Johann Link

Differentiation of cerebral tumors using multi-section echo planar MR perfusion imaging

OBJECTIVEnWe have investigated the performance of magnetic resonance (MR) perfusion imaging to differentiate between astrocytomas grade II, grade III and glioblastomas in a prospective study.nnnMATERIALS AND METHODSnIn 33 patients with suspected supratentorial primary cerebral tumors we performed multi-section Echo Planar MR perfusion imaging. Regional cerebral blood volume (rCBV) maps were calculated and the maximum rCBV was determined from the entire lesion. This value was divided by the mean rCBV value from the contralateral side, which provided the rCBV index used in this study. The rCBV index was correlated with the histological tumor classification after stereotactic biopsy (n=7) or open resection (n=26).nnnRESULTSnThe maximum rCBV index was 1.2+/-0.8 for grade II astrocytomas (n=3), 4.0+/-1.2 for grade III astrocytomas (n=13), and 10.3+/-3.3 for glioblastomas (n=17). The difference between grade III astrocytomas and glioblastomas was highly significant (P<0.001).nnnDISCUSSION AND CONCLUSIONnThe rCBV index measured with multi-section Echo Planar MR perfusion is capable of differentiating grade III astrocytomas from glioblastomas. It serves as an additional parameter to establish a diagnosis in cases where it is not possible to clearly differentiate between these types of tumors on the basis of conventional MR imaging. MR perfusion imaging also provides information about spatial heterogeneities within a tumor which might improve diagnostic performance. This technology may also be of interest for follow-up examinations after histological diagnosis and further treatment.

Rheolytic thrombectomy of an acutely thrombosed transjugular intrahepatic portosystemic stent shunt

As an alternative to chemical thrombolysis, an acutely occluded transjugular intrahepatic portosystemic stent shunt in a 72-year-old women was successfully recanalized using a 5 Fr rheolytic catheter system. No adjunctive thrombectomy treatment was necessary. The underlying stenotic leason was treated with percutaneous transluminal angioplasty and a Palmaz stent. Immediately after the intervention optimal shunt flow was achieved. Ascites vanished within a few days and no further bleeding complications appeared.

Perivascular inflammatory reaction after percutaneous placement of covered stents.

A 52-year-old woman with an extensive superficial femoral artery occlusion was treated with percutaneous transluminal angioplasty. Because of extensive dissections, two covered stents were placed percutaneously. The intervention was successful with respect to vessel patency, but local pain and fever developed 5 hr after the intervention. Swelling of the thigh occurred, but deep venous thrombosis was excluded. MRI revealed pronounced soft-tissue edema in the adductor canal that persisted for 4 weeks. The fever responded to antiin-flammatory medication, but the pain remained for 4 weeks. The vessel was patent at the last follow-up, 8 weeks after graft placement. Soft-tissue edema after percutaneous placement of covered stents has been reported previously. The cause of the inflammatory reaction is unclear.

Severe Hemoptysis Requiring Lobectomy in an 11-Year-Old Patient With Kartagener’s Syndrome

The case of a young girl with severe hemoptysis in a Kartageners syndrome is described. Because bronchoscopy failed to locate the origin of the bleeding, preoperative angiography was performed. The patient was treated by resection of the middle lobe. The bronchus wall was located as the origin of bleeding.

Effects of selective angiography of the carotid artery with carbon dioxide on electroencephalogram somatosensory evoked potentials and histopathologic findings. A pilot study in pigs.

RATIONALE AND OBJECTIVESnThe authors investigate the cerebral effects of selective carotid angiography with carbon dioxide (CO2).nnnMETHODSnIn 6 pigs, CO2 was injected into the carotid artery with consecutively increasing doses. Cerebral function was monitored with two-channel electroencephalography and somatosensory evoked potentials (SEPs). After the experiment the brains were investigated histopathologically.nnnRESULTSnInitial doses led to reversible decreases in electroencephalograph power by 40% to 80%. Further doses result in partly nonreversible electroencephalographic changes. Somatosensory evoked potential latencies (n = 5) were not changed. Amplitudes were not affected in low dose ranges up to 40 mL CO2. Higher CO2 doses led to different changes. There were no SEP amplitude reductions (n = 1), as well as reversible (n = 2) and nonreversible (n = 2) SEP amplitude reductions. Histopathologically, edema (n = 6), edema necrosis (n = 2), and destroyed cells as a sign of ischemia (n = 2) were found.nnnCONCLUSIONSnAdministering CO2 in brain supplying arteries impairs the cerebral function. Consecutive, increasing doses lead to partly nonreversible electroencephalographic and SEP changes and brain tissue damages.

