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Biomedical subjects

S T Hahn

Publications and source records attributed to S T Hahn.

At least 19 recordsLinked to original sources
PubMed2004

Gallbladder wall thickening: MR imaging and pathologic correlation with emphasis on layered pattern.

The aim of this study was to correlate MR findings of gallbladder wall thickening with pathologic findings on the basis of the layered pattern and to evaluate the diagnostic value of MR imaging in gallbladder disease. We retrospectively evaluated the source images of HASTE sequences for MR cholangiography in 144 patients with gallbladder wall thickening. The layered pattern of thickened wall was classified into four patterns. Type 1 shows two layers with a thin hypointense inner layer and thick hyperintense outer layer. Type 2 has two layers of ill-defined margin. Type 3 shows multiple hyperintense cystic spaces in the wall. Type 4 shows diffuse nodular thickening without layering. MR findings of a layered pattern of thickened gallbladder were well correlated with histopathology. Chronic cholecystitis matched to type 1, acute cholecystitis corresponded to type 2, adenomyomatosis showed type 3, and the gallbladder carcinomas showed type 4. All four layered patterns were associated with PPV of 73% or greater, sensitivity of 92% or greater and specificity of 95% or greater. Our results indicate that MR findings of gallbladder wall thickening are characteristic in each entity and correlate well with pathologic findings. The classification of the layered pattern may be valuable for interpreting thickened gallbladder wall.

Adult↗
PubMed2004

Atypical manifestations of reversible posterior leukoencephalopathy syndrome: findings on diffusion imaging and ADC mapping.

Typically, reversible posterior leukoencephalopathy syndrome (RPLS) involves the parieto-occipital lobes. When regions of the brain other than the parieto-occipital lobes are predominantly involved, the syndrome can be called atypical RPLS. The purpose of this study is to find radiological and pathophysiological features of atypical RPLS by using diffusion-weighted imaging (D-WI). We retrospectively reviewed seven patients (two with eclampsia, one with cyclosporine neurotoxicity, and four with hypertensive encephalopathy) with atypical MR manifestations of RPLS. Changes in signal intensity on T2-weighted imaging (T2-WI) and D-WI, and ADC ratio, were analyzed. In patients with atypical manifestation of RPLS, high signal intensities on T2-WI were noted in the frontal lobe, basal ganglia, thalamus, brainstem, and subcortical white matter in regions other than the parieto-occipital lobes. These areas of increased signal intensities on T2-WI showed increased ADC values, representing vasogenic edema in all seven patients. This result should be very useful in differentiating atypical RPLS from other metabolic brain disorders that affect the same sites with cytotoxic edema.

Adult↗
PubMed2004

Re-circulation artefact at the carotid bulb can be differentiated from true stenosis.

Re-circulation artefact developing secondary to vortex flow at the bulb of the internal carotid artery is very difficult to distinguish from true stenotic defect on two-dimensional Fourier transformed time-of-flight magnetic resonance angiography (2D-FT TOF MRA). The purpose of our study is to identify appropriate distinguishing features of re-circulation artefact. We included 45 extracranial carotid arteries collected from 25 patients who underwent both 2D-FT TOF MRA and contrast medium based angiography. Review of the 45 vessels demonstrated re-circulation artefact in 21 vessels, true stenotic defect in 8 vessels, and no filling defect in 16 vessels on 2D-FT TOF MRA. We compared the findings of re-circulation artefact and true stenotic defect in 29 vessels excluding the 16 vessels without filling defect. The following were evaluated: (1) preservation of posterior wall contour; (2) marginal character of filling defect; (3) darkness of filling defect; (4) involvement of common carotid artery by filling defect; (5) size of filling defect. In four out of the five evaluated items, statistically significant difference was present between re-circulation artefact group and true stenotic defect group (p<0.01 in all four items, chi(2) analysis). Re-circulation artefact demonstrated the preservation of the posterior wall contour (19/21), ill-defined margin (19/21), less dark defect (18/21), and no involvement of the common carotid artery (19/21). On the contrary true stenotic defect demonstrated focal loss of posterior wall contour (8/8), sharp margin (8/8), dark defect (8/8), and involvement of common carotid artery (4/8). No significant difference was noted in the size of the defect between the two groups (p>0.05). The specificity of 2D-FT TOF MRA for carotid stenosis was markedly increased after application of above signs. These distinguishing signs are very helpful in differentiating re-circulation artefact from true stenotic defect.

Adult↗
PubMed2003

Diffusion-weighted MRI and ADC mapping in FK506 neurotoxicity.

