Ari Karttunen

A Comparison of Radiation Exposure between Diagnostic CTA and DSA Examinations of Cerebral and Cervicocerebral Vessels

This article compares radiation exposure from CTA and DSA used to evaluate the extra- and intracranial circulations. Experiments were performed on a phantom using a 64-section CT scanner and biplane DSA. The authors concluded that the effective dose for CTA assessment of cerebral vessels was approximately one-fifth the dose compared with DSA. In the imaging of cervicocerebral vessels, the effective dose for CTA was approximately one-third higher compared with DSA. BACKGROUND AND PURPOSE: While the number of CTA examinations is continually increasing compared with DSA examinations, there is little comparative dose information about the different imaging techniques. We compared patient radiation exposure resulting from diagnostic CTA and DSA examinations for both cerebral and cervicocerebral vessels. MATERIALS AND METHODS: An anthropomorphic phantom was irradiated by using typical diagnostic CTA and DSA setups and imaging parameters. For both imaging techniques, the imaging area of cerebral vessels included intracranial vessels only, while the imaging area of cervicocerebral vessels included both cervical and intracranial vessels from the aortic arch to the vertex. The effective dose was determined by using RPLDs. The DSA examination was simulated by using a biplane angiography system, and the CTA examination, by using a 64-row multidetector CT scanner. RESULTS: For the imaging of cerebral vessels, the effective dose according to ICRP 103 was 0.67 mSv for CTA and 2.71 mSv for DSA. For the imaging of cervicocerebral vessels, the effective dose was 4.85 mSv for CTA and 3.60 mSv for DSA. The maximum absorbed dose (milligray) for skin, brain, salivary glands, and eyes was 166.2, 73.5, 35.6, and 21.8 mGy for DSA and 19.0, 16.9, 20.4, and 14.8 mGy for CTA, respectively. The conversion factors from DAP and DLP to effective dose were calculated. CONCLUSIONS: The effective dose for CTA assessment of cerebral vessels was approximately one-fifth the dose compared with DSA. In the imaging of cervicocerebral vessels, the effective dose for CTA was approximately one-third higher compared with DSA.

Patency and Complications of Percutaneously Inserted Metallic Stents in Malignant Biliary Obstruction

PURPOSE The aim of this study was to analyze the patency of percutaneously inserted metallic stents in malignant biliary obstruction and to evaluate all the complications associated with the stents and the reinterventions needed. MATERIALS AND METHODS Thirty-nine patients with 42 malignant strictures were treated percutaneously with 55 metallic self-expandable stents. Forty-eight were Wallstents and seven were Memotherm stents. Twenty-five strictures were hilar, 16 were in the common bile duct, and one was in the hepaticojejunal anastomosis. The patients were followed until death and the mean follow-up was 6.4 months. RESULTS Stent insertion was successful in 97% of the patients. Thirty percent had early complications (<30 days), and as many as 66% had late complications, including stent occlusions, which were seen in 10 patients. The patency rates of patients with cholangio-carcinoma were significantly lower than those of the patients with other diagnoses. There was also a tendency toward obstruction with less dilation of the stents, Y, T or tandem-style stent placement, an increasing number of stents, longer strictures, and hilar strictures. Thirty-one percent of the patients alive after the first 30 days had late reinterventions. CONCLUSIONS Although metallic stents offer an alternative in the palliation of malignant bile duct obstruction, there seem to be numerous early and late complications.

Central nervous system-related symptoms and findings are common in acute Puumala hantavirus infection.

