Biomedical subjects

S Savolainen

Publications and source records attributed to S Savolainen.

At least 19 recordsLinked to original sources

PubMed2000

Transmission imaging for registration of ictal and interictal single-photon emission tomography, magnetic resonance imaging and electroencephalography.

A method developed for registration of ictal and interictal single-photon emission tomography (SPET), magnetic resonance imaging (MRI) and electroencephalography (EEG) is described. For SPET studies, technetium-99m ethyl cysteinate dimer (ECD) was injected intravenously while the patient was monitored on video-EEG to document the ictal or interictal state. Imaging was performed using a triple-head gamma camera equipped with a transmission imaging device using a gadolinium-153 source. The images (128x128 pixels, voxel size 3.7x3.7x3.6 mm3) were reconstructed using an iterative algorithm and postfiltered with a Wiener filter. The gold-plated silver electrodes on the patient's scalp were utilized as markers for registration of the ictal and interictal SPET images, as these metallic markers were clearly seen on the transmission images. Fitting of the marker sets was based on a non-iterative least squares method. The interictal SPET image was subtracted from the ictal image after scaling. The T1-weighted MPRAGE MR images with voxel size of 1.0x1.0x1.0 mm3 were obtained with a 1.5-T scanner. For registration of MR and subtraction SPET images, the external marker set of the ictal SPET study was fitted to the surface of the head segmented from MR images. The SPET registration was tested with a phantom experiment. Registration of ictal and interictal SPET in five patient studies resulted in a 2-mm RMS residual of the marker sets. The estimated RMS error of registration in the final result combining locations of the electrodes, subtraction SPET and MR images was 3-5 mm. In conclusion, transmission imaging can be utilized for an accurate and easily implemented registration procedure for ictal and interictal SPET, MRI and EEG.

Adolescent↗

PubMed2000

MR imaging of the hippocampus in normal pressure hydrocephalus: correlations with cortical Alzheimer's disease confirmed by pathologic analysis.

BACKGROUND AND PURPOSE: MR studies have shown hippocampal atrophy to be a sensitive diagnostic feature of Alzheimer's disease (AD). In this study, we measured the hippocampal volumes of patients with a clinical diagnosis of normal pressure hydrocephalus (NPH), a potentially reversible cause of dementia when shunted. Further, we examined the relationship between the hippocampal volumes and cortical AD pathologic findings, intracranial pressure, and clinical outcomes in cases of NPH. METHODS: We measured hippocampal volumes from 37 patients with a clinical diagnosis of NPH (27 control volunteers and 24 patients with AD). The patients with NPH underwent biopsy, and their clinical outcomes were followed for a year. RESULTS: Compared with those for control volunteers, the findings for patients with NPH included a minor left-side decrease in the hippocampal volumes (P < .05). Compared with those for patients with AD, the findings for patients with NPH included significantly larger hippocampi on both sides. Although not statistically significant, trends toward larger volumes were observed in patients with NPH who had elevated intracranial pressure, who benefited from shunting, and who did not display cortical AD pathologic findings. CONCLUSIONS: Measurements of hippocampal volumes among patients with a clinical diagnosis of NPH have clear clinical implications, providing diagnostic discrimination from AD and possibly prediction of clinical outcome after shunting.

Aged↗

PubMed1999

Prevalence of Alzheimer's disease in patients investigated for presumed normal pressure hydrocephalus: a clinical and neuropathological study.

