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Biomedical subjects

K D Mathias

Publications and source records attributed to K D Mathias.

At least 19 recordsLinked to original sources
PubMed2001

[Cerebral protection with balloon occlusion during carotid artery stent implantation--first experiences].

PURPOSE: To assess the technical feasibility and the results of cerebral protection with the GuardWire Plus Temporary Occlusion & Aspiration System during carotid artery stenting for high-grade stenosis. PATIENTS AND METHODS: In 20 patients 20 carotid artery stenoses were treated with stent placement under cerebral protection. A contralateral carotid occlusion was an exclusion criteria for the use of the protection device. In all cases only aspiration, but no flushing was used before deflation of the occlusion balloon. In 17 of 20 patients diffusion-weighted (DW-)MRT imaging of the brain was performed before and 24 hours after the procedure. RESULTS: The stent implantation was successfully performed in all patients. In 3 patients neurologic symptoms occurred during the occlusion time. In these 3 patients the symptoms immediately disappeared after deflation of the balloon. In one case there was dilatation of the internal carotid artery at the site of the balloon inflation. In 3 of the 17 DW-MR images new ipsilateral cerebral lesions, in one case a new contralateral lesion occurred after the procedure. CONCLUSIONS: The cerebral protection procedure is technically feasible. The occlusion of the internal carotid artery was not tolerated by all patients. The DW-MR imaging demonstrated cerebral lesions indicating the occurrence of cerebral microemboli during the procedure. Further investigations are necessary to determine if the use of the cerebral protection device will improve the results of the carotid artery stenting for high-grade stenoses.

Aged↗
PubMed2001

Diffusion-weighted MR imaging after angioplasty or angioplasty plus stenting of arteries supplying the brain.

BACKGROUND AND PURPOSE: There has been concern regarding the safety of revascularization procedures of vessels supplying the brain vessels because of the risk of cerebral embolization during the procedure. We have observed a high incidence of hyperintense lesions on diffusion-weighted MR images of the brain after stenting at the carotid bifurcation. The hypothesis of this study is that diffusion-weighted MR imaging of the brain can reveal new diffusion abnormalities after angioplasty or angioplasty plus stenting of arteries supplying the brain, other than at the carotid bifurcation. Therefore, we prospectively obtained diffusion-weighted MR images of the brain before and after such revascularization procedures. METHODS: Thirty-seven revascularization procedures were performed in 32 patients. Eleven interventions were performed at the distal internal carotid artery, two at the external carotid artery, two at the common carotid artery, five at the innominate artery, five at the vertebral artery, and 12 at the proximal subclavian artery. Diffusion-weighted MR imaging of the brain was performed before and 24 hours after the procedures. RESULTS: After eight (22%) of 37 procedures, new hyperintensities were visible on the diffusion-weighted MR images. With six of these eight procedures, the hyperintensities occurred in the vascular territory supplied by the treated vessel. In total, 35 new cerebral lesions could be seen, 33 (94%) of which occurred in the vascular territory supplied by the treated vessel. None of the patients in whom new diffusion abnormalities were found had new neurologic symptoms or deficits. No new lesions could be seen after procedures at the subclavian artery. CONCLUSION: Revascularization procedures of arteries supplying the brain were associated with new lesions on the diffusion-weighted MR images of the brain after 22% of the procedures, provided that MR imaging could be performed, indicating the occurrence of cerebral microemboli during such procedures. Diffusion-weighted MR imaging of the brain can be used as a tool to assess the impact of modifications of procedural technique and/or the use of cerebral protection devices on the occurrence of such lesions.

Adult↗
PubMed2000

Congenital absence of the internal carotid artery and the basilar artery with persistent trigeminal artery associated with coarctation of the aorta.

We report a case of congenital absence of the cervical and petrous part of the left internal carotid artery, the middle and proximal part of the basilar artery, and the V4 segment of the left vertebral artery associated with a left persistent trigeminal artery and a coarctation of the aorta. The left cerebral vessels are supplied via the anterior communicating artery and the left persistent trigeminal artery. The coexisting coarctation of the aorta led to a subclavian steal phenomenon. The alteration of the cerebral hemodynamics has to be taken in consideration when performing cerebral angiography and surgical correction in such a case.

