Biomedical subjects

S Hasebe

Publications and source records attributed to S Hasebe.

At least 37 records · Page 2Linked to original sources

PubMed1998

[Effect of the skull on brain perfusion SPECT imaging].

Because attenuation gradually decreases reconstructed counts from the periphery to the center portion of the object, the deep region far from the detector is not clearly observed if attenuation is not compensated. In brain perfusion SPECT, diagnosis is sometimes made using filtered back projection images without attenuation compensation (FBP). Brain perfusion SPECT has the unique characteristic that the radiopharmaceutical accumulates only within the brain and is never taken up by the surrounding skull. This study investigated the effect of skull on brain perfusion SPECT reconstructed with FBP. We theoretically derived the relation between the counts of brain and the linear attenuation coefficient of skull. It was found that the difference in reconstructed counts between the deep gray matter and peripheral gray matter decreased due to the existence of the skull. This result indicated that the deep gray matter was inclined to be visible if the FBP images were displayed according to relative counts normalized to the maximum count of each image. In order to confirm this, we made a numerical phantom with realistic human brain and skull contours on the basis of MR images from a normal volunteer. The linear attenuation coefficient of brain was assumed to be 0.15 cm-1, while that of skull was assumed to be 0.26 cm-1 (denoted as BONE+) or 0 cm-1 (BONE-). In accordance with the theoretical results, the deep gray matter of BONE+ images was more clearly observed than that of BONE- images, if these were displayed using the relative counts of each images. The physical phantom experiments also supported the theoretical and numerical phantom studies.

Cerebrovascular Circulation↗

PubMed1998

[Arterial infusion chemotherapy with SMANCS-Lipiodol for multiple hepatocellular carcinoma].

Fifty-five patients with hepatocellular carcinoma were treated with oily anticancer agent SMANCS dissolved in Lipiodol (SMANCS-LPD). The local response rate after the first arterial infusion in all patients was 39%, against 63% in 27 patients with Lipiodol accumulation occupying more than two thirds of tumor areas. The infusion therapy with SMANCS-LPD is adapted for a vascular-rich hepatocellular carcinoma. An infusion of 4 mg of SMANCS was ineffective for patients with tumors distributing in bilateral lobes of liver. Thus, an increase of infusion dosage or repeated infusions were recommended for such cases.

Aged↗

PubMed1998

Cause of posterior canal wall retraction after surgery from the viewpoint of mastoid conditions.

OBJECTIVE: To determine the relationship between preservation of the mastoid mucosa during ear surgery and retraction of the attic or posterior wall of the external auditory canal (EAC) and mastoid aeration after surgery. METHODS AND DESIGN: Retraction of the posterior EAC wall and mastoid aeration were evaluated after surgery in 48 individuals (50 ears) with cholesteatoma, adhesive otitis media, or chronic suppurative otitis media, in whom the posterior bony EAC walls were removed with or without preservation of mucosa and reconstructed with soft tissues alone (EAC skin and temporal fascia) during surgery. RESULTS: Postoperative computed tomography showed that in ears with notable retraction of the posterior EAC wall appearing like an open mastoid cavity, there was no air in the mastoid, whereas in ears with no or only slight retraction there was computed tomographic evidence of mastoid aeration. Second, notable retraction of the posterior EAC wall occurred in a significantly smaller percentage of ears in which at least the epitympanic mucosa had been able to be preserved during surgery than in those that had undergone removal of all mucosa (mastoidectomy). CONCLUSIONS: These results indicate that 1) preservation of epitympanic mucosa during surgery is an important factor for prevention of retraction of the posterior EAC wall and for reaeration of the mastoid after surgery, and 2) the intact canal wall technique seems to be indicated whenever at least the epitympanic mucosa can be preserved, and when no mucosa can be preserved the canal wall down procedure seems to be indicated.

Adult↗

PubMed1998

Biometric confirmation of the Hirschberg ratio in strabismic children.

PURPOSE: In the Hirschberg eye position test, the ratio of strabismic angle to decentration of the corneal reflex is dependent on two biometric parameters of the eye: the radius of the corneal curvature and the depth of the anterior chamber. This study was designed to confirm whether the Hirschberg conversion ratio (HR) previously determined for adults can be used for children of various ages despite structural growth of the eye. METHODS: For 262 eyes of 131 children with strabismus (age range, 6 months to 11 years), the radius of the corneal curvature was measured with an auto-keratometer and the anterior chamber depth with an A-scan ultrasound unit under general anesthesia before the surgery. Using these measurements, the HR was computed on the basis of a geometric model. RESULTS: The calculated HR was constant across the age range, and the mean+/-SD was 19.9+/-1.9 prism diopters/mm (95% confidence interval, 16.1-23.6 prism diopters/mm). The ratios for the two eyes in each subject showed good correlation (R = 0.854, P = 0.0001). Neither of the biometric measurements was significantly correlated with age, although considerable scatter of the measurements was observed. CONCLUSIONS: These results indicate that the averaged HR can be applied in children regardless of the patient's age, although intersubject variance of the ratio should be taken into account.