During 1991-1995, 223 patients were investigated in the Department of Neurosurgery, Kuopio University Hospital because of a clinical and CT diagnosis of NPH. All patients underwent intracranial pressure measurements and were formed into 3 biopsy groups. Group A included incidentally biopsied patients (104 patients, 34 biopsies) seen during 1991-1992; Group B was a prospective study group from 1993-1995 (all 51 patients biopsied); and Group C patients excluded from Group B (68 patients, 34 biopsies) by age and concomitant diseases. A cortical biopsy was taken before intracranial pressure recording altogether in 118 of the 223 patients. The biopsy revealed normal brain tissue in 66 patients. Prevalence of Alzheimer's disease (AD) in biopsied patients was 42% in Group A, 31.3% in Group B and 50% in Group C. A shunt was placed according to pressure measurement in 110 patients; of these, 8 had both AD and raised ICP. Two patients with both AD and raised ICP improved after shunt placement during the first follow-up year, 4 patients deteriorated and the condition of 2 was similar to that before shunting. The frequency of haematomas after biopsy was 2.9% in groups A and C; in Group B patients had no postoperative haematomas. There was no difference in the incidence of complications in patients who had or did not have a biopsy. The relatively high prevalence of AD in patients with NPH may explain the unsuccessful recovery of many patients after shunt placement. Cortical biopsy is an effective and safe method for finding the co-existence of AD and thus improving the diagnosis of NPH and may prevent unnecessary shunt surgery.

Aged↗

PubMed1999

111In-labelled bleomycin complex for the differentiation of high- and low-grade gliomas.

The aim of this study was to evaluate 111In-labelled bleomycin complex (111In-BLMC) SPET in the differentiation of high- and low-grade gliomas. Nineteen glioma patients, 14 with high-grade and five with low-grade tumours, were studied 1, 4 and 24 h after the injection of 111In-BLMC. In the high-grade glioma group, there was significant uptake of 111In-BLMC in 12 patients and no uptake in two patients based on the visual classification of SPET images at 4 and 24 h. In the low-grade glioma group, one patient had low uptake at 4 and 24 h, but the other four patients showed no visible uptake. The mean tumour to extracerebral circulation activity ratio (T/Cr) at 4 h was 0.13 +/- 0.10 (n = 5) in low-grade gliomas and 1.7 +/- 1.0 (n = 14) in high-grade gliomas. At 24 h the T/Cr ratios were 0.56 +/- 0.21 and 3.4 +/- 1.7, respectively. The mean tumour to contralateral normal brain activity ratios (T/Br) were 5.0 +/- 3.9 (4 h) and 3.0 +/- 2.8 (24 h) in low-grade gliomas, and 37.2 +/- 37.3 (4 h) and 8.3 +/- 8.2 (24 h) in high-grade gliomas. These higher T/Br ratios did not, however, result in improved differentiation between the two groups of gliomas; at 4 h the T/Cr and T/Br ratios were of equal value, as two high-grade gliomas would have been misclassified as low-grade, but at 24 h the T/Br ratio resulted in more misclassifications. Our results show that 111In-BLMC can be used in the differentiation of high- and low-grade gliomas and that the selection of the reference area for calculating tumour to non-tumour ratios is important.

Adult↗

PubMed1999

Low-altitude overflights of fighters and the risk of hearing loss.

BACKGROUND AND OBJECTIVE: Much data are available on noise properties which cause hearing loss. There are not, however, reports on the effects of low-altitude overflight noise on the permanent threshold shift (PTS). METHODS: Low-altitude overflight noise generated by the Finnish Air Force's jet fighters and an advanced jet trainer was measured with flight distances varying from 50-310 m from the measurement point. The aircraft were always subsonic, velocities being usually 0.9 Mach or less. The measurements were undertaken because of two claims for the compensation of hearing loss caused by overflights of jet fighters on cross-country training missions. RESULTS: Peak noise levels (LCpeak) varied from 109-150 dB depending on aircraft type and the use of afterburner. The 1-s single A-weighted exposure levels (ASEL) during these overflights were 95-135 dB which correspond to daily (8 h) exposure levels of 50-90 dB. CONCLUSIONS: According to these results and the principles of noise evaluation, there should be no risk of permanent hearing loss when the distance to an overflying jet fighter is more than 200 m. However, we have received two claims, and the audiometric analyses of two subjects who had suffered hearing loss in one ear in Finland during the 1990s may indicate that there is very likely a connection between the incidents and the hearing losses.

Acceleration↗

PubMed1999

Influence of strict regulations on the use of hearing protectors in the Finnish Defence Forces.

