Biomedical subjects

Thomas Egelhof

Publications and source records attributed to Thomas Egelhof.

8 recordsLinked to original sources

PubMed2004

Unknown primary tumors: detection with dual-modality PET/CT--initial experience.

PURPOSE: To retrospectively evaluate fused positron emission tomography (PET)/computed tomography (CT) in depicting the primary lesion in cancer of an unknown primary tumor, compared with PET, CT, and PET and CT side-by-side evaluation. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Forty-five patients (26 men and 19 women) with metastatic cervical adenopathy (n = 18) or extracervical metastases (n = 27) of unknown primary tumor were included. The mean age of the patients was 57 years (range, 29-95 years). PET/CT imaging was performed in all patients 1 hour after administration of 350 MBq of fluorodeoxyglucose with a whole-body field of view. Contrast agents were administered orally and intravenously in all patients to ensure diagnostic CT data. PET/CT data sets were evaluated for the primary tumor, and imaging results were compared with those of CT, PET, and PET and CT side-by-side evaluation. Differences in diagnostic performance were assessed by using the McNemar test with Bonferroni correction, which accounts for multiple comparisons. RESULTS: PET/CT depicted the primary tumor in 15 (33%) of 45 patients. In 30 (67%) patients, the primary tumor site remained occult (P > .05). PET and CT side-by-side evaluation depicted 13 (29%) of 45 tumors (P > .05). PET alone revealed the primary tumor in 11 (24%) of 45 patients (P > .05), while CT alone helped in the correct diagnosis in eight (18%) of 45 patients (P > .05). There were no significant differences between the diagnostic accuracies of PET/CT and the other imaging modalities. CONCLUSION: PET/CT was able to depict more primary tumors, though not significantly, than either of the other imaging modalities, but larger patient cohorts are required to finally judge its value for revealing the primary tumor site.

Adult↗

PubMed2004

Albumin targeting of damaged muscle fibres in the mdx mouse can be monitored by MRI.

Increased sarcolemmal permeability has been implicated as a major pathological event in muscular dystrophies. In our study, we evaluated whether damaged muscle fibres can be specifically targeted using albumin as a carrier. We tagged human serum albumin (HSA) with Gadolinium (Gd) and systemically applied this compound (Gd-DTPA-HSA) to wildtype and dystrophin-deficient mdx mice. We performed magnetic resonance imaging before and after intravenous administration of Gd-DTPA-HSA and found localised signal enhancement only in mdx skeletal muscle. We also examined skeletal muscle after contrast enhanced magnetic resonance imaging using anti-human albumin antibodies and demonstrated intracellular accumulation of Gd-DTPA-HSA in clusters of damaged mdx muscle fibres. Comparison of magnetic resonance imaging and histological data emphasised the value of contrast agent enhanced magnetic resonance imaging for the in vivo assessment of fibre damage in muscular dystrophies. Furthermore, our data provide evidence that albumin can be used as a carrier to target covalently bound molecules to degenerating muscle fibres.

Animals↗

PubMed2004

Double-stent method: therapeutic alternative for small wide-necked aneurysms. Technical note.

The authors present two cases of patients with small, acutely ruptured, wide-necked aneurysms of the distal vertebral artery that were not amenable to conventional coil embolization and were instead treated by means of a double-stent method in which one stent was placed inside another. Angiography performed immediately after the procedure revealed a significant reduction in aneurysm filling; total occlusion of the lesion was observed after 7 days and confirmed 6 months later in both aneurysms. By placing one stent inside the other, stent permeability can be reduced, which may result in significant hemodynamic changes with accelerated aneurysm thrombosis. This double-stent method may represent a therapeutic alternative, especially in cases of small, wide-necked aneurysms in which conventional endovascular techniques or stent-supported coil embolization is not considered feasible or is believed to be too dangerous, and surgical treatment is contra-indicated.

Cerebral Angiography↗

PubMed2004

Acquisition protocol considerations for combined PET/CT imaging.

UNLABELLED: Since its introduction in 1998, dual-modality PET/CT imaging has received great attention in the medical community. For the first time, patients can be examined with both CT and PET in a single examination. A whole-body survey is the standard mode of acquisition. The CT images are used for anatomic reference of the tracer uptake patterns imaged in PET, as well as for attenuation correction of the PET data. The routine use of CT-based attenuation correction and user preferences for the quality and type of the CT examination have led to the introduction of different PET/CT scanning protocols. DISCUSSION: Two general approaches to PET/CT imaging can be distinguished today. One uses CT as a fast transmission source with little additional information for anatomic labeling. The other uses CT as a fast transmission source as well as a state-of-the-art diagnostic tool to maximize image quality using optimal acquisition parameters together with oral and intravenous contrast agents. Variations of these approaches share common concerns about image artifacts that result from mismatches in respiration and patient positioning between the CT and the PET examinations. Protocol requirements for the more complex radiologic PET/CT scenario also include alternative contrast application schemes or modifications to the attenuation correction procedure to handle CT contrast agents appropriately. CONCLUSION: High-quality PET/CT studies can be provided routinely with existing PET/CT technology that is used efficiently by trained and motivated technologists and physicians. Only then will the potential diagnostic benefit of this new imaging modality be explored fully.

Artifacts↗

PubMed2003

Symptomatic migraine and sensitization of trigeminal nociception associated with contralateral pontine cavernoma.