Anterior Chamber↗

PubMed1998

[Combined scatter and attenuation correction for 201Tl myocardial perfusion SPECT using OS-EM algorithm].

There are two possible ways to obtain scatter-corrected images with the ML-EM (maximum likelihood expectation maximization) algorithm: one is the subtraction of scatter estimate si from projection data pi, and then (pi-si) is used for scatter-corrected projection data (denoted as SC(T)); the other method is the addition of scatter estimate si to the projections calculated from the reconstructed image without performing data subtraction (SC(E)). This paper investigated these two ML-EM algorithms of combined scatter and attenuation correction on 201Tl myocardial perfusion SPECT imaging. Scatter windows were placed one full width at half maximum (FWHM) below and above the photopeak centerline. The scatter fraction in the primary peak was estimated using trapezoidal approximation by the triple energy window method. Phantom and clinical images were reconstructed using 6 iterations of ordered subsets EM algorithm (OS-EM). A cylindrical phantom with a cold-rod insert and a heart/thorax phantom with liver insert were used to evaluate scatter and the attenuation compensation technique. A cylindrical phantom filled with uniform 201Tl solution was used to evaluate statistical noise. The percent root-mean-square uncertainty (%RMSU) was used as a quantitative measure of noise amplification. %RMSU showed that the SC(E) method amplified noise less in comparison with the SC(T) method, however, no significant difference in image quality was observed between the two methods. In conclusion, both the SC(T) and SC(E) methods provided significant and similar improvement in the removal of scatter in 201Tl myocardial perfusion SPECT imaging.

Absorption↗

PubMed1997

Microvascular change of the anterior eye segment after tenotomy in the rabbit.

BACKGROUND: The microvascular changes secondary to anterior segment ischemia following tenotomy of the extraocular muscles have not been studied in the rabbit. METHODS: Using scanning electron microscopy of methyl-methacrylate ocular microvascular luminal castings, the anterior eye segment vasculature after tenotomy was documented and compared to that after occlusion of the bilateral long posterior ciliary arteries and that in the eyes that were not subjected to any surgical intervention. RESULTS: Five days and 1 week after the surgical intervention with tenotomy, microvascular change secondary to the anterior segment ischemia was not apparent, but 2 weeks after the tenotomy subtle evidence of ischemia such as new vessels in the iris was observed. Seven weeks after tenotomy, marked microvascular change was observed where corneal new vessels arose from the superior perilimbal arteries. In contrast, we found prominent microvascular changes 2 weeks after the occlusion of the long posterior ciliary arteries. CONCLUSIONS: Tenotomy of the rabbit eye causes microvascular change similar to that in occlusion of the long posterior ciliary arteries. This result suggests that the anterior ciliary artery of the rabbit contributes blood flow to the anterior eye segment and also has a stronger connection with the long posterior ciliary artery than previously reported.

Animals↗

PubMed1997

Compartmental analysis of asialoglycoprotein receptor scintigraphy for quantitative measurement of liver function: a multicentre study.

A multicentre study on multicompartmental analysis of hepatic scintigraphy using technetium-99m labelled galactosyl serum albumin (GSA), which binds to the asialoglycoprotein receptor, was carried out at seven institutions in Japan. Seventy-four patients with liver disease received 3 mg (185 MBq) of 99mTc-GSA by intravenous injection. Sequential scanning was performed 30 min after injection to obtain anterior images of the heart and liver, followed by single-photon emission tomography (SPET). The indices included in this analysis were hepatic blood flow (Q) and maximal receptor binding rate (Rmax), which showed a good correlation with semiquantitative ratio indices for 99mTc-GSA, namely the retention rate in blood (HH15) and the hepatic uptake rate (LHL15). Q and Rmax also showed a significant correlation with other measures of hepatic function. When patients were grouped according to the severity of chronic liver damage (hepatocellular functional damage), Q was reduced in the moderate and severe groups, while Rmax was reduced in proportion to the functional stage. Both parameters showed no inter-institution difference using analysis of co-variance with the functional stage as a co-variant. With regard to the hepatic uptake rate, anterior planar images and SPET images gave similar results for Q and Rmax. Acquisition times of 15 or 30 min provided the same results. The multicompartmental model analysis permitted comparable results to be obtained at institutions using different gamma cameras, and is therefore considered a universally applicable method. These results indicate that Q and Rmax are useful general indices for evaluating the functional reserve capacity of the liver.