The regulations concerning hearing protection during military training in the Finnish Defence Forces were renewed in 1989. The material of this prospective study concerns 912 consecutive conscripts (463 before and 449 after the new regulations) who were referred to the Central Military Hospital for acute acoustic trauma (AAT). We focused on three issues: (1) general habits regarding the use of hearing protection during shooting drills and combat training; (2) hearing protection at the moment of AAT; and (3) the cause of AAT. In combat training, the use of any hearing protectors was only 50% before the new regulations, but after they came into force the proportion was greater than 90%, and more effective protectors were used. However, at the time of AAT the hearing protection was absent in more than 80% of cases in both groups. The most common cause of AAT was small arms in both groups (83%).

Adult↗

PubMed1998

Comparative immunohistochemical study of group II (synovial-type) and group IV (cytosolic) phospholipases A2 in disc prolapse tissue.

Phospholipase A2 (PLA2) has been suggested to be present in herniated disc tissue and it could possibly be involved in sciatica/ discogenic back pain mechanisms. In the present study the occurrence of two different phospholipase A2 enzymes, (1) low molecular weight (14 kDa) group II synovial-type (sPLA2) and (2) high molecular weight (85 kDa) group IV cytosolic (cPLA2), were compared. Fifty-three disc prolapses obtained at disc operations were analyzed by immunohistochemistry, using anti-human monoclonal antibodies to sPLA2 and cPLA2, respectively. Only cell-associated (disc cells, hyaline cartilage chondrocytes) sPLA2 and cPLA2 immunoreactivity could be observed. The results showed that sPLA2 was more common (25/53, 47%) than cPLA2 (13/53, 25%). sPLA2 and cPLA2 were simultaneously present in 13 of 53 samples (25%). However, both PLA2 enzymes were predominantly present in hyaline cartilage cells (sPLA2: 16/53, cPLA2: 5/53), being less commonly observed in disc cells (sPLA2: 6/53, cPLA2: 3/53). In addition, three samples for sPLA2 and two samples for cPLA2 exhibited immunoreactivity in cartilage and disc cells simultaneously. sPLA2 was observed in no other locations, but in 3 of 53 samples cPLA2 was observed more diffusely in areas of granulation tissue, possibly in macrophages. No gender- or age-related dependence for either type of PLA2 enzyme immunoreactivity could be observed. Neither did their occurrence relate to clinical data such as straight leg raising or neurological deficit. The results do not support a major role for either of the two disc-cell-associated PLA2s in disc pathophysiology. For both enzymes, the major pool appears to reside in cartilage tissue cells, presumably in dislodged end-plate fragments. Disc cells are apparently unlikely candidates for major PLA2 storage.

Adult↗

PubMed1998

Multiphase segmented k-space velocity mapping in pulsatile flow waveforms.

The aim of the present study was to obtain the precision of flow measurement in breath-hold segmented k-space flow sequences. The results are based on studies of pulsatile flow in a phantom tube. The ultimate purpose is to use these sequences to measure coronary flow. In abdominal and cardiothoracic magnetic resonance imaging the image quality is degraded due to respiratory motion. In the segmented k-space acquisition method, one obtains many phase-encoding steps or views per cardiac phase. This shortens imaging time in the order of phase-encoding lines and makes it possible to image in a single breath-hold, thereby eliminating respiratory artefacts and improving edge detection. With breath-hold multiframe cine flow images it is possible to evaluate flow in all abdominal and cardiothoracic areas, including the coronary arteries. Our study shows that velocity curves shift in time when the number of k-space ky-lines per segment (LPS) are varied; this shift is linear as a function of LPS. The mean velocity Vmean in the center of mass of the pulsatile peak is constant (Vmean = 40.1 +/- 2.9 cm/s) and time t = -10.1 x LPS + 268 (r = 0.993, p < 0.0001). Correlation between theoretical and experimental flow curves is also linear as a function of LPS: C = -0.977 * LPS (r = 0.987, p < 0.0001). It is concluded that velocity curves move with LPS and are smoothed when the breath-hold velocity mapping is used. The more LPS is gathered the more inaccurate results are. LPS 7 or more cannot be considered clinically relevant.

Artifacts↗

PubMed1998

A prospective randomized study of anterior single-level cervical disc operations with long-term follow-up: surgical fusion is unnecessary.

