Impact of contrast-enhanced mammography in surgical management of breast cancers for women with dense breasts: a dual-center, multi-disciplinary study in Asia.

OBJECTIVE: To evaluate the impact of pre-operative contrast-enhanced mammography (CEM) in breast cancer patients with dense breasts. METHODS: We conducted a retrospective review of 232 histologically proven breast cancers in 200 women (mean age: 53.4 years ± 10.2) who underwent pre-surgical CEM imaging across two Asian institutions (Singapore and Taiwan). Majority (95.5%) of patients had dense breast tissue (BI-RADS category C or D). Surgical decision was recorded in a simulated blinded multi-disciplinary team setting on two separate scenarios: (i) pre-CEM setting with standard imaging, and clinical and histopathological results; and (ii) post-CEM setting with new imaging and corresponding histological findings from CEM. Alterations in surgical plan (if any) because of CEM imaging were recorded. Predictors CEM of patients who benefitted from surgical plan alterations were evaluated using logistic regression. RESULTS: CEM resulted in altered surgical plans in 36 (18%) of 200 patients in this study. CEM discovered clinically significant larger tumor size or extent in 24 (12%) patients and additional tumors in 12 (6%) patients. CEM also detected additional benign/false-positive lesions in 13 (6.5%) of the 200 patients. Significant predictors of patients who benefitted from surgical alterations found on multivariate analysis were pre-CEM surgical decision for upfront breast conservation (OR, 7.7; 95% CI, 1.9-32.1; p = 0.005), architectural distortion on mammograms (OR, 7.6; 95% CI, 1.3-42.9; p = .022), and tumor size of ≥ 1.5 cm (OR, 1.5; 95% CI, 1.0-2.2; p = .034). CONCLUSION: CEM is an effective imaging technique for pre-surgical planning for Asian breast cancer patients with dense breasts. KEY POINTS: • CEM significantly altered surgical plans in 18% (nearly 1 in 5) of this Asian study cohort with dense breasts. • Significant patient and imaging predictors for surgical plan alteration include (i) patients considered for upfront breast-conserving surgery; (ii) architectural distortion lesions; and (iii) tumor size of ≥ 1.5 cm. • Additional false-positive/benign lesions detected through CEM were uncommon, affecting only 6.5% of the study cohort.

Architecture distortion score (ADS) in malignancy risk stratification of architecture distortion on contrast-enhanced digital mammography.

OBJECTIVE: To develop a risk predictor model in evaluation of tomosynthesis-detected architectural distortion (AD) based on characteristics of contrast-enhanced digital mammography (CEDM). METHODS: Ninety-four AD lesions on CEDM in combination with tomosynthesis were retrospectively reviewed from 92 consecutive women (mean age, 52.4 years ± 7.9) with abnormal diagnostic or screening mammography. CEDM results were correlated with histology of ADs using cross-tabulation for statistical analysis. Predictors for risk of malignancy from CEDM characteristics (background parenchyma enhancement, degree of AD enhancement, enhancing morphology, size of enhancement, and enhancing spiculations) and patient's age were evaluated using logistic regression. We propose a sum score, termed AD score (ADS), for risk stratification and corresponding suggested BI-RADS category. RESULTS: Thirty-three of ninety-four (35.1%) of detected AD lesions were malignant. The sensitivity, specificity, PPV, and NPV of CEDM in evaluation of malignant AD are 100%, 42.6%, 48.5%, and 100%, respectively. Absence of AD enhancement on CEDM is highly indicative of no underlying malignancy. On multivariate analysis, the predictors on CEDM with statistical significance are (1) marked intensity of AD enhancement (OR, 22.6; 95%CI 3.1, 166.6; p = .002); and (2) presence of enhancing spiculations (OR, 9.1; 95%CI 2.2, 36.5; p = .002). A prediction model whose scores (ADS) given by ranking of OR of all predictors with AUC of 0.934 and Brier score of 0.0956 was developed. CONCLUSION: ADS-based lesion characterization on CEDM enables risk assessment of tomosynthesis-detected AD lesions. KEY POINTS: • Architecture distortions presenting with marked enhancement intensity and presence of enhancing spiculations are highly associated with risk of malignancy. • Absence of architecture distortion enhancement in minimal or mild background parenchyma enhancement on CEDM indicates low risk of breast malignancy (NPV = 100%).

Development of U-Net Breast Density Segmentation Method for Fat-Sat MR Images Using Transfer Learning Based on Non-Fat-Sat Model.

