The spectrum of clinical signs in cases of superior sagittal sinus thrombosis includes not only focal neurological deficits, seizures and mental disturbances, but also symptoms which may lead to a diagnosis of pseudotumour cerebri (PTC). In 14 cases of angiographically (or autopsy) proven thrombosis of the superior sagittal or both lateral sinuses, the "empty triangle" sign on contrast CT examination was the most reliable sign, suggesting the diagnosis in 70%. Indirect CT signs (venous infarcts) were observed in all 8 patients with focal neurological signs, but appeared rather delayed in 3 cases. In contrast, patients with "benign" intracranial hypertension or PTC (6 cases) had normal unenhanced scans (4 cases) or showed slight diffuse brain oedema (2 cases). Magnetic resonance imaging was performed in 4 patients with findings suggestive of intravascular coagulation; however, due to the complexity of flow phenomena, further studies employing this new imaging technique will first have to be performed. Thus, angiography remains the best diagnostic tool and should not be delayed if there is a clinical suspicion of thrombosis.
Pseudotumor cerebri (PTC) is a diagnosis per exclusionem applied to a condition of increased intracranial pressure in the absence of an intracranial infection, a space-occupying lesion, or hydrocephalus. Diagnostic criteria should include the evaluation of possibly disturbed cerebral venous outflow, which may result in similar clinical findings. Disturbed venous drainage should be separated from the syndrome of PTC because it represents a condition of well-defined origin and therapeutic regimen. Course and prognosis of PTC are not related to the increased intracranial pressure, the degree of papilledema, or to the duration of the disease. Functional cerebral disorders and EEG abnormalities are rare, indicating that brain tissue is not primarily affected. Correspondingly, computerized tomography (CT) scans with respect to the cerebrum are normal in about 90% of the cases; but enlarged optic nerve sheaths (46.7%) and empty sella (45.7%) are frequent findings on CT-scans. They most likely represent a direct consequence of long-term increased pressure within CSF spaces. This observation favors the assumption of disturbed CSF-pressure regulation either by increased production of CSF or its decreased rate of absorption. Brain edema (slit ventricles) as assessed by CT is a rare finding (11.4% of our cases). It may be a hint towards a different pathogenetic entity.
Objectives: Renal lesions are sometimes incidentally detected during computed tomography (CT) examinations in which an unenhanced series is not included, preventing the lesions from being fully characterized. The aim of this study was to investigate the feasibility to use virtual non-contrast (VNC) images, acquired using a detector based dual-energy CT, for the characterization of renal lesions. Methods: Twenty-seven patients (12 women) underwent a renal CT scan, including a non-contrast, an arterial and a venous Phase contrast-enhanced series, using a detector-based dual-energy CT scanner. VNC images were reconstructed from the venous contrast-enhanced series. The mean attenuation values of 65 renal lesions in both the VNC and true non-contrast (TNC) images were measured and compared quantitatively. Three radiologists blindly assessed all lesions using either VNC or TNC images in combination with contrast-enhanced images. Results: Sixteen patients had cystic lesions, five had angiomyolipoma (AML), and six had suspected renal cell carcinomas (RCC). Attenuation values in VNC and TNC images were strongly correlated (ρ = 0.7, mean difference −6.0 ± 13 HU). The largest differences were found for unenhanced high-attenuation lesions. Radiologists classified 86% of the lesions correctly using VNC images. Conclusions: In 70% of the patients, incidentally detected renal lesions could be accurately characterized using VNC images, resulting in less patient burden and a reduction in radiation exposure. Advances in knowledge: This study shows that renal lesions can be accurately characterized using VNC images acquired by detector-based dual-energy CT, which is in agreement with previous studies using dual-source and rapid X-ray tube potential switching technique.
Im gekoppelten 13C‐NMR‐Spektrum zeigt Triazolam (2) wie die N‐1‐substituierten 1,4‐Benzodiazepin‐2‐one für C‐3 ein Doppeldublett, während die Verbindungen 1,3,4 und 5 lediglich ein Triplett in diesem Bereich aufweisen. Für die Doppeldublettaufspaltungen (154 ± 2 und 133 ± 2Hz) kommen aufgrund von Temperaturmessungen und der Spin‐Gitter‐Relaxationszeiten T1 in Lösung nur die Konformationen Ia und/oder IIb in Frage. Dabei wird dem äquatorialen, aciden Proton, dessen Signal im 1H‐NMR‐Spektrum bei tieferem Feld erscheint, die größere Kopplungskonstante zugeordnet. Das Aufspaltungsmuster des Signals von C‐3 in den 1,5‐Benzodiazepin‐2,4‐dionen 6 und 7 ist lösungsmittelabhängig. Darüber hinaus wird die Konformation der Cyclopropylmethyl‐Seitenkette im Prazepam (12) festgelegt.
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