Clinical Results and Hematologic Predictors of Linear Accelerator-Based Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy for Brain Metastasis in Patients Aged 75 Years or Older: A Retrospective Study.

OBJECTIVE: This study aimed to evaluate prognostic factors including pre-radiosurgical blood count in elderly patients (EPs) with brain metastasis (BM) who were treated using linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. METHODS: Between January 2011 and November 2021, 101 consecutive EPs with BM were treated by LINAC-based SRS or fSRT using LINAC with a micro-multileaf collimator. EPs were defined as patients aged ≥75 years. RESULTS: The tumors originated from the lungs (n = 90; 89.1%), colon (n = 2; 2.0%), and others (n = 9; 8.8%) in these EPs. The median pretreatment Karnofsky Performance Status was 80 (range, 40-100). The median follow-up time was 10 months (range, 0-76), as was the median survival. The 6-month, 1-year, and 2-year survival in the EP group was 58.3%, 43.2%, and 28.5%, respectively. Freedom from local failure at 6 months and 1 and 2 years was 97%, 95%, and 91.5%, respectively. Freedom from distant failure at 6 months and 1 and 2 years in EPs was 70.6%, 59.4%, and 54.2%, respectively. A high neutrophil/lymphocyte ratio >5.33 was an unfavorable predictor of prognosis for EPs with BMs treated with SRS and fSRT (P < 0.001). In the EPs, the prognostic factors associated with prolonged survival in the Cox proportional hazards model were being female and a good pretreatment Karnofsky Performance Status. CONCLUSIONS: The findings of our study highlight the efficacy of LINAC-based SRS and fSRT with a micro-multileaf collimator in the treatment of EPs with BMs. Neutrophil/lymphocyte ratio can be an important factor in treatment decisions for EPs with BMs.

Long-Term Survival after Linac-Based Stereotactic Radiosurgery and Radiotherapy with a Micro-Multileaf Collimator for Brain Metastasis.

BACKGROUND: this study aimed to evaluate the prognostic factors associated with long-term survival after linear accelerator (linac)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator for brain metastasis (BM). METHODS: This single-center retrospective study included 226 consecutive patients with BM who were treated with linac-based SRS or fSRT with a micro-multileaf collimator between January 2011 and December 2018. Long-term survival (LTS) was defined as survival for more than 2 years after SRS/fSRT. RESULTS: The tumors originated from the lung (n = 189, 83.6%), breast (n = 11, 4.9%), colon (n = 9, 4.0%), stomach (n = 4, 1.8%), kidney (n = 3, 1.3%), esophagus (n = 3, 1.3%), and other regions (n = 7, 3.1%). The median pretreatment Karnofsky performance scale (KPS) score was 90 (range: 40-100). The median follow-up time was 13 (range: 0-120) months. Out of the 226 patients, 72 (31.8%) were categorized in the LTS group. The median survival time was 43 months and 13 months in the LTS group and in the entire cohort, respectively. The 3-year, 4-year, and 5-year survival rate in the LTS group was 59.1%, 49.6%, and 40.7%, respectively. Multivariate regression logistic analysis showed that female sex, a pre-treatment KPS score ≥ 80, and the absence of extracranial metastasis were associated with long-term survival. CONCLUSIONS: female sex, a favorable pre-treatment KPS score, and the absence of extracranial metastasis were associated with long-term survival in the current cohort of patients with BM.

Linac-based stereotactic radiosurgery and fractionated stereotactic radiotherapy with a micro-multileaf collimator for brain metastasis in the primary motor cortex.