To develop a U-net deep learning method for breast tissue segmentation on fat-sat T1-weighted (T1W) MRI using transfer learning (TL) from a model developed for non-fat-sat images. The training dataset (N = 126) was imaged on a 1.5 T MR scanner, and the independent testing dataset (N = 40) was imaged on a 3 T scanner, both using fat-sat T1W pulse sequence. Pre-contrast images acquired in the dynamic-contrast-enhanced (DCE) MRI sequence were used for analysis. All patients had unilateral cancer, and the segmentation was performed using the contralateral normal breast. The ground truth of breast and fibroglandular tissue (FGT) segmentation was generated using a template-based segmentation method with a clustering algorithm. The deep learning segmentation was performed using U-net models trained with and without TL, by using initial values of trainable parameters taken from the previous model for non-fat-sat images. The ground truth of each case was used to evaluate the segmentation performance of the U-net models by calculating the dice similarity coefficient (DSC) and the overall accuracy based on all pixels. Pearson's correlation was used to evaluate the correlation of breast volume and FGT volume between the U-net prediction output and the ground truth. In the training dataset, the evaluation was performed using tenfold cross-validation, and the mean DSC with and without TL was 0.97 vs. 0.95 for breast and 0.86 vs. 0.80 for FGT. When the final model developed with and without TL from the training dataset was applied to the testing dataset, the mean DSC was 0.89 vs. 0.83 for breast and 0.81 vs. 0.81 for FGT, respectively. Application of TL not only improved the DSC, but also decreased the required training case number. Lastly, there was a high correlation (R2 > 0.90) for both the training and testing datasets between the U-net prediction output and ground truth for breast volume and FGT volume. U-net can be applied to perform breast tissue segmentation on fat-sat images, and TL is an efficient strategy to develop a specific model for each different dataset.

The Complication of Hepatic Artery Injuries of 1,304 Percutaneous Transhepatic Biliary Drainage in a Single Institute.

PURPOSE: To determine frequency of and assess risk factors for hepatic artery (HA) injury during percutaneous transhepatic biliary drainage (PTBD) and to discuss the technique and report the clinical outcome of embolization for HA injury. MATERIALS AND METHODS: Over a 14-year period (2002-2016), 1,304 PTBD procedures in 920 patients were recorded. The incidence of HA injury was determined, and possible associated risk factors were analyzed. When injury occurred, HA embolization was performed at the site as close to the bleeding point as possible. Clinical outcomes of these patients after embolization were reported. RESULTS: Of 1,304 PTBD procedures, a left-sided approach was used in 722 procedures (55.4%), and intrahepatic duct (IHD) puncture under ultrasound guidance was used in 1,161 procedures (90.1%). The IHD was nondilated in 124 (9.5%) patients. The punctured ductal entry site was peripheral in 1,181 (90.6%) patients. In this series, 8 procedures (0.61%) were complicated by HA injury. IHD dilatation status was the only risk factor (P = .017) for HA injury. Embolization was performed with technical and clinical success in all 8 patients. No recurrent hemobilia, intraabdominal bleeding, or other sequelae of HA injury after embolization was noted during 1 week to 84 months of follow-up. CONCLUSIONS: HA injury is a relatively rare complication of PTBD. IHD dilatation status was the only risk factor for HA injury in this study. When HA injury occurred, embolization therapy was effective in managing this complication.

Discriminating pyogenic brain abscesses, necrotic glioblastomas, and necrotic metastatic brain tumors by means of susceptibility-weighted imaging.

OBJECTIVES: To investigate the feasibility of using susceptibility-weighted imaging (SWI) to discriminate abscesses and necrotic tumours. METHODS: Twenty-one patients with pyogenic abscesses, 21 patients with rim-enhancing glioblastomas and 23 patients with rim-enhancing metastases underwent SWI. Intralesional susceptibility signal (ILSS) was analyzed employing both qualitative (QL) and semi-quantitative (SQ) methods. Logistic regression models and receiver operating characteristic analysis were used to demonstrate the discriminating power. RESULTS: In QL analysis, ILSSs were seen in 12 of 21 abscesses, in 20 of 21 glioblastomas, and in 16 of 23 metastases. In SQ analysis, a low degree of ILSS (85.8 %) was in the majority of abscesses and a high degree of ILSS (76.2 %) was in the majority of glioblastomas. SQ model was significantly better than QL model in distinguishing abscesses from glioblastomas (P < .001). A derived ILSS cutoff grade of 1 or less was quantified as having a sensitivity of 85.7 %, specificity of 90.5 %, accuracy of 88.1 %, PPV of 90.0 %, and NPV of 86.4 % in distinguishing abscesses from glioblastomas. CONCLUSIONS: A high-grade ILSS may help distinguish glioblastomas from abscesses and necrotic metastatic brain tumours. The lack of ILSS or low-grade ILSS can be a more specific sign in the imaging diagnosis of abscesses. KEY POINTS: • ILSS of SWI can contribute to differential diagnosis of rim-enhanced mass. • Low-grade ILSS can be a more specific sign in abscesses. • High-grade ILSS may help distinguish necrotic glioblastomas from abscesses. • ILSS spreads across the four ILSS categories in metastases.