FK506 is a newly developed potent immunosuppressant for preventing rejection after organ transplantation. However, FK506 can induce central nervous system toxicity. Until now the pathogenic mechanism of FK506 neurotoxicity was unclear. We report the findings of diffusion-weighted MRI and apparent diffusion coefficient (ADC) mapping of a FK506 neurotoxicity patient who showed increased signal intensities in both parieto-occipital lobes on T(2) weighted images, diffusion-weighted images and ADC maps. These findings suggest that a vasogenic oedema rather than a cytotoxic oedema may play a pivotal role in FK506 neurotoxicity pathogenesis.

Adult↗
PubMed2001

Intraarterial lidocaine administration for relief of pain resulting from transarterial chemoembolization of hepatocellular carcinoma: its effectiveness and optimal timing of administration.

PURPOSE: Patients undergoing transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) commonly have significant post-procedural abdominal pain necessitating narcotic administration. It is known that intraarterial administration of lidocaine is effective in controlling the pain during the procedure. However, optimum timing of the lidocaine administration is not precisely known. The purpose of this study was to assess the efficacy of intraarterial lidocaine administration for control of pain resulting from TACE and to evaluate the optimal timing of administration. METHODS: In a prospective trial, 113 consecutive patients with HCC who underwent TACE were classified into three groups: those who received a lidocaine bolus intraarterially immediately prior to TACE (group A, n = 30), those who received lidocaine immediately after TACE (group B, n = 46), and those who did not received lidocaine (group C, n = 37). Incidence and degree of post-procedural pain was assessed using a subjective method (visual analogue scales scored from 0 to 10) and an objective method (amount of post-procedural analgesics). RESULTS: The incidence of post-procedural pain in group A (16.7%) was significantly lower than that of group B (38.3%; p = 0.005). The mean pain score was 3.0 in group A and 4.8 and 3.1 in groups B and C, respectively. The mean dose of analgesic used after the procedure in group A (25.0 mg) was significantly lower than those in group B (52.9 mg) and group C (41.0 mg; p = 0.002). CONCLUSIONS: Pre-TACE intraarterial administration of lidocaine is much more effective than post-TACE administration in reducing the incidence and the severity of post-procedural pain. Furthermore, in order to reduce the incidence of post-procedural pain and dose of post-procedural analgesics, we recommend routine pre-TACE administration of lidocaine because post-procedural pain might developed even in patients who did not feel any pain during the TACE.

Abdominal Pain↗
PubMed2001

Characteristic MR findings of cervical pregnancy.

The aim of this study was to define the characteristic MR findings of cervical pregnancy. Twelve patients with cervical pregnancy underwent MRI because of difficulty in the diagnosis by ultrasonography, human chorionic gonadotropin assessment, and other clinical evaluations. The assessment of MRI included size and location of the lesion, margin, MR signal intensity, rim of low-signal intensity, enhancement pattern, appearance of enhancing solid component, parametrial change, endometrial change, pelvic fluid collection, and ovarian change. All cases showed ill-marginated mass with very heterogeneous signal intensity on T2-weighted images, irregular internal high-signal intensities on T1-weighted images, a partial or circumferential rim of low-signal intensity, dense irregular peripheral enhancement and enhancing papillary solid components with accompanying tubular signal voids, and variably increased parametrial vascularities. This heterogeneous hemorrhagic mass with densely enhancing papillary solid components may be the typical MR finding for cervical pregnancy. J. Magn. Reson. Imaging 2001;13:918-922.

Adult↗
PubMed2001

Oncogenic osteomalacia associated with soft tissue chondromyxoid fibroma.

Oncogenic osteomalacia is a rarely described clinical entity characterized by hypophosphatemia, phosphaturia, and a low concentration of 1,25-dihydroxyvitamin D(3). It is most often associated with benign mesenchymal tumor and can be cured with surgical removal of the tumor. In this paper, we present a case of oncogenic osteomalacia caused by chondromyxoid fibroma in the soft tissue of the sole of the foot in a 56-year-old woman.

Bone Neoplasms↗
PubMed2001

Magnetic resonance imaging of the bone marrow after bone marrow transplantation or immunosuppressive therapy in aplastic anemia.

