Embolic effects of superabsorbent polymer microspheres in rabbit renal model: comparison with tris-acryl gelatin microspheres and polyvinyl alcohol

PURPOSE: We have developed a spherical embolic agent, superabsorbent polymer microspheres (SAP-MS). The aim of this study was to examine the embolic effects of SAP-MS in comparison with polyvinyl alcohol (PVA) particles and tris-acryl gelatin microsphere (Embosphere Microsphere; EM) in a rabbit renal model. MATERIALS AND METHODS: The right kidneys of nine rabbits were embolized with the given agents: PVA (180-300 microm) (n=3), EM (100-300 microm) (n=3), and SAP-MS (106-150 microm) (n=3). The embolized kidneys were evaluated by angiography and histology after one week. RESULTS: Renal artery occlusion and prominent coagulative necrosis were confirmed regardless of agent. PVA aggregated in the proximal vessels with tiny fragments migrating into glomeruli. Both EM and SAP-MS traveled distally up to the interlobular artery level, and a single particle achieved cross-sectional vessel occlusion. SAP-MS was markedly swollen, deformed, and conformed to the vessel lumen compared with the constantly spherical EM. Mild perivascular reaction was seen with both microspheres. CONCLUSION: SAP-MS resulted in targeted end-organ infarction in the rabbit renal model and showed different mechanical properties from other agents.     

Magnetic resonance imaging-guided focused ultrasound ablation of uterine fibroids: early clinical experience

PURPOSE: The aim of this study was to assess the feasibility and effectiveness of magnetic resonance (MRI)-guided focused ultrasound (MRIgFUS) ablation for uterine fibroids and to identify the candidates for this treatment. MATERIALS AND METHODS: A total of 48 patients with a symptomatic uterine fibroid underwent MRIgFUS. The percent ablation volume was calculated, and the patients' characteristics and the MR imaging features of the fibroids that might predict the effect of this treatment were assessed. Changes in the symptoms related to the uterine fibroid were assessed at 6 and 12 months. RESULTS: The planned target zone were successfully treated in 32 patients with bulk-related and menstrual symptoms but unsuccessfully treated in the remaining 16 patients. These 16 patients were obese or their uterine fibroid showed heterogeneous high signal intensity on T2-weighted images. The 32 successfully treated patients were followed up for 6 months. At the 6-month follow-up, bulk-related and menstrual symptoms were diminished in 60% and 51% of patients, respectively. Among them, 17 patients were followed up for 12 months, and 9 of them who showed alleviation of bulk-related symptoms at 6 months had further improvement. The mean percent ablation volume of those nine patients was 51%. In 5 (33%) of the 15 patients with alleviation of menstrual symptoms at 6 months, the symptoms became worse at 12 months. There was a significant difference in the mean percent ablation volume between patients with alleviation of menstrual symptoms and those without (54% vs. 37%; P = 0.03). CONCLUSION: MRIgFUS ablation is a safe, effective treatment for nonobese patients with symptomatic fibroids that show low signal intensity on T2-weighted images. Ablation of more than 50% of the fibroid volume may be needed with a short-term follow-up.     

Detection of hypervascular hepatocellular carcinoma by dynamic magnetic resonance imaging with double-echo chemical shift in-phase and opposed-phase gradient echo technique: comparison with dynamic helical computed tomography imaging with double arterial phase