A 38-year-old woman is described with symptomatic strictly right-sided migraine associated with a pontine cavernoma affecting the contralateral (left) nucleus raphe magnus. A persistent facilitation of the right-sided trigeminal nociception was detected interictally using the 'nociception specific' blink reflex, which was more pronounced during the acute attack. This case shows for the first time, an impairment of the anti-nociceptive brainstem nuclei and the facilitation of the trigeminal nociception in the same subject, thus providing further evidence for the key role of the brainstem raphe nuclei in the pathophysiology of migraine.

Adult↗

PubMed2002

Endovascular treatment of unruptured intracranial aneurysms.

BACKGROUND AND PURPOSE: Intracranial aneurysms are common, with an overall frequency ranging from 0.8% to 10%. Because prognosis after subarachnoid hemorrhage is still very poor, treatment of unruptured aneurysms, either neurosurgically or endovascularly, has been advocated. However, risk of rupture and subsequent subarachnoid hemorrhage needs to be considered against the risks of elective treatment. We analyzed the technical feasibility, safety, and efficacy of endovascular treatment of a consecutive series of unruptured cerebral aneurysms. METHODS: From July 1997 through December 2000, a total of 76 patients with 82 unruptured cerebral aneurysms were treated at our institution. Endovascular treatment was administered to 39 consecutive patients with a total of 42 unruptured cerebral aneurysms. Thirty-six aneurysms were treated with an endovascular technique; in six patients, the parent artery was occluded to eliminate aneurysmal perfusion. Aneurysms were located either in the anterior (n = 31) or posterior (n = 11) circulation. Eight patients had experienced previous subarachnoid hemorrhage from other aneurysms and were treated electively after complete rehabilitation. Ten patients had neurologic symptoms; in 21 patients, the aneurysm was an incidental finding. Eighteen aneurysms were small (0-5 mm), 11 were medium (6-10 mm), nine were large (11-25 mm), and four were giant (> 25 mm). Occlusion rate was categorized as complete (100%), subtotal (95-99%), and incomplete (< 95%) obliteration. RESULTS: Endovascular treatment was technically feasible for 38 of 42 aneurysms. Complete (100%) or nearly complete (95-99%) occlusion was achieved in 34 of 38 aneurysms. In four aneurysms of the internal carotid artery, only incomplete (< 95%) occlusion was achieved. All patients except one with mild neurologic deficits according to the Glasgow Outcome Scale and one with mild memory dysfunction but no focal neurologic deficit achieved good recovery, resulting in a morbidity rate of 4.8% and a mortality rate of 0%. CONCLUSION: Endovascular embolization of unruptured cerebral aneurysms is an effective therapeutic alternative to neurosurgical clipping and is associated with low morbidity and mortality rates. For the management of unruptured aneurysms, endovascular treatment should be considered.

Adult↗

PubMed2002

Focal tracer uptake: a potential artifact in contrast-enhanced dual-modality PET/CT scans.

UNLABELLED: This study was performed to evaluate a possible artifact related to the administration of intravascular contrast agent in dual-modality PET/CT imaging. METHODS: Thirty oncology patients underwent whole-body PET/CT. CT images, which were collected in the presence of intravenous and oral iodinated contrast agent, were used for PET attenuation correction. PET images were assessed for the artifact, defined as a region of high count rate on attenuation-corrected images in accurate coregistration with a contrast-enhanced blood vessel. Intravascular enhancement of thoracic veins was quantified by application of regions of interest, and quantities in patients with the artifact (group 1) and without the artifact (group 2) were correlated. Body surface area was calculated for all patients. RESULTS: The contrast-induced PET artifact was present in 4 (13%) of 30 patients. Mean density differences in intravascular enhancement were highly significant (P < 0.001) in a comparison of group 1 (2,262 +/- 304 Hounsfield units [HU]) and group 2 (1,058 +/- 209 HU). Body surface area was significantly lower (P = 0.035) in the patients of group 1 (1.67 +/- 0.11 m(2)) than in the patients of group 2 (2.01 +/- 0.18 m(2)). CONCLUSION: Contrast-enhanced dual-modality PET/CT examinations may result in a PET artifact that is due to the transient bolus passage of undiluted intravenous contrast agent.

Artifacts↗

PubMedDate not supplied

Dual modality of 18F-fluorodeoxyglucose-positron emission tomography/computed tomography in patients with cervical carcinoma of unknown primary.

OBJECTIVE: To evaluate an optimized F-18-flurodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) acquisition protocol for head and neck cancer and assess the usefulness of combined FDG-PET/CT in locating unknown primary tumors in patients with biopsy-proven cervical lymph node metastases. SUBJECTS AND METHODS: Twenty-one patients with cervical lymph node metastases of unknown primary tumors underwent staging with FDG-PET/CT. The images of FDG-PET alone, CT alone, FDG-PET/CT read side by side and fused and FDG-PET/CT were evaluated separately by 2 physicians. Imaging results were correlated with either histology (n = 14) or clinical follow-up (n = 7). RESULTS: On the fused FDG-PET/CT images, primary tumors were identified in 12 patients (57%); with FDG-PET alone and FDG-PET and CT read side by side 11 (52%) primary tumors were found while CT alone identified 5 (23%) primary tumors. CONCLUSION: Our data indicate that fused FDG-PET and CT images increased the sensitivity of detecting carcinoma of unknown primary (CUP) tumors compared to CT alone, but not to FDG-PET alone or FDG-PET and CT read side by side. Hence accurate fusion of functional and morphologic data by FDG-PET/CT is a promising imaging modality in the clinical workup of patients with cervical CUP tumors.

Aged↗