Effects of quality assurance regulatory enforcement on performance of mammography systems: evidence from large-scale surveys in Taiwan.

OBJECTIVE: The Standards for Medical Exposure Quality Assurance in mammography systems were enacted on July 1, 2008, in Taiwan. This study aimed to evaluate the trends in performance of mammography units before and after the regulation started on the basis of annual on-site surveys from 2008 to 2010. MATERIALS AND METHODS: On-site measurements were conducted on 215, 205, and 209 mammography units in 2008, 2009, and 2010, respectively, which accounted for more than 95% of all units in Taiwan. Phantom image quality, average glandular dose (AGD), and half-value layer were evaluated on all systems. Processor conditions, compression conditions, radiation output, and computed radiography exposure indicators were assessed on units participating in mammography screening in 2008 and on all units in the later years. Evaluations of maximum compression force and automatic exposure control reproducibility were added into the protocol from 2009 onward. RESULTS: Mean phantom scores were improved significantly from 2008 to 2009 (11.63 ± 1.30 vs 12.31 ± 0.94, p < 0.05) and remained stable for 2010 (12.35 ± 0.87). Mean AGDs were 1.48 ± 0.47, 1.38 ± 0.41, and 1.37 ± 0.42 mGy over the 3 years, with a significant reduction from 2008 to 2009 (p < 0.05). For film-screen mammography systems, variations of sensitometric curves were greatly reduced in 2009 and 2010 when compared with 2008. Passing rates were increased after the regulation took effect in almost all aspects. CONCLUSION: Results from large-scale on-site surveys showed an overall improvement in performance after quality assurance in mammography was enforced in Taiwan.

Assessment of blood flow in hepatocellular carcinoma: correlations of computed tomography perfusion imaging and circulating angiogenic factors.

Hepatocellular carcinoma (HCC) is a highly vascular tumor through the process of angiogenesis. To evaluate more non-invasive techniques for assessment of blood flow (BF) in HCC, this study examined the relationships between BF of HCC measured by computer tomography (CT) perfusion imaging and four circulating angiogenic factors in HCC patients. Interleukin 6 (IL-6), interleukin 8 (IL-8), vascular endothelial growth factor (VEGF), and platelet derived growth factor (PDGF) in plasma were measured using Bio-Plex multiplex immunoassay in 21 HCC patients and eight healthy controls. Circulating IL-6, IL-8 and VEGF showed higher concentrations in HCC patients than in controls (p < 0.05), and predicted HCC occurrence better than chance (p < 0.01). Twenty-one patients with HCC received 21-phase liver imaging using a 64-slice CT. Total BF, arterial BF, portal BF, arterial fraction (arterial BF/total BF) of the HCC and surrounding liver parenchyma, and HCC-parenchyma ratio were measured using a dual-vessel model. After analyzing the correlations between BF in HCC and four circulating angiogenic factors, we found that the HCC-parenchyma ratio of arterial BF showed a significantly positive correlation with the level of circulating IL-8 (p < 0.05). This circulating biomarker, IL-8, provides a non-invasive tool for assessment of BF in HCC.

Differentiated epithelial- and mesenchymal-like phenotypes in subcutaneous mouse xenografts using diffusion weighted-magnetic resonance imaging.

Epithelial-mesenchymal transition (EMT) is important for tumor metastasis. Detection of EMT protein expression and observation of morphological changes are commonly used to identify EMT. Diffusion-weighted magnetic resonance imaging (DW-MRI) and measuring apparent diffusion coefficient (ADC) values are noninvasive techniques for characterizing tumor microenvironments. We investigated the difference in ADC values between epithelial- and mesenchymal-like subcutaneous mouse xenografted tumors using DW-MRI. Epithelial-like MM189 PB-Klf4 and BL322 PB-Klf4 cells were generated from tumor suppressive Kruppel-like factor 4 (Klf4)-expressing mesenchymal-like MM189 and BL322 cells. The ADC values of xenografted tumors from epithelial-like MM189 PB-Klf4 and BL322 PB-Klf4 were significantly lower than those from their mesenchymal-like counterparts (p < 0.05 and p < 0.01, respectively). Our results suggested that DW-MRI is a potential tool for observing mesenchymal- or epithelial-like characteristics of subcutaneous xenografted tumors.