PURPOSE: The technique of double-echo chemical shift gradient echo magnetic resonance imaging (MRI) with the fast low-angle shot (double-echo FLASH) sequence provides in-phase and opposed-phase images in a single breath hold. The purpose of this study was to evaluate the efficacy of dynamic MRI with double-echo FLASH imaging for the detection of hypervascular hepatocellular carcinoma by comparing it with dynamic helical computed tomography (CT) imaging with double arterial phase. MATERIALS AND METHODS: Twenty-nine patients with 67 hypervascular hepatocellular carcinoma nodules who underwent both dynamic MRI with double-echo FLASH imaging (repetition time/echo time/flip angle: 160/3.6, 7.0/80 degrees ) and dynamic helical CT imaging with double arterial phase were enrolled in the study. For dynamic MRI, precontrast, arterial, portal venous, and equilibrium phase images were obtained before and approximately 19, 60, and 120 seconds, respectively, after intravenous injection of 0.1 mmol/kg of gadopentetate dimeglumine at a rate of 2 ml/s. For dynamic CT imaging, quadraphase images, including early arterial, late arterial, portal venous, and equilibrium phases, were obtained serially approximately 20, 30, 70, and 180 seconds, respectively, after intravenous administration of 2 ml/kg of 300 mgI/ml of nonionic contrast medium at a rate of 5 ml/s. Three masked observers independently interpreted images obtained with each technique in random order, separately and without patient identifiers. Sensitivity and positive predictive values as well as the area below the alternative-free response receiver operating characteristic curve (Az) for each imaging technique were calculated and compared statistically. RESULTS: Mean sensitivity and positive predictive values of MRI for hypervascular hepatocellular carcinoma were 48% and 94%, respectively, and those of CT imaging were 47% and 91%, respectively. In 11 (38%) of the 29 patients, at least one observer judged dynamic MRI to be superior, whereas in 5 patients (17%), dynamic CT was judged to be superior. There was no significant difference in the sensitivity and positive predictive values between these techniques (p > 0.05). There was no significant difference either in mean Az values between CT (0.55) and MRI (0.57) (p = 0.61). CONCLUSION: Dynamic MRI with double-echo FLASH imaging can detect hypervascular hepatocellular carcinoma as well as dynamic helical CT imaging with double arterial phase.     

A case of gastric duplication evaluated by gastric emptying scintigraphy

Gastric duplications are relatively rare, and communication with the gastric lumen is extremely rare. A 67-year-old man was referred to our hospital because of recurrence of epigastric pain and fullness. An upper gastrointestinal contrast study revealed a double compartment stomach, with gastric duplication starting at the esophagogastric junction outside the greater curvature. Computed tomography of the stomach with gastrografin as contrast demonstrated complete communication of the gastric duplication and primary stomach. The patient was diagnosed with complete gastric duplication. Gastric emptying scintigraphy with Tc-99m diethyltriamine pentaacetic acid was performed. Test meal entered the primary stomach and duplication cyst simultaneously, and radioactivity in the primary stomach decreased linearly and gastric emptying was not delayed. In the duplication cyst, about 70% of the food that entered the cyst once was immediately evacuated from it, but the remaining 30% remained in the cyst for a long time. Gastric emptying of the primary stomach was not affected by formation of the duplication cyst.     

A case of recurrent cholangitis after bile duct injury during laparoscopic cholecystectomy: Value of scintigraphy with Tc-99m GSA and hepatobiliary scintigraphy for indication of lobectomy

A 39-year-old woman with acute cholecystitis and gallstones underwent laparoscopic cholecystectomy. She suffered from recurrent episodes of cholangitis due to injury of the major bile ducts during laparoscopic cholecystectomy. Hepatobiliary scintigraphy with Tc-99m Sn-N-pyridoxyl-5-methyltryptophan was performed. Although normal bile excretion was found from the left hepatic duct to the percutaneous transhepatic biliary drainage (PTBD) tube, excretion from the right hepatic lobe was prolonged. Scintigraphy with Tc-99m diethylenetriaminepentaacetic acid-galactosyl human serum albumin demonstrated atrophy of the right hepatic lobe and enlargement of the left hepatic lobe. Cholangiography via the PTBD tube revealed complete obstruction of the left hepatico-jejunal anastomosis and could not enhance the right intrahepatic bile duct. A right hepatic lobectomy was performed because of the atrophy, glissonitis and the absence of an appropriate bile duct for reconstruction. Postoperatively she was active and exhibited no evidence of recurrent cholangitis.     

Evaluation of anterior talofibular ligament lesion using 3-dimensional computed tomography

OBJECTIVE: The aim of this study was to evaluate the applicability of 3-dimensional computed tomography (3D CT) imaging for the diagnosis of anterior talofibular ligament (ATFL) injury. METHODS: Six patients with lateral instability of ankle joint were examined with 3D CT preoperatively. Three patients had chronic ATFL tear, and the others had os subfibulare. 3D CT images were compared with magnetic resonance imaging and the operative findings. RESULTS: The ATFL in the uninvolved side could be depicted clearly by 3D CT in all patients. In patients with chronic ATFL tear, 3D CT could evaluate the condition of ATFL remnant much better than MRI. In patients with os subfibulare, the relationship between bone fragment and ATFL was clearly imaged in 3D CT. Surgical findings in all patients were correlated well with 3D CT. CONCLUSIONS: This study showed that 3D CT has the possibility of being a useful diagnostic tool for evaluation of ATFL lesion.     