This study aimed to assess the clinical outcomes of linear accelerators (linac)-based, stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator for brain metastasis in the primary motor cortex (BMPMC). Thirty-five consecutive patients with BMPMC who were treated by linac-based SRS or fSRT between January 2012 and March 2020 were analyzed. BMPMC was defined as a tumor located in the precentral gyrus on gadolinium-enhanced magnetic resonance imaging (MRI) and T2-weghted imaging (T2WI). In total, 35 patients with 37 metastases were analyzed. The median follow-up time was 13 (range: 1-97) months. The tumor volume was 0.05-26.5 (median: 0.62) cm3. All patients were treated with SRS or fSRT using 35 Gy with 7 Gy per fraction daily. The median survival time (MST) was 16.9 months. The pretreatment KPS and RPA class significantly differed in terms of MST on the log-rank tests. Seven symptomatic patients had hemiparesis before SRS or fSRT. All symptomatic patients, except one with facial paresis and one who died within 3 months, experienced improvement at a 3 month follow-up. None of the patients presented with persistent radiation injury at the final follow-up. Two patients presented with grade 3 radiation-related central nervous system necrosis, which was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. In BMPMC, SRS and fSRT had good tumor control and did not cause serious complications. Therefore, they are suitable treatment options with an acceptable safety profile.

Salvage Surgical Resection after Linac-Based Stereotactic Radiosurgery for Newly Diagnosed Brain Metastasis.

BACKGROUND: This study aimed to assess the clinical outcomes of salvage surgical resection (SSR) after stereotactic radiosurgery and fractionated stereotactic radiotherapy (SRS/fSRT) for newly diagnosed brain metastasis. METHODS: Between November 2009 and May 2020, 318 consecutive patients with 1114 brain metastases were treated with SRS/fSRT for newly diagnosed brain metastasis at our hospital. During this study period, 21 of 318 patients (6.6%) and 21 of 1114 brain metastases (1.9%) went on to receive SSR after SRS/fSRT. Three patients underwent multiple surgical resections. Twenty-one consecutive patients underwent twenty-four SSRs. RESULTS: The median time from initial SRS/fSRT to SSR was 14 months (range: 2-96 months). The median follow-up after SSR was 17 months (range: 2-78 months). The range of tumor volume at initial SRS/fSRT was 0.12-21.46 cm3 (median: 1.02 cm3). Histopathological diagnosis after SSR was recurrence in 15 cases, and radiation necrosis (RN) or cyst formation in 6 cases. The time from SRS/fSRT to SSR was shorter in the recurrence than in the RNs and cyst formation, but these differences did not reach statistical significance (p = 0.067). The median survival time from SSR and from initial SRS/fSRT was 17 and 74 months, respectively. The cases with recurrence had a shorter survival time from initial SRS/fSRT than those without recurrence (p = 0.061). CONCLUSIONS: The patients treated with SRS/fSRT for brain metastasis need long-term follow-up. SSR is a safe and effective treatment for the recurrence, RN, and cyst formation after SRS/fSRT for brain metastasis.

Clitoral metastasis from uterine cervical cancer: A case report and review of the literature.

A 81-year-old woman vaginal bleeding and vulvar pain. Pretreatment work-up revealed a 4.5 cm cervical cancer extended to the lower-third of the vagina and an isolated clitoral metastasis. The patient was treated with a multimodal treatment consisting with radiotherapy followed by clitoridectomy. She recovered uneventfully following the multimodal treatment, and is currently free of disease. Clitoral metastasis is extremely rare, however, this condition should be considered in cervical cancer patients during the pretreatment work-up or follow-up period, especially when patients complain of clitoral pain or enlargement.

Linac-based fractionated stereotactic radiotherapy with a micro-multileaf collimator for large brain metastasis unsuitable for surgical resection.