Multilayer appearance on contrast-enhanced susceptibility-weighted images on patients with brain abscesses: Possible origins and effects of postprocessing.

PURPOSE: To demonstrate the presence of a multilayer appearance of the capsule on contrast-enhanced (CE) susceptibility-weighted imaging (SWI) in patients with pyogenic brain abscesses. Possible origins for the appearance and effects of postprocessing settings are discussed. MATERIALS AND METHODS: Fourteen patients with pyogenic brain abscesses underwent post gadolinium-enhanced SWI at 1.5 T. All SWI images were postprocessed with various filter and mask settings to compare the image appearance. Computer simulations using a paramagnetic spherical shell model were performed to verify the clinical findings. RESULTS: Pyogenic brain abscesses demonstrated a multilayer appearance with a darkened ring within the enhanced capsule on CE-SWI in all patients. The multilayer appearance was slice-orientation-dependent, decreased with larger widths of the high-pass filter, and increased with larger numbers of phase mask multiplication operations, consistently on both simulation results and the clinical images. CONCLUSION: CE-SWI shows the multilayer appearance of the capsule in pyogenic brain abscesses, which may arise from postprocessing procedures originally designed to enhance susceptibility contrast. Although SWI may provide additional information valuable in the diagnosis of pyogenic brain abscesses, image interpretation should be exercised with caution, particularly for CE-SWI.

CT of coronary heart disease: Part 2, Dual-phase MDCT evaluates late symptom recurrence in ST-segment elevation myocardial infarction patients after revascularization.

OBJECTIVE: The purpose of the study was to investigate dual-phase MDCT for assessing obstructive lesions and the extent and severity of the subtending myocardium at risk in patients presenting with chest pain syndromes 9 or more months after having undergone revascularization for the treatment of ST-segment elevation myocardial infarction (STEMI). MATERIALS AND METHODS: Dual-phase 64-MDCT was performed on 135 patients with recurring chest symptoms 9 months or more after revascularization (mean ± SD, 23 ± 11 months after index invasive angiogram for treatment of STEMI). Obstructive lesions (≥ 50% stenosis) were detected by MDCT angiography and the extent of myocardium at risk was detected by delayed phase 3D myocardium maps. A myocardium at-risk score based on MDCT findings was defined as the extent of myocardium at risk governed by the coronary lesion and weighted by lesion severity. Results were compared with stress-redistribution (201)Tl-SPECT and invasive angiography. RESULTS: In restenotic, new, progressive, and previously obstructive lesions that are not currently progressive, analysis of assessable segments (1966/2025, 97.1%) obtained true-positive detection rates of 88.1%, 88.6%, 82.9%, and 100%, respectively; false-negative detection rates were 5.3%, 1.6%, 2.9%, and 8.8%. In 124 patients (91.9%) in whom all segments were assessable, the MDCT-based myocardium at-risk score correlated with the SPECT-based summed difference score (SDS) (r = 0.841, p < 0.001). For detecting SPECT-based SDS ≥ 1 and SDS > 3, areas under the receiver operating characteristic curve for the MDCT-based myocardium at-risk score were 0.874 (95% CI, 0.805-0.942) and 0.938 (95% CI, 0.895-0.981), with optimal cutoff values of 2.68 and 5.01, respectively. CONCLUSION: Dual-phase MDCT is useful in detecting different patterns of obstructive lesions and the extent of myocardium at risk as an alternative for therapeutic planning in patients presenting with late symptoms after treatment for acute myocardial infarction.

Contrast-enhanced ultrasound features of breast capillary hemangioma: a case report and review of literature.

Breast capillary hemangioma is a rare benign vascular tumor. A 59-year-old asymptomatic woman underwent screening mammography and breast ultrasound. B-mode ultrasound revealed a lobulated, hypoechoic mass. Color Doppler ultrasound showed no intratumoral blood flow. Contrast-enhanced ultrasound (CEUS) revealed internal fast homogeneous contrast enhancement of the mass and persistent enhancement after 4 min. A 14-gauge core needle biopsy was then performed. The radiologic and pathologic appearances were concordant with breast capillary hemangioma. The ultrasonic manifestations of breast hemangioma may vary, and differentiation from other inflammatory diseases and malignancies is challenging. CEUS may help in observing the vascular characteristics of breast capillary hemangioma.