Abstract Background. Puumala hantavirus (PUUV) causes a hemorrhagic fever with renal syndrome (HFRS) also called nephropathia epidemica (NE). Recent case reports and retrospective studies suggest that NE may damage the pituitary gland. Based on these observations, our goal was to explore the nature of this complication prospectively. Methods. A total of 58 hospitalized patients with acute NE volunteered to participate. Central nervous system (CNS) symptoms were recorded, cerebrospinal fluid (CSF) samples were collected, human leukocyte antigen (HLA) haplotype was analyzed, brain magnetic resonance imaging (MRI) was acquired, and electroencephalography (EEG) was recorded. Patients with abnormal pituitary MRI finding were examined by an endocrinologist. Results. Most patients experienced CNS symptoms, and half of the CSF samples were positive for PUUV IgM, elevated protein level, or leukocyte count. CSF of patients negative for DR15(2)-DQ6 haplotype was less frequently affected. MRI revealed pituitary hemorrhage in two patients; these two patients suffered sudden loss of vision associated with headache, and they both developed hypopituitarism. Only one patient required long-term hormonal replacement therapy. Conclusion. CNS-related symptoms and inflammation in the CSF are common in acute NE. Genetic properties of the host may predispose to CNS involvement. It does seem that pituitary injury and subsequent hormonal insufficiency may complicate the recovery.

Chronic hydrocephalus after neurosurgical and endovascular treatment of ruptured intracranial aneurysms

Background: Chronic hydrocephalus is a common sequela of subarachnoid hemorrhage (SAH). The technical procedure used to treat intracranial aneurysms, whether neurosurgical clipping or endovascular coiling, may lead to differences in the incidence of chronic posthemorrhagic hydrocephalus. Purpose: To compare the effects of early neurosurgical and early endovascular treatment on the development of chronic hydrocephalus in patients with SAH. Material and Methods: A retrospective study included 102 clipped and 107 coiled patients with aneurysmal SAH. Clinical condition at admission and shunt dependence were verified from patient data records. The initial and follow-up computed tomography (CT) images were reviewed, and the amount and distribution of blood and the occurrence of hydrocephalus were registered. The values of the cella media index and the width of the third ventricle were calculated. Statistical analysis of the data was performed. Results: No statistically significant differences in the incidence of chronic hydrocephalus or the need for shunting emerged between the treatment groups. After clipping 35% and after coiling 39% of the patients developed chronic hydrocephalus. Twenty-nine percent of the clipped and 31% of the coiled patients underwent a shunt operation. Conclusion: The treatment method used for acutely ruptured intracranial aneurysms, i.e., neurosurgical clipping or endovascular coiling, has no statistically significant effect on the development of chronic hydrocephalus.

Early rebleeding after coiling of ruptured intracranial aneurysms

Background: Early rebleeding after coiling of a ruptured intracranial aneurysm (IA) may cause disability or death. The incidence and predictors of early rebleeding have previously been sparsely investigated. Purpose: To assess the incidence and risk factors of early rebleeding after coiling of a ruptured IA and to analyze the outcome of the patients suffering early rehemorrhage. Material and Methods: The data of 194 consecutive acutely (within 3 days) coiled patients with saccular ruptured IAs were analyzed. Age, gender, hypertension, aneurysm multiplicity, Hunt et Hess (HH) grade, intracerebral hematoma (ICH), intraventricular hematoma (IVH), external ventricular drainage (EVD), aneurysm location and size, and the grade of the initial aneurysm occlusion were tested to find the risk factors for early rebleeding. The outcome of the patients suffering rehemorrhage was verified. Results: Early rebleeding after coiling occurred in 7 patients out of 194 (3.6%). The presence of an ICH at admission and HH grade 3–5 before coiling were significant risk factors for rebleeding. An early rehemorrhage appeared as an enlargement of the initial ICH in all of these patients. Six of seven patients had good outcome (Glasgow Outcome Scale, GOS, 3–5). Logistic regression analysis did not find any other statistically significant risk factors. Conclusion: The incidence of early rebleeding after acutely coiled ruptured IA was 3.6%. Risk factors for post-procedural rehemorrhage were the presence of ICH on the initial CT and HH grade 3–5 before coiling. Early rebleeding appeared exclusively as an enlargement of the initial ICH and not an increased amount of blood in the subarachnoid space.