Asialoglycoprotein Receptor↗

PubMed1997

Gas exchange function of the middle ear in patients with otitis media with effusion.

Gas exchange function through the middle ear mucosa was assessed using nitrous oxide (N2O) in patients with otitis media with effusion (OME), as well as in normal ears during elective surgery for unrelated disorders. In all normal ears except one (n = 43), an increase in pressure was observed after N2O inhalation. In 42 of 84 ears with OME, a pressure increase was observed, but not in the remaining 42 ears (50%), indicating that the gas exchange function in these latter ears was impaired. In 21 of the 42 ears showing no middle ear pressure increase following N2O inhalation, the middle ear pressure was again monitored after myringotomy and aspiration of the effusion A pressure increase was found in 16 ears, indicating that the impairment in gas exchange function in ears with OME may be reversible in most cases. Computed tomography of the mastoid was examined preoperatively in 66 ears, with the presence or absence of a middle ear pressure change well correlated in 57 ears with the presence or absence of mastoid aeration.

Adolescent↗

PubMed1997

Precision of the gallbladder ejection fraction obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy as compared with the contraction ratio in three-dimensional computed tomography.

UNLABELLED: The gallbladder ejection fraction (GBEF) obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy has been used as a parameter of gallbladder function. To determine the accuracy of GBEF, the relationship with the contraction ratio of the gallbladder (GBCR) obtained with three-dimensional helical computed tomography (3D-CT) was studied. PATIENTS AND METHODS: A normal volunteer, 8 patients suffering from cholecystolithiasis and a patient with gallbladder dyskinesia were examined. The percent initial dose (%ID) for the gallbladder and GBEF with hepatobiliary scintigraphy were used to compare the volume of the gallbladder and GBCR which was measured by 3D-CT. RESULTS: The %ID of the gallbladder was correlated with the volume of the gallbladder by 3D-CT (Y = 1.000X - 1.818, r = 0.928). GBEF was correlated well with GBCR by 3D-CT (Y = 0.916X + 6.296, r = 0.975). CONCLUSIONS: The %ID of the gallbladder obtained with hepatobiliary scintigraphy may be a good indicator of the volume of the gallbladder. The accuracy of GBEF was confirmed by comparison with 3D-CT examination. GBEF is considered a useful parameter of pathophysiological gallbladder function.

Adult↗

PubMed1997

Biodegradation of aniline, anthracene, chlornitrophen, fenitrothion and linear alkylbenzene sulphonate in pond water.

Biodegradation of five chemicals (aniline, anthracene, chlornitrophen (CNP), fenitrothion (FNT) and linear alkylbenzene sulphonate (LAS)) by aquatic bacteria in three different types of ponds was determined according to the cultivation method developed by this group. The degradability toward these chemicals was varied among the ponds, except for LAS which was decomposed well in all samples. Higher degradability towards the two agrochemicals, CNT and FNT, was found in the pond surrounded by paddy fields, whereas aniline and anthracene were decomposed more rapidly in the pond located in the industrial area. Water from the pond in the botanical garden, with the least exposure to any chemicals, exhibited the lowest degradation toward all chemicals tested. There was no significant seasonal variation in the biodegradation of chemicals in these ponds. It was deduced that biodegradability toward certain chemicals could be a result of acclimatization of the microbial community by chemical contamination present and past, suggesting the possible use of biodegradation profiles as an indicator for chemical pollution in the aquatic environment.

Biodegradation, Environmental↗

PubMed1997

Gas exchange function through the mastoid mucosa in ears after surgery.

Gas exchange function through the mastoid mucosa was investigated in ears after surgery using nitrous oxide. Increase in the mastoid pressure was assessed by a micropressure sensor placed in the mastoid cavity during the second-stage revision operation performed under general anesthesia using 67% nitrous oxide, 33% oxygen, and sevoflurane on 14 ears with chronic adhesive otitis media or cholesteatoma as well as on seven ears without inflammation as controls. All seven control ears showed pressure increase in the mastoid in various degrees. In the 14 postoperative ears, nine of the 10 ears on which the mastoid mucosa had previously been able to be preserved in various degrees showed pressure increase in the mastoid, but none of the remaining four ears, which had previously had mastoidectomy, showed any pressure increase. The presence or absence of the mastoid pressure increase of those ears was also found to be correlated well with the presence or absence of mastoid aeration on computed tomography examined just before the second-stage operation. These results appear to indicate that, in ears after surgery, recovery of both the gas exchange function and aeration in the mastoid is expected only when the mastoid mucosa can be preserved even partially.