Adult↗
PubMed2000

[Results of stereotactic breast biopsy in mammographically suspicious lesions].

PURPOSE: The object of this study was to evaluate the diagnostic accuracy of the stereotactic large core breast biopsy in the histological assessment of mammographically suspicious lesions. MATERIAL AND METHODS: In 106 patients with a mammographically suspicious lesion, 67 with a mass (55 non-palpable, 12 palpable and 39 with microcalcification stereotactic large core biopsies were performed. Samples were obtained in the prone position under local anesthesia with a 14-gauge needle and an automated high-speed gun. An average of 4.3 cores per lesion were acquired. In 68 patients (64%) an additional surgical biopsy was performed, 38 (36%) had clinical and mammographic follow-up. RESULTS: In 4 of the 106 stereotactic biopsies insufficient material for the histological examination was obtained. In the 68 core biopsies with surgical correlation there were no false-positive, but 2 false-negative results with regard to the malignancy of the lesion (sensitivity: 93.8%; specificity: 100%). The 2 false-negative results were obtained in lesions that were mammographically judged as malignant while histology of the stereotactic biopsy showed fibrosis. The stereotactic large core breast biopsy was well tolerated by all patients. No clinically significant complications occurred. CONCLUSION: The stereotactic large core breast biopsy of a mammographically suspicious lesion can be performed with a high diagnostic accuracy. A correlation of the mammographic and histological findings and a follow-up program are necessary in order to recognize false-negative results early and to avoid a delay in the diagnosis.

Adult↗
PubMed1999

Rectum and sigmoid colon necrosis due to cholesterol embolization after implantation of an aortic stent-graft.

Endovascular treatment of abdominal aortic aneurysms (AAAs) with stent-grafts is increasingly performed. Recent studies have shown that stent-graft placement for AAA is technically feasible and can effectively exclude aneurysms from the circulation. However, complications related to the procedure, such as graft thrombosis, migration of the prosthesis, peripheral embolization, and leaks with incomplete exclusion of the aneurysmal sac, have been reported. We report a case of rectum and sigmoid colon necrosis with fatal outcome due to cholesterol embolization after implantation of a stent-graft for an infrarenal AAA.

Aortic Aneurysm, Abdominal↗
PubMed1997

Degenerative change in the cervical spine and load-carrying on the head.

OBJECTIVE: To evaluate the relationship between load-carrying on the head and the development of degenerative change in the cervical spine. DESIGN AND SUBJECTS: A case-control study was performed with 35 individuals who had carried loads on their head (carriers) and 35 persons who never had carrier loads on their head (non-carriers). A scoring system was utilized for the assessment of the degenerative change in the cervical spine at the C3/C4, C4/C5, C5/C6 and C6/C7 levels on lateral cervical spine radiography. A total score was calculated by summing the scores for the single segments. RESULTS AND CONCLUSION: In 31 of the 35 (88.6%) carriers degenerative change was found in the cervical spine, but only in 8 of the 35 (22.9%) non-carriers (P < 0.01). The total score and the scores for segments C4/5, C5/C6 anc C6/C7 were significantly higher for the carriers than the non-carriers. It is concluded that the axial strain of load-carrying on the head exacerbates degenerative change in the cervical spine.

Adult↗
PubMed1997

Cervical diastematomyelia and syringohydromyelia in a myelomeningocele patient.

A case of cervical diastematomyelia and syringohydromyelia in a 16-year-old female myelomeningocele patient is reported. Progressive weakness of the upper extremity led to an MR examination of the brain and spine, which revealed hydrocephalus, Chiari II malformation, cervical diastematomyelia with a syringohydromyelic cavity in each hemicord and a large dural sac in the lumbar region. Operative therapy consisted of detethering and shunting of the two syringes. Soon after surgery her symptoms improved. The need for early complete MR imaging of myelomeningocele patients presenting with new symptoms is emphasized.

Adolescent↗
PubMed1997

Radiological features of the visceral and skeletal involvement of hemochromatosis.