To compare magnetic resonance (MR) images of the bone marrow (BM) after bone marrow transplantation or immunosuppressive therapy in patients with aplastic anemia (AA), MR imaging of BM was reviewed retrospectively in 16 patients (13 males and 3 females, mean age 26 yr) with AA who completely responded clinically after transplantation or immunosuppressive therapy. The signal intensity (SI) of BM was classified into four patterns according to the increasing amount of cellular marrow, i.e., pattern I to IV. SI of MR imaging of BM exhibited an increase of cellular marrows following both transplantation and immunosuppressive therapy. Of the eight patients on transplantation, the SI of the lumbar spinal BM was pattern III in two patients and IV in six on T1-weighted and short tau inversion recovery (STIR) images. In the eight patients with immunosuppressive therapy, the SI of the lumbar spinal BM was pattern II in one, III in five, and IV in two on T1-weighted images and pattern II in one, III in four, and IV in three on STIR images. SI on MR imaging of the lumbar spinal BM showed a more cellular pattern in patients on transplantation than in those on immunosuppressive therapy.

Adolescent↗
PubMed2000

An investigation of the biological activity of bullrout (Notesthes robusta) venom.

Bullrout envenomation is known to cause intense pain. Crude bullrout venom and venom fractions were assessed for protease, hyaluronidase, phospholipase and hemolytic activities, reactivity with stonefish antivenom, lethality to brine shrimp and ability to elicit pain in human subjects. Compared with venom obtained from frozen specimens, live fish venom-milking techniques rendered greater venom potency and improved storage characteristics. Although mild proteolytic and hemolytic activity was observed, crude venom demonstrated no hyaluronidase or phospholipase A2 activity, did not affect brine shrimp, or show antigenicity with stonefish antivenom. A single venom protein isolated from bullrout venom is attributed with causing pain in human subjects. The sensations elicited by this novel algesic protein are consistent with chemical stimulation of polymodal nociceptors.

Animals↗
PubMed2000

Hemostatic effect of glue-lipiodol mixture plugged in the needle tract after renal biopsies in a high-risk, anticoagulated rabbit model.

RATIONALE AND OBJECTIVES: To investigate the hemostatic effect of a glue-lipiodol mixture plugged immediately into the needle tract after renal biopsy of high-risk, anticoagulated rabbits by use of a large-core gun biopsy needle and the subsequent pathological changes of the biopsy tract. METHODS: Twenty-five rabbits weighing 2 kg were divided into five groups (five rabbits each) according to time of sacrifice at 0, 2, 4, 6, and 8 days after biopsy. After anesthesia was induced, both kidneys were exposed and a bolus of 100 U/kg heparin was administered intravenously. Blood sampling was done twice, once before and once after heparinization, and activated partial thromboplastin times were measured for each. Then renal biopsies were performed in 25 pairs of kidneys by using an 18-gauge automated biopsy gun. The glue-lipiodol mixture was not injected into the first biopsy sites (control). Immediately after the second biopsies were done, 0.5 mL of the glue-lipiodol mixture at a 1:3 ratio was plugged into the needle tract through the outer cannula while withdrawing it slowly. Bleeding times of the two biopsies of each pair of kidneys were measured. All rabbits were humanely killed at their previously scheduled times, and histopathological findings were evaluated for the presence of inflammation, necrosis, foreign body reaction, and fibrosis around the biopsy tract. All parameters were classified into four categories according to the degree of severity, from 0 to + + +. RESULTS: Twenty-five cases (100%) of the controls bled after the biopsies were performed. Four of them (16%) showed immediate, massive, pulsatile bleeding. In contrast, only 11 of 25 cases (44%) bled at the second biopsy (plugged) sites and only two of them (8%) showed pulsatile bleeding. Mean bleeding times were 228 seconds in controls and 26 seconds in the glue-lipiodol mixture-plugged sites (P < 0.000). Histopathological examination of the needle tract in the plugged group revealed mild inflammation in the 0- to 2-day groups and moderate inflammation and mild necrosis in the 4- and 6-day groups. In the 8-day group, inflammation was diminished and only mild fibrosis was noted. There was no foreign body reaction in any of the specimens of the plugged group. CONCLUSIONS: We conclude that a glue-lipiodol mixture, when used as a plug material for the renal biopsy tract, is an efficacious method of bleeding control that is associated with a low incidence of pathological alterations in an anticoagulated rabbit model, thus demonstrating its future potential for clinical application.

Animals↗
PubMed2000

MR characteristics of progressive massive fibrosis.