Adolescent↗

PubMed1997

Comparison of surgical results of responders and non-responders to the prism adaptation test in intermittent exotropia.

The data for 94 consecutive patients with intermittent exotropia of basic type, ranging from 20 to 40 prism diopters (delta), who preoperatively wore neutralizing prisms for 3 to 5 days, were studied retrospectively. The surgery in 43 patients in whom the amount of increase of angle was 4delta or less was based on the original angle (Group A), while that in 51 patients in whom the magnitude of increase was 5delta or more was based on the increased angle of deviation (Group B). Patients with initial deviation less than 30delta and patients younger than 7 years of age showed an increase of deviation with prism correction. There were no significant differences in surgical results between the two groups at 1 year, and at 3 years; although at 3 years satisfactory motor alignment and binocular function for single vision at distance was higher in Group B than that in Group A.

Adaptation, Ocular↗

PubMed1997

Is mitomycin effective in preventing muscle migration after hang-back recession in a rabbit model?

To investigate the effect of intraoperative mitomycin C (MMC) application on muscle insertion migration after adjustable surgery, hang-back recession was bilaterally performed for 4 mm on the inferior rectus muscle in 30 rabbits. The scleral wound of the insertion site of one eye of each pair was treated with a sponge soaked with a solution cotaining mitomycin at a concentration of either 0.4 or 1.0 mg/ml for 5 min. As a control, the contralateral eye was treated with a distilled-water-soaked sponge. Three, 6 and 12 weeks later, the distance from the anterior border of the reattached muscle to the original insertion was measured with in vivo and microscopic examination. Anterior migration of the muscle insertion was observed in both the MMC-treated and control eye. The measurement by the in vivo and histologic examinations revealed that MMC treatment did not significantly reduce the anterior migration relative to the control eye. Analysis of the time course in the MMC-treated eye revealed a significant increase during the observation period in anterior migration as measured by the histologic examination (p = 0.0267 for the 0.4 mg/ml group and p = 0.0408 for the 1.0 mg/ml group). Exposure to MMC has no significant inhibitory effect on the muscle migration compared to that in the control eyes.

Animals↗

PubMed1997

Influence of the upper respiratory tract infection on tubal compliance in children with otitis media with effusion.

To clarify the influence of inflammation on tubal compliance in children with otitis media with effusion (OME), we investigated the change of compliance of the ET by upper respiratory tract infection (URTI) in 18 children (23 ears) with OME using the forced response test. The tubal compliance index (TCI), the ratio of passive tubal resistances at two different airflow rates, significantly increased during URTI represented by acute rhinitis or paranasal sinusitis in comparison with non-URTI periods (paired t-test: t = 4.14, p < 0.001). In nine ears, the TCI could be followed for some months after that, during which the children had had URTI several times. A clear reproducible correlation was found between the presence or absence of URTI and the TCI values; the TCI values increased again during URTI and decreased after the URTI periods. These results seemed to support our hypothesis that compliance of the ET may depend not only on the property of the cartilaginous framework of the ET but also upon the mucosal condition.

Child↗

PubMed1997

[Examination of scanning technique for lung cancer screening with helical CT].

As a new application of helical CT scanning we evaluated the parameters for lung cancer screening with an extremely low doses and large helical pitch. On the phantom studies, the image quality obtained with the low dose parameter was not inferior to that of the usual screening technique but artifacts were increased with the large helical pitch. A scanning technique using 120 kv, 40-60mA, 10mmth, 20mm/ sec, and a reconstruction pitch of 2 was used for lung cancer screening (screening parameters) (50 cases), and comparison was made between the detectability of the screening parameters and the routine parameters (120 kv, 200mA, 10mmth, 10-13mm/sec, and a reconstruction pitch of 1-1.3). Detectability with the screening parameters was as follows: nodular lesions (< 5mm in size: 76%. 5-10mm: 90-93% 10mm < 100%), linear lesions: 94-95%, infiltrations: 93-100%. There were no false negative lesions, when the reconstruction pitch of the screening parameters was changed from 1 to 0.25. In conclusion, reconstruction pitch had the most influence on lesion detectability.

Adult↗

PubMed1997

[Significant findings on CT performed before presence of post-surgical bowel obstruction].