Hemochromatosis is a multisystem disorder produced by the excessive accumulation of iron in visceral organs and the musculoskeletal system. Clinically the disease may be silent, but characteristic radiological features may point to the diagnosis. The increased iron stores in the organs involved, especially in the liver and pancreas, result in an increased attenuation at unenhanced CT and an decreased signal intensity at MR imaging. Hemochromatosis arthropathy includes degenerative osteoarthritis and chondrocalcinosis. The distribution of the arthropathy is distinctive, but not unique, frequently affecting the second and third metacarpophalangeal joints of the hand.

Adult↗
PubMed1997

A physiologic in vitro model of the inferior vena cava with a computer-controlled flow system for testing of inferior vena cava filters.

RATIONALE AND OBJECTIVES: The authors develop a physiologic in vitro model of the inferior vena cava (IVC) for testing of filters. METHODS: The model is driven by a centrifugal pump. A computer-controlled electromagnetic valve is used for generation of different flow patterns. Limitation of the pressure increase in case of IVC occlusion is achieved by a bypass circuit. A glycerin solution is used for perfusion. Artificial clots are made from polyacrylamide gel. Data acquisition includes continuous monitoring of flow and difference pressure over the filter and video recording of the testing events. RESULTS: The model can generate constant and pulsatile flows. The pressure increase can be limited to 70 mm Hg in case of occlusion. Calculation of the flow velocities in the IVC is possible. A classification of thrombus capturing is presented. The testing of most of the results are reproducible. CONCLUSIONS: The in vitro model simulates the physiologic conditions in the IVC. It can be used for comparative testing of different filters and the evaluation of new filter designs.

Blood Flow Velocity↗
PubMed1996

[Comparison of liver resection with sequential transarterial chemoembolization in stage pT3 or pT4 hepatocellular carcinoma].

Between January 1990 and January 1996, 39 consecutive patients with histologically improved pT3 or pT4 HCC tumors underwent curative resection (n = 19) or sequential transarterial chemoembolization (n = 20) with a median time interval of 7 weeks up to six times with an emulsion of Lipiodol, Epirubicin and Cisplatin. The 30-day mortality rate for all sessions of TA was 3.8% vs. 21.8% in the resection group (p < 0.05); the cumulative survival rate for the embolization group at 6, 12, 18 and 24 months was 72.3%, 50.1%, 41.2%, 35.4% vs. 42.1%, 31.6%, 31.6% and 14.2% following resection, which cannot be considered statistically significant. Patients with T3 and T4 HCC, treated with sequential embolization or resection, seem to have a comparable survival time.

Carcinoma, Hepatocellular↗
PubMed1995

[Invasion of the growth plate by bone tumors and osteomyelitis in childhood].

Crossing of the physis by primarily metaphyseal, localized bone tumors and osteomyelitis in childhood was rarely observed. Therefore, the physis in childhood is considered to be a barrier against the spread of tumors and infection. We report five children, in whom MR imaging demonstrated early crossing of the physis and spread of the disease from the metaphysis to the epiphysis. Follow-up in three children with osteomyelitis showed that antibiotic therapy resulted in almost complete resolution of the changes in the physis, epiphysis and metaphysis. These observations challenge the concept of the physis as a barrier against the spread of tumors and infection.

Arthritis, Infectious↗
PubMed1987

Aneurysm of the superior mesenteric vein.

A superior mesenteric vein aneurysm was diagnosed by ultrasound, computed tomography, and angiography in a 55-year-old woman. It was successfully treated by partial resection and reconstruction of the confluent veins.

Aneurysm↗
PubMed1976

[Changes of cutaneous blood flow after aortofemoral angiography (author's transl)].

Temperature versus time curves were registered during aortofemoral angiography in 48 patients. The cutaneous temperature was initially reduced in 46 of the patients. This phenomenon was interpreted as a temporary decrease of blood flow and can not be explained by hypertonicity of contrast media, but indicates additional pharmacodynamic effects. Reactive hyperemia depends on pathologic alterations of large and small vessels.

Contrast Media↗