OBJECTIVE: After 40 years of experience with anterior cervical operations, whether to fuse is still controversial. This study seeks to answer this question. METHODS: In this prospective randomized study, we operated on 91 patients with single-level cervical root compression using three different methods: 1) discectomy without fusion, 2) fusion with autologous bone graft, and 3) fusion with autologous bone graft plus plating. RESULTS: After 4 years of follow-up, the radiological results indicated that complete bony union was achieved in almost all cases. A slight kyphosis developed in 62.5% of the patients who had undergone discectomy, 40% of the patients who had undergone fusion, and 44% of the patients who had undergone fusion plus plating (not significant). The clinical outcomes were good for 76% of the patients who had undergone discectomy, 82% who had undergone fusion, and 73% who had undergone fusion plus plating. The outcomes were poor in 0, 4, and 4%, respectively (not significant). CONCLUSION: According to this study, satisfactory results can be achieved by performing simple discectomy to treat single-level cervical root compressive disease.

Adult↗

PubMed1998

Future developments in nuclear medicine instrumentation: a review.

This review article forecasts developments in nuclear medicine instrumentation which are on the horizon. Special attention is paid to the physical properties of detectors and multiple-processor parallel processing systems needed for fast and high-quality imaging in emission tomography. Advances in detector technology will improve imaging resolution below 5 mm and will increase sensitivity and quantitative accuracy. In addition, high count rate list-mode acquisition enables 'true' four-dimensional data-sets. A sandwich-like construction of two different crystals allows the simultaneous use of conventional tracers and positron tracers (multiple emission tomography, MET). Transmission-based attenuation and scatter compensation with fast iterative reconstruction methods will further improve image quality. The clinical and scientific importance of improved images and the limits on advances in instrumentation are also reviewed.

Equipment Design↗

PubMed1998

Noise attenuation of communication hearing protectors against impulses from assault rifle.

The noise attenuation values of commercial and military versions of earmuffs were measured using a Finnish assault rifle (RK762) as the sound source. The C-weighted peak level at the entrance of the left ear of the shooter was 156 dB (SD 1.0 dB; n = 25 shots). The noise was analyzed both outside and inside ear muffs on military volunteers on an open shooting range. All the earmuffs attenuated the C-weighted peak level to a value of less than 135 dB, which is less than the proposed values recommended by hearing damage criteria. Communication hearing protectors seem to function and attenuate sufficiently against the peak levels of the impulse noises used in this study.

Ear Protective Devices↗

PubMed1997

Accuracy of a registration procedure for brain SPET and MRI: phantom and simulation studies.

Phantom experiments and simulations were performed to evaluate the significance of different error sources in a clinical registration procedure for brain SPET and MRI based on external markers. The results from the phantom experiments were used to adjust the error model for simulations. In the phantom experiments, 13-14 external markers were attached to the surface of a three-dimensional brain phantom for computing registration. Three internal test markers were used to estimate the accuracy of registration. The phantom was imaged with two different SPET and MRI devices. The mean root-mean-squared (RMS) residual of the locations of the test markers after registration using different combinations of four external markers varied from 3.5 +/- 1.0 to 5.2 +/- 1.3 mm depending on the imaging equipment and parameters used. The accuracy improved with an increasing number of external markers, from 3.2 +/- 0.5 to 4.9 +/- 0.5 mm for 6 markers and from 3.1 +/- 0.1 to 4.7 +/- 0.1 mm for 13 markers. In simulations, the external markers had an error comparable to the corresponding error in the phantom experiments. The error in the test markers was varied independently of that of the external markers. When the locating error of the test markers was removed, about 2 mm of the residuals of the test markers were found to come from this source. When an error comparable to the resolution of the original images (7-10 mm for SPET, 2 mm for MRI) was included in the test markers, the largest mean RMS residual after registration was smaller than the resolution error (8.8 +/- 1.1 mm). This was due to the accuracy of localization of the external markers and the fact that the direction of the error was random for each marker. The size of the registration error of an image volume was site-dependent, being minimal near the centre of mass of the external markers. When comparing the error with the spatial resolution of SPET, it was concluded that the accuracy of registration is not the limiting factor in region-of-interest analysis of registered images, provided that the design and attachment of the marker system are appropriate.