The aim of this study was to assess clinical outcomes using linac-based, fractionated, stereotactic radiotherapy (fSRT) with a micro-multileaf collimator for large brain metastasis (LBM) unsuitable for surgical resection. Between January 2009 and October 2018 we treated 21 patients with LBM using linac-based fSRT. LBM was defined as a tumor with ≥30 mm maximal diameter in gadolinium-enhanced magnetic resonance images. LBMs originated from the lung (n = 17, 81%), ovary (n = 2, 9.5%), rectum (n = 1, 4.8%) and esophagus (n = 1, 4.8%). The median pretreatment Karnofsky performance status was 50 (range: 50-80). Recursive partition analysis (RPA) was as follows: Classes 2 and 3 were 7 and 14 patients, respectively. The median follow-up was 5 months (range: 1-86 months). The range of tumor volume was 8.7-26.5 cm3 (median: 17.1 cm3). All patients were basically treated with 35Gy in 5 fractions, except in three cases. The progression-free survival was 3.0 months. The median survival time was 7.0 months. There was no permanent radiation injury in any of the patients. Radiation-caused central nervous system necrosis, according to the Common Terminology Criteria for Adverse Events version 4.0, occurred in one patient (grade 3). One patients received bevacizumab for radiation necrosis. Two patients underwent additional surgical resection due to local progression and cyst formation. For patients with LBM unsuitable for surgical resection, linac-based fSRT is a promising therapeutic alternative.

Linac-Based Fractionated Stereotactic Radiotherapy with a Micro-Multileaf Collimator for Brainstem Metastasis.

BACKGROUND: To assess the neuroimaging and clinical outcomes in patients with brainstem metastasis (BSM) treated with linac-based fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. METHODS: Between May 2007 and January 2017, 24 patients (15 male and 9 female) with BSM (25 lesions: midbrain, 10; pons, 13; and medulla oblongata, 2) were consecutively treated with linac-based fSRT. BSM originated from the lung (n = 18, 75.0%), colon (n = 3, 12.5%), and breast (n = 3, 12.5%). The median patient age was 67.0 (range: 42-80) years. Recursive partition analysis classified 2 patients as class I, 17 as class II, and 5 as class III. Overall survival was calculated using the Kaplan-Meier method. RESULTS: Tumor volume ranged from 0.01 to 7.49 cm3 (median: 0.233 cm3), and patients were treated with a dose of 24-40 Gy in 7-13 fractions. The median OS was 9 months after fSRT (95% confidence interval 4.104-13.896). Large tumor volume, presence of brainstem-related symptoms, poor pretreatment Karnofsky performance status, and recursive partition analysis class III were significantly associated with low overall survival. Tumor volume decreased in 18 metastatic lesions, remained stable in 6, and increased in 1. No patient exhibited permanent radiation injury. Grade 2 nausea and vomiting according to the Common Terminology Criteria for Adverse Events 4.0 occurred in 1 patient who received corticosteroids. CONCLUSIONS: Linac-based fSRT with a micro-multileaf collimator delivered in the doses of 24-40 Gy in 7-13 fractions is a safe and effective local therapy for patients with BSM.

Prognostic impact of underlying lung disease in pulmonary wedge resection for lung cancer.

BACKGROUND: Pulmonary wedge resection is an option for lung cancer patients with limited cardiopulmonary preservation. As the impact of underlying lung status on the prognosis of such patients remains unclear, we assessed this issue. METHODS: A total of 149 borderline surgical candidates with localized lung cancer who had undergone wedge resection were retrospectively investigated. Clinical variables related to perioperative morbidity, local control rate, and oncological outcomes based on underlying lung disease were analyzed. RESULTS: According to the risk analysis of postoperative complications, underlying lung disease did not influence the surgical morbidity. Postoperative recurrence occurred in 65 patients (locoregional recurrence in 36, distant metastasis in 12, and both simultaneously in 17). Multivariate analysis revealed that emphysema on computed tomography (CT) [hazard ratio (HR) 0.45; 95% confidence interval (CI) 0.21-0.99] was an independent indicator of locoregional recurrence. Forty-four patients died of lung cancer and 29 of other causes. Multivariate analysis demonstrated that interstitial lung disease on CT (HR 1.98; 95% CI 1.01-3.89) was a predictor of poor prognosis. CONCLUSION: Pulmonary wedge resection can be safely undergone by lung cancer patients regardless of pulmonary comorbidity, although underlying lung disease may influence the prognosis after wedge resection.