Pulse repetition time and contrast enhancement: simulation study of Gd-BOPTA and conventional contrast agent at different field strengths.

Objectives:To investigate theoretically enhancement and optimal pulse repetition times for Gd-BOPTA and Gd-DTPA enhanced brain imaging at 0.23, 1.5, and 3.0 T. Methods:The theoretical relaxation times of unenhanced, conventional contrast agent (Gd-DTPA) and new generation contrast agent (Gd-BOPTA) enhanced glioma were calculated. Then, simulation of the signals and contrasts as a function of concentration and pulse repetition time (TR) in spin echo sequence was done at 0.23, 1.5, and 3.0 T. The effect of echo time (TE) on tumor-white matter contrast was also clarified. Three patient cases were imaged at 0.23 T as a test of principle. Results:Gd-BOPTA may give substantially better glioma-to-white matter contrast than Gd-DTPA but is more sensitive to the length of TR. These characteristics are accentuated at 0.23 T. Optimal TR lengths are shorter for Gd-BOPTA than for Gd-DTPA enhanced imaging at all field strengths. TR optimized for Gd-DTPA may thus give suboptimal contrast in Gd-BOPTA enhanced imaging. Higher enhancement with Gd-BOPTA is further accentuated by short TE. Conclusion:Appropriate TRs at 0.23 T appear to be approximately 300 to 400 milliseconds and 250 to 300 milliseconds, at 1.5 T 500 to 600 milliseconds and 400 to 450 milliseconds and at 3.0 T 550 to 650 milliseconds and 475 to 525 milliseconds using Gd-DTPA and Gd-BOPTA, respectively. For Gd-BOPTA enhanced imaging, it seems justified to optimize TR according to contrast and seek options like parallel excitation (Hadamard encoding) for increasing the number of slices and SNR.

Value of the quantity and distribution of subarachnoid haemorrhage on CT in the localization of a ruptured cerebral aneurysm

Summary¶Background. Computed tomography (CT) is the “gold standard” for detecting subarachnoid haemorrhage (SAH) and digital subtraction angiography (DSA) for visualising the vascular pathology. We studied retrospectively 180 patients with subarachnoid haemorrhage (SAH) who underwent first non-enhanced computed tomography (CT), then digital subtraction angiography (DSA) and finally operative aneurysm clipping. Our aim was to assess if the location of the ruptured aneurysm could be predicted on the basis of the quantity and distribution of haemorrhage on the initial CT scan.Methods. 180 patients with SAH were retrospectively studied. All the CT and DSA examinations were performed at the same hospital. CT was performed within 24 hours after the initial haemorrhage. DSA was performed after the CT, within 48 hours after the initial haemorrhage. Two neuroradiologists, blind to the DSA results, analysed and scored independently the quantity and distribution of the haemorrhage and predicted the site of the ruptured aneurysm on the basis of the non-enhanced CT. DSA provided the location of the ruptured aneurysm. All the patients were operated upon, and the location of the ruptured aneurysm was determined.Findings. The overall reliability value (κ-value) between the two neuroradiologists for locating all ruptured aneurysms was 0.780. The corresponding value for the right MCA was 0.911, that for the left MCA 0.877 and that for the AcoA 0.736. Not all of the κ-values were calculated, either because the location of the rupture was constant or because the number of ruptures in the vessel was too small. Subarachnoid haemorrhage with a parenchymal hematoma is an excellent predictor of the site of the ruptured aneurysm with a statistical significance of p=0.003.Interpretation. The quantity and pattern of the blood clot on CT within the day of onset of SAH is a reliable and quick tool for locating a ruptured MCA or AcoA aneurysm. It is not, however, reliable for locating other ruptured aneurysms. Subarachnoid haemorrhage with a parenchymal hematoma is an excellent predictor of the site of a ruptured aneurysm.