Brain↗

PubMed1997

Comparative effectiveness and safety of cefdinir and amoxicillin-clavulanate in treatment of acute community-acquired bacterial sinusitis. Cefdinir Sinusitis Study Group.

Cefdinir is an extended-spectrum oral cephalosporin that is active against pathogens commonly seen in acute community-acquired bacterial sinusitis (ACABS), including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Two randomized, investigator-blind, multicenter trials (one in the United States and one in Europe) compared two dosage regimens of cefdinir (600 mg once a day for 10 days and 300 mg twice a day for 10 days) to amoxicillin-clavulanate (A-C) (500 mg three times a day for 10 days) for adult and adolescent patients with ACABS. Twelve hundred twenty-nine patients entered the U.S. study, 698 with antral puncture; 569 patients entered the European study, all with antral puncture. Clinical response (cure or improvement) was determined 7 to 14 days and 3 to 5 weeks posttherapy. Microbiologic eradication rates were determined 10 to 30 days posttherapy in a subset of patients who underwent pre- and posttherapy sinus aspirate culture. Rates of adverse events and treatment discontinuations due to adverse events were examined. Cefdinir, given once or twice daily, was as effective clinically (approximately 90% cure rate) as amoxicillin-clavulanate given three times daily in the treatment of ACABS. Microbiologic eradication rates were also similar in the three groups. The major side effect was mild diarrhea, occurring in approximately 20% of each group. Cefdinir caused fewer adverse events requiring treatment discontinuation.

Adolescent↗

PubMed1997

Do simple laboratory tests help in etiologic diagnosis in acute maxillary sinusitis?

The aim of the present study was to evaluate whether the results of such simple hematologic tests as erythrocyte sedimentation rate (ESR), white blood cell count (WBC) and C-reactive protein (CRP) could give any useful information about the causative agents in 176 patients with acute maxillary sinusitis (AMS). The great majority of tests (82%) showed values which were within normal limits. This may be due to the fact that 22% of AMS cases were culture negative for bacteria and about 60% of culture positive cases had Haemophilus influenzae as the etiologic agent. Significantly raised test values were seen in connection with Streptococcus pyogenes in the majority of cases, less frequently with Streptococcus pneumoniae and rarely with Haemophilus influenzae. We conclude that none of the evaluated routine blood tests are particularly sensitive indicators of the specific etiology of AMS in general. However, elevated CRP values (> 40 mg/l) associated with AMS should alert the physician to the suspicion of Streptococcus pyogenes or Streptococcus pneumoniae in etiology, since both, if left untreated, may lead to sinus empyema. With CRP or other evaluated tests Haemophilus influenzae- or Branhamella catarrhalis-positive AMS cannot be distinguished from a purely viral disease.

Acute Disease↗

PubMed1997

An ultrasound device in the diagnosis of acute maxillary sinusitis.

This multicenter study comprised 161 consecutive and unselected patients with suspected acute maxillary sinusitis (AMS). Altogether 322 maxillary sinuses were examined radiologically and by untrasound device (US). Of these, 234 antra were punctured, aspirated and irrigated. The volume of secretion coming out by irrigation was evaluated. The results of US, x-ray and irrigation were compared. For US, the proportion of correct positive results was 82.7% when the secretion volume was heavy, 78.6% when the secretion volume was moderate and 84.3% when the secretion volume was slight. When US finding was compared with the puncture result, the US gave false positive results in 8% of the cases and false negative results in 18.5% of the cases. Out of 187 positive irrigation findings, radiographs revealed fluid retention in 99 cases (score 3-6) (53%). Similarly, 11 radiographs showed fluid retention in 47 cases of negative irrigation findings (23.4%). Statistical calculation shows that both US and radiology were equally reliable in diagnosing fluid retention and sinusitis, when the results are compared with the findings of the sinus puncture. US and radiology gave false positive findings almost equally (p > 0.05). On the other hand, when the volume of secretion was slight (< 1 ml), US gave a fluid echo finding more often than radiology showed fluid retention.