Clinical and pathological characteristics of surgically resected intrapulmonary lymph nodes: Can they be differentiated from other malignant nodules?

BACKGROUND: Intrapulmonary lymph nodes (IPLNs) are often recognized as sub-centimeter solid pulmonary nodules (SCPNs). The present study investigated their clinical and pathological characteristics to allow clinicians to distinguish them from malignant nodules. METHODS: Among 194 SCPNs surgically resected between 2006 and 2016, 26 IPLNs were investigated histopathologically. In addition, 145 resected malignant SCPNs were compared radiographically with the 26 IPLNs. RESULTS: Radiographically, most IPLNs were in a middle or lower lobe, and all lesions were within 20 mm of the visceral pleura. Enlargement was seen in one lesion. Three lesions demonstrated linear density contiguous to pleura (LD), and 13 lesions were adjacent to the peripheral pulmonary vein (APV). Microscopically, all IPLNs showed adjacency to pulmonary veins, 23 showed interlobular septa extending from the IPLN, and 18 were surrounded by a dilatated lymphoid channel. Radiographical findings of LD and APV were also seen in malignant SCPNs (LD, 12/145; APV, 25/145). Comparative analysis revealed that enlargement and APV were significant predictors differentiating IPLNs from malignant SCPNs. The sensitivity/specificity of enlargement and APV were 92%/92% and 17%/50%, respectively. CONCLUSIONS: IPLNs show typical high-resolution computed tomography findings that reflect their histopathological characteristics. Such findings help identify IPLNs prior to surgery. Specifically, enlargement and APV may differentiate IPLNs from malignant SCPNs. However, atypical cases are also possible, and radiological findings are not specific for differentiating IPLNs from malignant lesions. Thus, clinicians should consider surgical exploration when diagnosing SCPNs.

Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications.

Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases.

Quantitative lung perfused blood volume imaging on dual-energy CT: capability for quantitative assessment of disease severity in patients with acute pulmonary thromboembolism.

BACKGROUND: Regional iodine distribution assessment on dual-energy computed tomography (DECT) has been suggested as useful for management of acute pulmonary thromboembolism (APTE) patients. However, no reported studies have made a direct comparison between quantitatively assessed DECT and right-to-left ventricular (RV/LV) ratio on CT for differentiation of right heart dysfunction (RHD) from non-right heart dysfunction (NRHD) in APTE patients. PURPOSE: To determine the capability of DECT for differentiation of RHD from NRHD in APTE patients. MATERIAL AND METHODS: Thirteen APTE patients underwent DECT and echocardiography at onset of APTE. Patients were divided into RHD (n = 7) and NRHD (n = 6) groups based on echocardiography. A normalized lung perfused blood volume map was generated, and two kinds of overall perfusion (OP) index were determined, one placed over each lung field (OP index A) and as the average from six regions of interest (ROIs) placed over each lung field (OP index B). The heterogeneity index was also determined as the standard deviation for the six ROIs. RV/LV ratio evaluations were also performed. To assess differences between the two groups, each index was statistically compared with the Mann-Whitney U test. The receiver-operating curve-based positive test was then performed to determine the feasible threshold value for dividing patients into the two groups. Finally, differentiation capabilities of the indexes were compared using McNemar's test. RESULTS: Significant differences between the two groups were found for both OP indexes and RV/LV ratio (P < 0.05). For each of the feasible threshold values, accuracy of each OP index with and without RV/LV ratio was better than that of the RV/LV ratio. CONCLUSION: Quantitative DECT has good potential for differentiation of APTE patients with and without right heart dysfunction.

Dynamic contrast-enhanced CT and MRI for pulmonary nodule assessment.