Prospective assessment of carotid bifurcation disease with spiral CT angiography in surface shaded display (SSD)-technique

PURPOSEnTo decide, whether spiral CT-angiography (CTA) in surface display (SSD)-technique is suitable for accurate quantification of carotid artery stenoses.nnnMATERIAL AND METHODSnForty-four patients (25 male, 19 females) with a total of 80 symptomatic carotid artery were studied prospectively with selective cerebral angiography and spiral CTA in SSD-technique. The degree of stenosis was determined according to the NASCET-study.nnnRESULTSnAssessment of the degree of stenoses with CTA and angiography was the same in 36% of mild stenoses, in 64% of moderate stenoses, in 68% of severe stenoses, and in 95% of the occluded internal carotid arteries. Overall, CTA in SSD-technique showed equivalent results as selective cerebral angiography in 65% of all cases.nnnCONCLUSIONnSpiral CTA in SSD-technique is inferior to selective cerebral angiography. Calcified plaques, vessel opacification and thresholding influence the most grading of stenosis.

Influence of different fasting periods on P-31-MR-spectroscopy of the liver in normals and patients with liver metastases

The purpose of this study was to determine the influence of different fasting periods on the in vivo P-31-MR spectroscopy of the healthy liver and patients with liver metastases. Image-guided localized P-31-MRS was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. The P-31-MRS was performed after a fasting period of 3–5 h (group 1) and after overnight fasting (group 2). The PME/β-NTP, PDE/β-NTP and Pi/β-NTP were calculated from P-31-MR spectra and were compared in relation to the nutrition status of the volunteers and patients. The PME/β-NTP and PDE/β-NTP were significantly increased in spectra of patients with metastases. There were no significant changes in the ratios of phosphorus metabolites in healthy liver tissue or in liver metastases after a fasting period of 3–5 h as compared with overnight fasting.

Theoretical considerations and in vitro results for the development of percutaneous transcatheter balloon embolectomy.

RATIONALE AND OBJECTIVESTo prove the feasibility of performing percutaneous transcatheter embolectomy using a funnel-shaped catheter tip and balloon embolectomy catheters. METHODSA theoretical model is described to assess the influence of the diameter of an introductory device and coaxially introduced embolectomy catheter. A funnel-shaped catheter tip was attached to 7F, 8F, and 9F introductory sheaths. In vitro embolectomy of 5 g and 12 g thrombi was performed with 3F and 4F embolectomy catheters. RESULTSThe number of extractions required was significantly related to the ratio of the diameters of the sheaths and embolectomy catheter shafts. The combination of a 7F sheath with a 4F embolectomy catheter required the greatest number of extractions (8.4 ± 1.7). The least number of extractions was needed for the combination of a 9F sheath with 4F and 3F embolectomy catheters (1.6 ± 0.7 and 1.8 ± 0.4, respectively). CONCLUSIONSOur results indicate that percutaneous embolectomy with balloon embolectomy catheters is feasible. However, further research is necessary before the final catheter design is chosen.

THE TOTAL ENTROPY FOR EVALUATING 31P-MAGNETIC RESONANCE SPECTRA OF THE LIVER IN HEALTHY VOLUNTEERS AND PATIENTS WITH METASTASES