This study was performed to evaluate the static and dynamic magnetic resonance imaging (MRI) contrast enhancement pattern of progressive massive fibrosis (PMF) in coal workers' pneumoconiosis. Eighteen lesions in 12 patients were evaluated using a 1.5-T MR unit. T1-weighted FLASH images were obtained before and 0.5, 1, 2, 3, 4, 5, 7.5, 10, 12.5, and 15 minutes after injection of gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA; 0.1 mmol/kg). Imaging findings, the contrast enhancing pattern, enhancement time curve, and the contrast uptake equivalent (CE; mmol/L) were evaluated. On T1-weighted images, 14 lesions showed high signal intensity, and four showed low signal intensity. On T2-weighted images, all lesions were of low signal intensity and were indistinguishable from aerated lung parenchyma. After contrast infusion, all lesions except two enhanced markedly. The time enhancement curve showed a marked, gradual increase in signal intensity up to 3 minutes, a subtle increase in signal intensity up to 7.5 minutes, and then a plateau until 15 minutes after Gd-DTPA injection. Characteristic MR findings of PMF in coal workers' pneumoconiosis include T1 high signal intensity, T2 low signal intensity, and marked postinfusion enhancement. The time enhancement curve shows a marked, gradual increase of signal intensity up to 3 minutes and plateau up to 15 minutes.

Aged↗
PubMed1996

Adrenal paragonimiasis simulating adrenal tumor--a case report.

We describe a case of adrenal paragonimiasis with its computed tomographic and ultrasonographic findings. Computed tomogram showed a well enhancing oval mass at right adrenal gland and ultrasonogram showed a dumbbell-shaped hyperechoic mass saddling on the top of the right kidney. Surgical specimen was multicystic mass filled with creamy material.

Adrenal Gland Diseases↗
PubMed1992

Ciguatoxin-protein association in skeletal muscle of Spanish mackerel (Scomberomorus commersoni).

A study of soluble protein from skeletal muscle of Scomberomorus commersoni was undertaken to elucidate aspects of ciguatoxin (CTX) bioaccumulation in marine teleosts. Skeletal muscle tissue samples from toxic and non-toxic specimens were subjected to fractionation, centrifugation, (NH4)2SO4 precipitation and Sephacryl S-200 chromatography of soluble proteins. Toxicity associated with various fractions was assessed by mouse bioassay, and toxic and non-toxic soluble protein fractions were compared using SDS-PAGE. CTX eluted from Sephacryl S-200 with soluble proteins of apparent mol. wt between 35,500 and 59,500. The toxic eluate contained 1.4% of total sample protein and 15% of total sample toxicity, with an associated 7.2-fold increase in specific activity. SDS-PAGE comparisons show two protein bands in the 37,400 and 40,600 mol. wt range which appeared in toxic soluble protein fractions, but were not detectable in control (non-toxic) samples. These findings are interpreted as being consistent with the association of CTX with at least one monomeric soluble protein of 37,000 to 40,600 mol. wt from toxic S. commersoni skeletal muscle.

Animals↗
PubMed1991

Struma ovarii simulating a teratodermoid cyst. Computed tomographic findings in one case.

A case report is presented in which there were computed tomographic (CT) findings of struma ovarii (SO) simulating a teratodermoid cyst. The patient was a 73-year-old woman with a painful mass in the lower abdomen. CT revealed a large complex mass with multiple cystic and solid components. One of the cysts had fat-fluid level and minor calcification in the wall. The histological findings were struma ovarii. To our knowledge, these CT findings have not been described previously. Our case demonstrates the importance of including struma ovarii in the CT differential diagnosis of teratodermoid cysts.

Aged↗
PubMedDate not supplied

Carbon dioxide gas as a venous contrast agent to guide upper-arm insertion of central venous catheters.

PURPOSE: Evaluate in a prospective randomized study carbon dioxide (CO2) gas compared to iodinated contrast agent for image-guided placement of peripherally inserted central venous catheters (PICCs). METHODS: The upper-arm approach to the central vein was used for placement of PICCs in 74 patients requiring intermediate or long-term central venous access. Fluoroscopy was used to obtain venous access during peripheral injection of CO2 (n = 41) or low osmolar contrast material (Omnipaque 240 mgI/ml) (n = 33). RESULTS: Placement of PICCs was accomplished in 88% of the CO2 group and in 100% of the contrast group, with a mean venipuncture of two in both groups. Venous access was unsuccessful in five patients with CO2 due to a small vein, venous spasm, or technical failure. The mean and range of procedure times were 22.8 min (13-64 min) with CO2 and 23.2 min (12-60 min) with contrast material. The average and range of CO2 and nonionic contrast volumes injected during the procedure were 35.4 ml (5-300 ml) and 27.8 ml (8-120 ml), respectively. Vital signs and oxygen saturation did not change significantly during or after injection of CO2. There was no incidence of adverse reaction following CO2 injection. CONCLUSION: CO2 gas is a useful contrast agent to guide upper-arm insertion of PICCs and may be a safe alternative in patients with renal insufficiency and/or allergy to iodinated contrast material.

Adolescent↗