Young male patients are at elevated risk of developing serious central nervous system complications during acute Puumala hantavirus infection

BackgroundOur aim was to characterize clinical properties and laboratory parameters in patients with or without cerebrospinal fluid (CSF) findings suggestive of central nervous system (CNS) involvement, and especially those who developed serious CNS complications during acute nephropathia epidemica (NE) caused by Puumala hantavirus (PUUV) infection.MethodsA prospective cohort of 40 patients with acute NE and no signs of major CNS complications was analyzed. In addition, 8 patients with major CNS complications associated with NE were characterized. We collected data of CNS symptoms, CSF analysis, brain magnetic resonance imaging (MRI) results, electroencephalography (EEG) recordings, kidney function, and a number of laboratory parameters. Selected patients were evaluated by an ophthalmologist.ResultsPatients with a positive CSF PUUV IgM finding or major CNS complications were more often males (p < 0.05) and they had higher plasma creatinine values (p < 0.001) compared to those with negative CSF PUUV IgM. The degree of tissue edema did not explain the CSF findings. Patients with major CNS complications were younger than those with negative CSF PUUV IgM finding (52.9 vs. 38.5 years, p < 0.05). Some patients developed permanent neurological and ophthalmological impairments.ConclusionsCNS and ocular involvement during and after acute NE can cause permanent damage and these symptoms seem to be attributable to true infection of the CNS rather than increased tissue permeability. The possibility of this condition should be borne in mind especially in young male patients.

Mild traumatic brain injury diagnosis frequently remains unrecorded in subjects with craniofacial fractures.

BACKGROUND Traumatic brain injuries (TBI) in subjects with craniofacial fractures are usually diagnosed by emergency room physicians. We investigated how often TBI remains unrecorded in these subjects, and whether diagnostic accuracy has improved after the implementation of new TBI guidelines. METHODS All subjects with craniofacial fractures admitted to Oulu University Hospital in 1999 and in 2007 were retrospectively identified. New guidelines for improving the diagnostic accuracy of TBI were implemented between 2000 and 2006. Clinical symptoms of TBI were gathered from notes on hospital charts and compared to the recorded diagnoses at discharge. Logistic regression was used to identify independent predictors for TBI to remain unrecorded. RESULTS Of 194 subjects with craniofacial fracture, 111(57%) had TBI, 40 in 1999 and 71 in 2007. Fifty-one TBIs (46%) remained unrecorded at discharge, 48 being mild and 3 moderate-to-severe. Subjects with unrecorded TBI were significantly less frequently referred to follow-up visits. Failures to record the TBI diagnosis were less frequent (29/71, 41%) in 2007 than in 1999 (22/40, 55%), but the difference was not statistically significant. The most significant independent predictor for this failure was the clinical specialty (other than neurology/neurosurgery) of the examining physician (p<0.001). The subjects alcohol intoxication did not hamper the diagnosis of TBI. CONCLUSIONS TBIs remain frequently unrecorded in subjects with craniofacial fractures. Recording of mild TBI slightly but insignificantly improved after the implementation of new guidelines.

A portable diagnostic workstation based on a Webpad: implementation and evaluation

A wireless hand-held Webpad device was used to review a sample set of cranial computerized tomography (CT) studies to assess its diagnostic capabilities and its feasibility as a portable diagnostic workstation for radiology. The data-set consisted of 30 head CT studies of emergency cases. Two neuroradiologists and a senior radiologist participated in the evaluation of the portable workstation. They used a Web-based viewer that we developed, which provided all the major functionalities required for radiological image review. The reported radiological findings and diagnoses were compared with a gold standard, comprising a set of diagnoses previously formulated by a consensus panel of radiologists who had reviewed the original studies. The diagnoses made using the Webpad were correct (no major discrepancies) in 82 out of 90 interpretations (91%), which is comparable to the accuracy reported in image review with a conventional radiological workstation. The average total working time per diagnosis was 5 min 25 s (range 2–12 min). The simplicity of use of the system and its low cost make it suitable for distributing radiological studies within hospital facilities.