascular problems.

Angiography, Digital Subtraction↗
PubMed1992

[MR angiography for tumor diagnosis in the head-neck region: the study technic and clinical results].

40 normal individuals and 153 patients with lesions in the head and neck were examined by conventional imaging methods and by means of MR angiography (1.5-tesla Magnetom). The problems to be solved concerned the relationship between tumors and vessels and vascular anomalies and abnormalities at the skull base (56 cases), the facial skeleton (62 cases) and the neck (35 cases). Digital subtraction angiography was performed in 54 patients and the findings correlated with MR angiography. Optimal results were obtained by using a FISP 3D sequence; in this way arterial structures could be rendered reproducibly down to a diameter of 2 mm. The venous system in the head and neck was best shown by a FLASH 2D sequence. Correlation with arterial DSA showed high accuracy of MR angiography (91%) concerning displacement of vessels, the topography and the recognition of vascular occlusions. Our results indicate that MR angiography is a rapid and reliable procedure for evaluating the arterial and venous changes due to tumors in the head and neck region.

Angiography, Digital Subtraction↗
PubMed1992

MR angiography in children with cerebral neurovascular diseases: findings in 31 cases.

OBJECTIVE: We evaluated the suitability of MR angiography for routine use in children with suspected intracranial vascular disease. SUBJECTS AND METHODS: Thirty-one children, 6 months to 14 years old, with intracranial lesions or clinically suspected vascular malformations were studied prospectively with conventional MR imaging and time-of-flight MR angiography. In nine cases, MR angiographic findings were verified with digital subtraction angiography or conventional angiography. All MR studies were performed on a 1.5-T MR system using a circularly polarized head coil. RESULTS: Arterial MR angiography, performed in 24 cases, revealed congenital abnormalities of the arterial vessels in 20 cases. Vessel stenosis was observed in nine patients, and displacement of intracranial arteries due to tumors could be seen in 10 patients. Seven children had no abnormal findings. Venous MR angiography was performed in seven children, with depiction of sinus thrombosis in six cases. The comparative analysis of MR angiography and digital subtraction angiography showed equivalent results in nine patients; in one patient the degree of stenosis was overestimated with MR angiography. CONCLUSION: MR angiography, when combined with MR imaging, reveals information about soft-tissue and vascular structures in a single setting. At this point, MR angiography can replace invasive conventional angiography or digital subtraction angiography only in selected cases because of software and hardware limitations. Arterial or venous MR angiography can be helpful as an additional scan in MR examinations of children with suspected cerebral neurovascular diseases, and its noninvasive nature makes it well suited for routine use in children.

Adolescent↗