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Biomedical subjects

Christoph L Zollikofer

Publications and source records attributed to Christoph L Zollikofer.

9 recordsLinked to original sources
PubMed2006

Gradient-enhanced volume rendering: an image processing strategy to facilitate whole small bowel imaging with MRI.

MRI of the small bowel with positive contrast from orally administered contrast agent is a promising non-invasive imaging method. The aim of our study was to introduce small bowel MRI in a display format that clinicians are accustomed to and that maximizes the amount of information visualized on a single image. Twelve healthy volunteers, median age 32 years (range 18-49 years) participated in the study. A mixture of 20 ml Gd-DOTA (Dotarem), 0.8 g/kg body weight psyllium fibre (Metamucil) and 1.2 l water were sequentially administered over a period of 4 h. Imaging was performed on a 1.5 T unit (Philips Gyroscan, Intera). Fat-saturated, 3D, gradient echo imaging was performed while the patient was in apnea (30 s). Bowel motion was reduced with 40 mg intravenously administered scopolamine (Buscopan). A 3D, gradient-enhanced, volume rendering technique was applied to the 3D data sets. Standard projections [left anterior oblique (LAO), right anterior oblique (RAO), supine and prone] resembling conventional enteroclysis were successfully generated within fewer than 10 min processing time. Reconstructions were reproducible and provided an entire overview of the small bowel. In addition thin-slab volume rendering allowed an overlap-free display of individual structures. Positive contrast from orally administered contrast agent, combined with a gradient enhanced volume rendering method, allows the reconstruction of the small bowel in a pattern resembling conventional double-contrast enteroclysis. Segmental display without overlay is possible.

Adolescent↗
PubMed2005

Small bowel motility assessment with magnetic resonance imaging.

PURPOSE: To assess primarily the feasibility of magnetic resonance imaging (MRI) as a tool to monitor small bowel peristaltic motion and secondarily to validate this technique by demonstrating drug-induced motility changes. MATERIALS AND METHODS: After a standardized oral preparation of Ispaghula husk (Metamucil) and meglumine gadoterate (Gd-DOTA; Dotarem), 10 volunteers underwent dynamic MRI using a two-dimensional turbofast field echo (TFE) sequence with a slice repetition time of 500 msec. Intraluminal cross-sectional caliber changes over time were assessed allowing quantification of the peristaltic frequencies and amplitudes of the small gut on various regions of interest. Pharmacologically induced alterations of the peristaltic motion after spasmolytics and gastrokinetic motion enhancers were investigated. RESULTS: Small bowel diameter measurement resulted in a peristalsis of 10.96 (SD = +/-2.51) waves per minute, oscillating regularly with mean amplitudes of 6.65 mm (SD = +/-1.15 mm). Peristaltic frequency in normal individuals is consistent with that observed with other techniques. Intravenous administration of scopolamine butylbromide (= hyoscine butylbromide/Buscopan) resulted in small bowel paralysis within 21.3 seconds (SD = +/-2.8 seconds). Prokinetic effect of intravenous metoclopramide (Paspertin) after Buscopan paralysis was tested in one volunteer, characterized by a slow recovery of peristalsis, which propagated from the proximal to the distal segments and enhanced contraction amplitudes. CONCLUSION: Dynamic MRI allows observing and quantifying small bowel peristalsis, characterizing motion patterns, and monitoring the effects of interfering factors such as drugs.

Adolescent↗
PubMed2004

First report of an accessory popliteal muscle: detection with MRI.

During an MRI examination of the knee in a 48-year-old patient suffering from degenerative changes of a partly resected medial meniscus and concomitant osteoarthritis of the knee joint, an unusual variant of an accessory muscle in the popliteal fossa was found. To our best knowledge this muscle has never been described before. Because of the close relationship to the popliteal muscle with regard to course and localisation in the deep popliteal fossa ventral to the popliteal artery, the term "accessory popliteal muscle" is proposed.

Diagnosis, Differential↗
PubMed2004

Primary cerebral leiomyosarcoma in a child.

We present a 13-year-old boy with a low-grade primary intra-axial cerebral leiomyosarcoma. MRI showed a contrast-enhancing intra-axial mass with features of a cell-rich tumour. The diagnosis was established after neurosurgery and exclusion of an extracerebral primary tumour. The resection of local recurrence 6 months later confirmed the diagnosis, but a higher grade of malignancy was established. The patient died 15 months after the onset of symptoms from general intracranial and intraspinal spread.

Adolescent↗
PubMed2003

High-resolution magnetic resonance angiography of hands with timed arterial compression (tac-MRA).