We evaluated whether CT performed before the presence of bowel obstruction (pre-CT) is useful in predicting the presence of post-surgical bowel obstruction. Thirty-three patients with post-surgical bowel obstructions who had pre-CT were reviewed. The pre-CT findings were compared with the findings of CT performed after the presence of bowel obstruction (post-CT) in 16 patients, and with the intraoperative findings in 18 patients. Pre-CT demonstrated many interesting findings, such as a discrepancy in the caliber of the bowel, the presence of two adjacent collapsed loops, a beak-like appearance of the bowel, focal distention and/or wall thickness of bowel loops, and twisted mesentery. Twenty-three (70%) of 33 patients had one or more of these findings on pre-CT. All patients with a surgically proved closed loop obstruction had two adjacent collapsed loops on both pre- and post-CT. In six (86%) of seven patients who had focal dilated bowel loops and twelve (71%) of seventeen patients who had twisted mesentery on pre-CT, conservative management was proved ineffective. Pre-CT showed many significant findings. Attention should be paid to these findings, because they can predict the presence of post-surgical bowel obstruction. In particular, we stress that two adjacent collapsed loops on pre-CT is a sign of the presence of post-surgical closed loop obstruction.

Adult↗

PubMed1997

Identification of the anti-adhesive site buried within the heparin-binding domain of fibronectin.

We recently found that heparin-binding domain 2 (Hep 2) of fibronectin (FN) exhibits cryptic anti-adhesive activity. In order to locate the anti-adhesive site, a number of synthetic peptides which represents the primary structure of the Hep 2 domain were characterized as to their ability to decrease the adhesion of A375SM melanoma cells to FN substrate. Only one peptide (T-E-A-T-I-T-G-L-E-P-G-T-E-Y-T-I-Y-V-I-A-L, residues 1835-1855) (peptide III14-2), which is situated between the previously identified adhesive sites, FN-C/H-I and II, decreased the cell adhesion to FN. Assaying of the anti-adhesive activities of sub-peptides showed that the hydrophobic moiety of peptide III14-2 (underlined sequence) seems to be indispensable for the anti-adhesive activity. These results suggest that anti-adhesive activity is closely associated with the sequence, Y-T-I-V-I-A-L, that is usually buried within the Hep 2 domain structure because of its hydrophobic nature.

Amino Acid Sequence↗

PubMed1997

[Proposal on new formulas for renal depth in the technetium-99m-mercaptoacetyltriglycine (MAG3) scintigraphy].

UNLABELLED: Recently, camera-based techniques to measure effective renal plasma flow (ERPF) have become more popular than single plasma sample techniques because camera-based measurements avoid the necessity of delayed plasma samples and in vitro techniques. The measurements of ERPF are used to estimate the clearance of technetium-99m-mercaptoacetyltriglycine (MAG3). However, camera-based techniques are dependent on an accurate estimate of renal depth to correct for soft-tissue attenuation. Then, new formulas for renal depth correction of technetium-99m-MAG3 clearance in place of Tønnesen's, M. Ito's, K. Itoh's, and Taylor's methods were tried to establish in this paper. PATIENTS AND METHODS: Eleven hundred and seventy patients without any renal disease were objected. The data from measurement of renal depth using X-ray CT in supine position were analyzed statistically. RESULTS: The depths of right kidney (Dr) and left kidney (Dl) were 7.33 +/- 1.27 and 7.07 +/- 1.27 cm. The correlation coefficients between Dr and height (H) body weight (W), body surface area (BSA: W0.425 x H0.725 x 0.007184 m2), age, and abdominal thickness (Ta) were 0.275, 0.709, 0.615, 0.087, and 0.743. The correlation coefficients between Dl and H, W, BSA, age, and Ta were 0.269, 0.732, 0.629, 0.029, and 0.812. Ta had best correlation with both Dr and Dl. The calculation formulas for Dr and Dl using Ta were as follows: Dr = 0.32 x Ta + 0.87 cm, and Dl = 0.36 x Ta - 0.08 cm. On the other hand, the multiplex calculation formulas of Dr or Dl with H, W, and Ta were as follows: Dr = 0.18Ta + 8.54 x (W/H) + 0.75 (r = 0.768), and Dl = 0.26Ta + 5.90 x (W/H)-0.16 (r = 0.823). CONCLUSION: The new regression equations provide superior estimates of renal depth compared to conventional equations. Application of these new formulas into camera-based protocols to determine renal clearances may lead to more accurate measurements of ERPF using technetium-99m-MAG3 scintigraphy.

Adolescent↗