RATIONALE AND OBJECTIVESnThe authors describe the clinical status of liver tissue with only a single numerical quantity (total entropy) derived from spectroscopic data of 31P-magnetic resonance (MR) spectra.nnnMETHODSnTwenty-four patients with liver metastases and 20 volunteers were investigated with image-guided volume selective 31P-MR spectroscopy on a 1.5-T whole body scanner. From each in vivo 31P-MR spectrum, the ratios of phosphomonoester (PME)/beta-adenosine triphosphate (ATP), inorganic phosphate (Pi)/beta-ATP and phosphodiester (PDE)/ beta-ATP and the total entropy (H*) were calculated. Mean values and standard deviations were determined and significance of the differences were tested with Students t test.nnnRESULTSnFor patients, the H* = 4.7 +/- 4.3, PME/beta-ATP 0.72 +/- 0.28, Pi/beta-ATP = 1.00 +/- 0.39, PDE/beta-ATP = 1.68 +/- 0.59. For the volunteers, H* = 7.6 +/- 2.5, PME/beta-ATP = 0.39 +/- 0.15, Pi/beta-ATP = 0.90 +/- 0.19, PDE/beta-ATP = 1.25 +/- 0.28. The total entropy of patients spectra showed significantly lower values compared with those of volunteers. PME/beta-ATP and PDE/beta-ATP of the patients increased and differed significantly from volunteer data.nnnCONCLUSIONSnIt was demonstrated that the results of in vivo 31P-MR spectroscopy may be described with a single criterion by means of the total entropy.

MR Angiography of the iliofemoral artery system

SummaryDuring the last years, magnetic resonance angiography (MRA) has become a widely used modality for intracerebral and carotid artery imaging. Due to technical limitations, the clinical impact of MRA in the iliofemoral arteries has been rather poor. New developments in MRA like ECG-triggered sequences and the occurrence of contrast-enhanced MRA has overcome most of these limitations. Therefore, a major advance in clinical use of these diagnostic tools can be predicted. This paper discussed the advantages of ECG-gated 2D-Phase contrast, ECG-gated 2D-Time-of-Flight and contrast enhanced FLASH 3D angiography sequences from a clinical point of view. 2D-PC-MRA is a robust technique, which provides an overview of the iliofemoral artery system in less than 5 minutes. Limitations are the true 2D impression of the sequence and the partial venous overlay. 2D-TOF-MRA on the other hand is time consuming, however it enables 3D reconstruction and effective venous suppression can be applied. Contrast enhanced MRA as the third sequence discussed provides high resolution images in less than 30 sec. However contrast bolus timing might be a problem. In conclusion the authors suggest a combination of 2D-PC-MRA and additional 2D-TOF sequences at questionable vacular areas as the modality of choice, due to the fact, that MRA of the iliofemoral arteries ist mostly only one step of a complete lower limb examination. Contrast MRA might become the method of choice in the future however problems with multiple contrast injections and upper limits of contrast dose have to be solved.ZusammenfassungWährend der letzten Jahre ist die Magnetresonanzangiographie (MRA) zu einer wertvollen klinischen Methode in der Diagnostik von krankhaften Prozessen der supraaortalen und der intrazerebralen Arterien geworden. Aufgrund technischer Limitationen wird sie jedoch im Körperstamm und insbesondere im Beckenbereich eher selten eingesetzt. Neue Entwicklungen wie die Einführung getriggerter Sequenzen oder der kontrastmittelunterstützten Verfahren machen jedoch eine Neubewertung des Verfahrens notwendig. Eine zunehmende Verbreitung des Verfahrens erscheint im Bereich der Beckenetage gerechtfertigt. Die vorliegende Arbeit stellt verschiedene Ansätze in der MRA vor, insbesondere werden Studien mit den Methoden der 2D-Phasenkontrast-MRA, der 2D-Time-of-flight-MRA und der kontrastmittelunterstützten MRA beschrieben. Die 2D-PC-MRA ist ein robustes Verfahren, welches einen Überblick über die Beckengefäße mit einer Untersuchungszeit von weniger als 10 min liefert. Limitationen sind hier die Zweidimensionalität des Verfahrens. Die 2D-TOF-MRA hat den Nachteil eines höheren Zeitaufwandes von 15–20 min, bietet jedoch den Vorteil der dreidimensionalen Rekonstruktion und der besseren venösen Absättigung. Die kontrastmittelverstärkte MRA ermöglicht hochaufgelöste Bilder mit Aufnahmezeiten von 25–90 s, abhängig von der gewählten Sequenz. Aufgrund der Erfahrungen in unserer Klinik empfehlen wir eine Kombination aus 2D-PC-MRA und 2D-TOF-MRA für die Diagnostik der Beckengefäße. In naher Zukunft könnte jedoch die kontrastmittelunterstützte MRA die Methode der Wahl sein.