Timed arterial compression (tac) of blood flow can be achieved by inflation of a blood-pressure cuff. We postulated that this technique might improve contrast-enhanced magnetic resonance angiography (MRA) of the arteries of the hands. We studied eight volunteers and six patients with occlusive arterial disease of the hands with standard MRA and tac-MRA. Compared with standard MRA, acquisition time was extended with the blood-pressure cuff by a factor of four, leading to quadrupled image resolution (512x1024). Furthermore, flow-related artifacts were not seen. Tac-MRA permits visualisation of the peripheral arterial system in finer detail than that achieved with standard MRA.

Adult↗
PubMed2002

Giant cardiac myxoma with malignant transformed glandular structures.

A case of a right-sided giant cardiac myxoma with malignant transformation of glandular structures causing systemic metastases is described. Plain chest radiography and computed tomography localized the tumor within the heart. Exact depiction of the origin of the tumor using subtracted 2D-projection MR angiography is documented. Radiologic findings and differential diagnosis of this unique tumor are discussed.

Cell Transformation, Neoplastic↗
PubMedDate not supplied

Recanalization of acute and subacute femoropopliteal artery occlusions with the rotarex catheter: one year follow-up, single center experience.

PURPOSE: To assess the efficacy and safety of a new rotational catheter for percutaneous removal of fresh and organized thrombi in the femoropopliteal artery. METHODS: Forty-one limbs in 38 patients (age 56--90 years, mean 75.6 years) with acute, subacute or chronic femoropopliteal occlusions of 1--180 days' duration (mean 31.6 days) were treated with the Rotarex device. The Fontaine stage was mainly IIB (Rutherford 2--3, 22 patients) or III (Rutherford 4, 14 patients). The length of occlusion varied from 2 to 35 cm (mean 13.1 cm). After recanalization percutaneous transluminal angioplasty (PTA) was performed if there was a residual stenosis of >25%. Patients were followed up with color Doppler ultrasound at 48 hr and clinically with Doppler pressures and oscillometry at 3, 6, and 12 months. RESULTS: After an average of two passages with the Rotarex catheter all but two limbs required PTA for residual stenosis >25%. Five patients needed additional stenting. Major complications were one groin hematoma requiring blood transfusion and one arteriovenous fistula spontaneously thrombosing after unsuccessful primary prolonged balloon dilation. Distal embolizations occurred in 10 patients; 6 clinically relevant emboli were aspirated. All occlusions were technically successfully recanalised there were 2 early reocclusions after 1 day and two at 2 weeks. Brachial-ankle indices improved from an average of 0.41 before to 0.93 after recanalization. Primary and secondary patency rates were 62% / 84% after 6 months and 39% / 68% after 1 year. The amputation-free survival at 12 months was 100%. CONCLUSION: The Rotarex mechanical thrombectomy device is an efficient, quick, easy to handle, and safe tool for the treatment of acute, subacute or even chronic peripheral arterial thromboembolic occlusions. It can be used for short or long occlusions with equal success, provided the obstruction is not heavily calcified and has been safely passed with a guidewire first.

Acute Disease↗
PubMedDate not supplied

Colorectal stenting: an effective therapy for preoperative and palliative treatment.

PURPOSE: To demonstrate the effectiveness of preoperative and palliative colorectal stent placement in acute colonic obstruction. METHODS: Sixty-seven consecutive patients (mean age 67.3 years, range 25-93 years) with clinical and radiological signs of colonic obstruction were treated: 45 (67%) preoperatively and 22 (33%) with a palliative intent. In 59 patients (88%) the obstruction was malignant, while in 8 (12%) it was benign. A total of 73 enteric Wallstents were implanted under combined fluoroscopic/endoscopic guidance. RESULTS: Forty-five patients were treated preoperatively with a technical success rate of 84%, a clinical success rate of 83%, and a complication rate of 16%. Of the 38 patients who were successfully stented preoperatively, 36 (95%) underwent surgery 2-22 days (mean 7.2 days) after stent insertion. The improved general condition and adequate bowel cleansing allowed single-stage tumor resection and primary end-to-end anastomosis without complications in 31 cases (86% of all operations), while only 5 patients had colostomies. Stent placement was used as the final palliative treatment in 22 patients. The technical success rate was 95%, the clinical success rate 72%, and the complication rate relatively high at 67%, caused by reocclusion in most cases. After noninvasive secondary interventions (e.g., tube placement, second stenting, balloon dilatation) the secondary patency of stents was 71% and mean reported survival time after stent insertion was 92 days (range 10-285 days). CONCLUSION: Preoperative stent placement in acute colonic obstruction is minimally invasive and allows an elective one-stage surgery in most cases. Stent placement also proved a valuable alternative to avoid colostomy in palliation.

Adult↗