OBJECTIVE: The purpose of this article is to review advanced imaging of pulmonary nodules, including pathologic and pharmacokinetic background, conventional contrast-enhanced CT and MRI assessment, dynamic contrast-enhanced CT and MRI techniques, and dual-source and area-detector CT systems for pulmonary nodule evaluation. CONCLUSION: Clinicians need to understand the underlying principles and pathologic and pharmacokinetic backgrounds of contrast-enhanced CT and MRI to further improve diagnostic performance. With adjustments in image acquisition and postprocessing, contrast-enhanced CT and MRI, especially the dynamic versions, can have enhanced clinical application for pulmonary nodules and expanded clinical relevance for other thoracic diseases.

Changes of tumor size and tumor contrast enhancement during radiotherapy for non-small-cell lung cancer may be suggestive of treatment response.

We evaluated sequential dynamic contrast-enhanced CT (DCE-CT) scans to assess the possibility of early prediction of treatment responses by quantifying the tumor size reduction and the change in tumor enhancement during and after a course of radiotherapy (RT). Thirty-nine patients with non-small-cell lung cancer were treated with RT for initial treatment. DCE-CT scan was performed within one week before the beginning of treatment, after 17 or 18 fractions (34 or 36 Gy), and 1 week and 1 month after the end of RT. The correlation between the relative decrease in tumor diameter and that in the attenuation value was evaluated. Nineteen patients were evaluated in this study. The median tumor size was 39.5 mm at the start of treatment, 30.8 mm at 34-36 Gy, and 16.1 mm 1 month after the end of RT. The relative decrease in tumor diameter at 34-36 Gy well correlated with that 1 month after treatment (r = 0.85, r: Pearson's correlation coefficient, p < 0.001). Relative change in the attenuation value at the rim of the tumor at 34-36 Gy did not significantly correlate with the change in tumor diameter 1 month after the completion of RT, but in the center of the tumor, the change of the attenuation value in the delayed phase correlated with the change in tumor diameter. The decrease of tumor diameter during RT may be predictive of treatment response. The relative change of tumor enhancement in the center of the tumor in the delayed phase correlated with tumor shrinkage 1 month after the completion of RT.

[Clinical analysis of eight patients with pulmonary toxocariasis].

We encountered 8 adult cases of pulmonary toxocariasis. Five were asymptomatic, 1 had transient chest pain, 1 suffered from arthralgia and migrating skin pain, and 1 had chest discomfort due to pneumothorax. Infection was associated with the consumption of raw liver with paratenic hosts in 5 patients. The cause was suspected to be contact with infected young dogs in 1 case and was undetermined in 2 cases. All 8 cases showed some abnormalities in their laboratory examination results including eosinophilia (>500/microl) and elevated IgE (>100 IU), and all had positive results in serological examinations for the larval excretory-secretory product of Toxocara canis. In 7 patients, excluding the patient with pneumothorax, chest computed tomography demonstrated multiple small pulmonary lesions, most of which were either nodules with halos, or ground-glass opacities. One patient recovered without medication, while the other 7 were treated with albendazole (ABZ) with good responses. Although the optimal duration of ABZ therapy has not been established, 4 weeks or longer seemed necessary to obtain a complete cure in pulmonary toxocariasis.

Prototype of foot-controlled image-scrolling device for the picture archiving and communication system display interface.

Our purpose was to produce a prototype of a foot-controlled image-scrolling device that will prevent work-related upper extremity complaints by radiologists. After foot-controlled image-scrolling devices were added to a picture archiving and communication system, 15 (83%) of 18 radiologists indicated that fatigue and pain in their upper extremities were diminished. Upon further production and implementation of this image-scrolling device in radiology clinics, the new interface may help to prevent work-related injuries in radiologists.

[A case of diverticular form type of congenital choledochal dilatation with anomalous arrangement of pancreaticobiliary duct].