Effect of age on the fractional anisotropy (FA) value of peripheral nerves and clinical significance of the age-corrected FA value for evaluating polyneuropathies

Introduction

We investigated the correlation between age and the fractional anisotropy (FA) values of peripheral nerves in healthy adults and compared the age-corrected FA values of peripheral nerves in healthy subjects and patients with polyneuropathy.

Methods

The institutional review board approved this study and informed consent was obtained from all participants before entry into the study. We optimized diffusion tensor imaging using a 3-T magnetic resonance scanner and an extremity coil for scanning tibial nerves. The effect of age and sex on the FA values of tibial nerves in healthy volunteers was investigated and the age-corrected FA values of tibial nerves in healthy volunteers and patients with polyneuropathy were compared.

Results

The maximum FA values of the tibial nerves remained constant until age 45 (approximately 0.516); they subsequently decreased by 0.004/year in healthy volunteers. After removing the effect of age with an age-adjusted equation, the median maximum FA values in the volunteers and patients were 0.518 (range, 0.406–0.616) and 0.442 (range, 0.376–0.530), respectively. The age-corrected FA values were significantly lower in the patients than the healthy volunteers (p?p?=?0.416).

Conclusion

The age-corrected FA value of the peripheral nerves helps to differentiate between age-related peripheral nerve degeneration and polyneuropathies.     

Determining the optimal timing for early arterial phase hepatic CT imaging by measuring abdominal aortic enhancement in variable contrast injection protocols

OBJECTIVE: To find the optimal scan timing for early arterial phase hepatic CT with adequate arterial enhancement after the aortic contrast arrival. METHODS: Sixty patients were divided randomly into three groups, each of which received 2.0 mL/kg of the 300 mgI/mL contrast medium with an injection duration of 30 seconds (Group A, mean rate 3.6 mL/sec); of 25 seconds (B, 4.6 mL/sec); of 30 seconds (3.6 mL/sec) followed by a saline chaser (C). RESULTS: After the contrast arrival, aortic enhancement increased rapidly for 6-15 seconds (mean, 10 seconds) to the initial peak enhancement in all groups, and then, increased moderately to the maximum aortic enhancement over the following 19, 13, and 21 seconds, respectively. The mean maximum aortic enhancement in Group B (392 HU) and C (360 HU) were significantly higher than that in A (326 HU), respectively. The difference between the initial and maximum aortic enhancement was less than 50 HU. CONCLUSION: The optimal timing of the early arterial phase for hepatic CT arteriography is 10-15 seconds after the aortic arrival.     

Design of a Novel Antimicrobial Peptide Activated by Virulent Proteases

Antimicrobial peptides are promising antibiotics as they possess strong antimicrobial activity and very broad spectra of activity. However, administration of an antibiotic with a very broad spectrum of activity disrupts normal microflora and increases the risks of other fatal infections. To solve the problem, we designed a novel antimicrobial peptide that is activated by virulent proteases of pathogenic organisms. We constructed a peptide composed of three domains, namely an antimicrobial peptide (lactoferricin) as the active center, a protective peptide (magainin intervening sequence) that suppresses antimicrobial activity, and a specific linker that joins these two components and is efficiently cleaved by virulent proteases. We utilized Candida albicans as a model organism that produces secreted aspartic proteases as a virulence attribute. We screened for a peptide sequence efficiently cleaved by secreted aspartic proteases isozymes and identified a GFIKAFPK peptide as the most favorable substrate. Subsequently, we chemically synthesized a peptide containing the GFIKAFPK sequence. The designed peptide possessed no antimicrobial activity until it was activated by secreted aspartic proteases isozymes. Furthermore, it demonstrated selective antimicrobial activity against C. albicans, but not against Saccharomyces cerevisiae. A designed peptide like the one described in this study may protect normal microflora, resulting in enhanced safety as a therapeutic.