Acute Disease↗

PubMed1997

Radiological findings in the maxillary sinuses of symptomless young men.

The maxillary sinuses were examined radiologically by occipitomental projection (Waters' view) in 404 conscripts without any symptoms of sinusitis. Abnormalities were found in 188 (23.3%) of all 808 sinuses, the most common being mucosal thickening of > 6 mm (12.3% of the sinuses), cysts or polyps (7.2%), and completely opacified sinus (3.3%). Normal x-ray findings were more common in the conscripts examined during the summer months and mucosal thickening was more frequently encountered in winter than in summer. Nasal bacteria were studied in 100 cases. Findings of normal bacterial flora and of pathogenic bacteria were equally frequent among subjects with normal sinus x-ray (score 0 and 1) and subjects with severe abnormalities (scores 3-6), but mucosal cysts (score 2) was more often combined with pathogens in the nose. Mucosal thickening was more often observed in non-allergic than in allergic persons; thus allergy did not seem to increase radiological abnormalities. Of young men engaged in outdoor activities, about one fifth seem to have significant chronic mucous membrane abnormalities in the maxillary antra without clinical symptoms. In 1-2% of cases secretion is detected in the maxillary sinus indicating a subclinical sinusitis.

Adult↗

PubMed1997

Impulse noise and acute acoustic trauma in Finnish conscripts. Number of shots fired and safe distances.

This prospective study of acute acoustic trauma (AAT) from exposure to impulse noise during compulsory military service focused on three issues the number of shot or explosion impulses that the conscript was exposed to at the time of AAT, distance of injured ear from causal firearm, and the circumstances under which AAT occurred protected ears. The series includes 449 consecutive, verified cases of AAT seen at the Central Military Hospital in Helsinki, Finland, in the period 1989-1993. AAT usually occurred during combat training (87%) as a result of exposure to impulses from small arms (83%). In 41%. AAT was caused by a single shot or detonation impulse. As many as 92% of all AATs occurred within 2 m of the causal firearm. Fourteen percent were wearing hearing protectors when the accident took place, but every third had badly fitting protectors or had neglected safety regulations and used insufficient protection. Of all AATs caused by one noise impulse in protected ears. 83% were attributable to heavy arms and only 14% to small arms. The results of the study suggest that combined use of earmuffs and earplugs in association with a safe distance of over 5 m from the noise source gives adequate protection against AAT. However, for conscripts using certain heavy arms e.g. hazooka. more effective hearing protection should be developed.

Acute Disease↗

PubMed1997

Bacterial findings in acute maxillary sinusitis--European study.

Bacteriology of acute maxillary sinusitis was studied in 569 patients in 16 centers of 6 countries located throughout Europe during 1992-1994 by ENT specialists. Patients with symptoms of acute sinusitis lasting less than 3 weeks with ongoing purulent nasal discharge were included. Diagnosis was verified by sinus x-ray or ultrasonography and a positive aspiration finding in maxillary sinus puncture. One or more pathogens were isolated from the maxillary sinus aspirates of 375 (66%) patients. Fifty-six percent of patients harboured 1 pathogen and 10% multiple pathogenic organisms, respectively. Haemophilus influenzae was the most common pathogen isolated (148 isolates), occurring as a single pathogen in 14% of the patients. The occurrence of H. influenzae was highest in Finnish military hospital patients (43-48%), as compared with the non-military Finnish patients (9-11%) or to patients from other European centers (mean 13%). H. influenzae was more frequently beta-lactamase positive in other European centers (22%) than in Finnish centers (7%). Streptococcus pneumoniae was the most common pathogen isolated in other European centers (20%) but second most common in Finnish centers (13%). Moraxella catarrhalis occurred at quite similar frequency among Finnish centers (9-14%), but clearly less often in other centers (mean 4%). S. aureus, which in acute maxillary sinusitis is regarded as a contaminant from the nasal cavity, was more prevalent in other European centers (12%) than in Finnish centers (4%). In patients with acute maxillary sinusitis reliable bacteriological samples should be taken by antral aspiration directly from the diseased sinus.

Acute Disease↗