We report a case of diverticular form type of congenital choledochal dilatation with anomalous arrangement of pancreaticobiliary duct and bile duct stone. The patient was a 63-year-old woman with the chief complaint of epigastralgia. Abdominal CT showed low density area suggesting cystic lesion at the region of pancreatic head. MRCP and ERCP revealed dilatation of the common bile duct in the multiple diverticular form with anomalous arrangement of pancreaticobiliary duct. A 2.0cm sized stone was also recognized in the dilated common bile duct. The patient underwent resection of gall bladder and dilated common bile duct, followed by hepatico-jejunostomy. Histological findings did not revealed malignant changes in the mucosa of both gall bladder and dilated common bile duct.

Ultrasound follow-up of infantile hypertrophic pyloric stenosis (IHPS) during conservative therapy: ultrasound findings as criteria for diagnosis and cure.

PURPOSE: During conservative therapy of infantile hypertrophic pyloric stenosis (IHPS) with atropine sulfate, there are many patients who do not achieve normal values of pyloric wall thickness and canal length even though they are clinically cured (vomiting has ceased); an objective criterion for cure has not yet been established. The aim of this study was to examine whether the appearance of pyloric wall stratification can be used as a criterion for cure. METHODS: Twenty infants with IHPS who were treated conservatively were enrolled. Two of them ultimately required surgery. Ultrasound examinations were done serially and the pyloric wall thickness and canal length were measured. The echogenicity of the pyloric wall and the presence of wall stratification were noted. RESULTS: On admission, all infants satisfied the ultrasound criteria for IHPS and had a heterogeneous pyloric wall without stratification. With conservative therapy, symptoms disappeared, the pyloric wall thickness and the canal length gradually decreased, the echogenicity gradually became homogeneous and hypoechoic, and wall stratification appeared (in most cases before the pyloric wall thickness and the canal length had normalized). The absence of wall stratification suggests that cellular interstitial changes, such as edema or inflammation, are present in the pyloric wall in the acute stage. CONCLUSION: Pyloric wall stratification was absent during the acute stage, but it appeared after initiation of treatment but before the pyloric wall thickness and the canal length had normalized. The presence of pyloric wall stratification can be used as a criterion for cure; the absence of wall stratification can be added to ultrasound diagnostic criteria for IHPS.

Genome sequence of the ultrasmall unicellular red alga Cyanidioschyzon merolae 10D.

Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. Here we report the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells.

[Mechanical properties of biliary metallic stents: an experimental comparison].

PURPOSE: To assess the physical properties of biliary self-expandable metallic stents. MATERIALS AND METHODS: Six different types of biliary self-expandable metallic stents (Wallstent, ZA stent, Accuflex, S.M.A.R.T. stent, Spiral Z stent, and NT stent) were evaluated for the flexibility, trackability, and resistance of stent release for the introducer, and for repulsion force, flexibility, radial force, radio-opacity, and kink resistance for the stent. RESULTS: The Wallstent showed the best repulsion force, radio-opacity, and kink- resistance, while the ZA stent showed the best flexibility and trackability of the introducer and better radial force and radio-opacity. Accuflex showed the least resistance during stent release and better flexibility and radial force. The S.M.A.R.T. stent showed the largest radial force, and the Spiral Z stent showed better trackability of the introducer and better radio-opacity. The NT stent seemed to require overall improvement. CONCLUSION: The Wallstent appears preferable for placement in the extrahepatic bile ducts. The ZA stent can be applied for various approaches, but placement in comparatively straight bile ducts is preferable. With the Accuflex, insertion through routes where an acute angle exists should be avoided. In addition, balloon expansion before or after stent placement is preferable. The S.M.A.R.T. stent is placed in straighter intrahepatic bile ducts, while the Spiral Z stent should be placed through a straight approach. Balloon expansion before or after stent placement is preferable for the NT stent. No stent exhibited all of the ideal properties required. These results may contribute to the selection of biliary metallic stents.