Endoscopic papillary large balloon dilation alone without sphincterotomy for the treatment of large common bile duct stones.

BACKGROUND: Lethal pancreatitis has been reported after treatment for common bile duct stones using small endoscopic papillary balloon dilation. METHODS: We retrospectively evaluated the safety and efficacy of using large balloon dilation alone without the use of sphincterotomy for the treatment of large common bile duct stones in Kaohsiung Veterans General Hospital. Success rate of stone clearance, procedure-related adverse events and incidents, frequency of mechanical lithotripsy use, and recurrent stones were recorded. RESULTS: A total of 247 patients were reviewed in the current study. The mean age of the patients was 71.2 years. Most of them had comorbidities. Mean stone size was 16.4 mm. Among the patients, 132 (53.4%) had an intact gallbladder and 121 (49%) had a juxtapapillary diverticulum. The mean size of dilating balloon used was 13.2 mm. The mean duration of the dilating procedure was 4.7 min. There were 39 (15.8%) patients required the help of mechanical lithotripsy while retrieving the stones. The final success rate of complete retrieval of stones was 92.7%. The rate of pancreatic duct enhancement was 26.7% (66/247). There were 3 (1.2%) adverse events and 6 (2.4%) intra-procedure bleeding incidents. All patients recovered completely after conservative and endoscopic treatment respectively, and no procedure-related mortality was noted. 172 patients had a follow-up duration of more than 6 months and among these, 25 patients had recurrent common bile duct stones. It was significantly correlated to the common bile duct size (p = 0.036) CONCLUSIONS: Endoscopic papillary large balloon dilation alone is simple, safe, and effective in dealing with large common bile duct stones in relatively aged and debilitated patients.

Single-dose time-resolved contrast enhanced hybrid MR angiography in diagnosis of peripheral arterial disease: compared with digital subtraction angiography.

PURPOSE: To prospectively study the diagnostic performance of hybrid single-dose contrast-enhanced MRA of peripheral arterial disease (PAD), with digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: Hybrid MRA, combining time resolved imaging of contrast kinetics and two-station bolus-chase sequences, of lower limb was performed in 31 PAD patients (21 men, 10 women; mean age, 72 years) with two separate gadobenate dimeglumine (8 mL) injections in each sequence. Two independent blinded readers analyzed the vascular stenosis (32 segments in each limb). Sensitivity, specificity, and accuracy in all vascular segments and segments below popliteal artery were calculated. Interobserver agreements on MRA and intermodality agreements between MRA and DSA were calculated by using k statistics. RESULTS: Sensitivity, specificity, and accuracy of the hybrid MRA with regard to hemodynamically significant stenosis in all vascular segments were 92%, 97%, and 95% for reader 1, and 90%, 92%, and 92%, for reader 2, respectively. The interobsever agreements on MRA were good (k = 0.77-0.74) for all-grade stenosis, and excellent (k = 0.82-0.81) for hemadynamically significant stenosis. The intermodality agreements are good to excellent (k = 0.73-0.94). CONCLUSION: Single-dose hybrid MRA is a safe and reliable noninvasive alternative to conventional DSA in the assessment of PAD patients.

Rapid induction of orthotopic hepatocellular carcinoma in immune-competent rats by non-invasive ultrasound-guided cells implantation.

BACKGROUND: The fact that prognoses remain poor in patients with advanced hepatocellular carcinoma highlights the demand for suitable animal models to facilitate the development of anti-cancer medications. This study employed a relatively non-invasive approach to establish an orthotopic hepatocellular carcinoma model in immune-competent rats. This was done by ultrasound-guided implantation of cancer cells and the model was used to evaluate the therapeutic efficacy of short-term and low-dose epirubicin chemotherapy. METHODS: Rat Novikoff hepatoma cells were injected percutaneously into the liver lobes of Sprague-Dawley rats under the guidance of high resolution ultrasound. The implantation rate and the correlation between dissected and ultrasound-measured tumor sizes were evaluated. A similar induction procedure was performed by means of laparotomy in a different group of rats. Pairs of tumor measurement were compared by ultrasound and computerized tomography scan. Rats with a successful establishment of the tumor were divided into the treatment (7-day low-dose epirubicin) group and the control group. The tumor sizes were non-invasively monitored by the same ultrasound machine. Blood and tumor tissues from tumor-bearing rats were examined by biochemical and histological analysis respectively. RESULTS: Ultrasound-guided implantation of Novikoff hepatoma cells led to the formation of orthotopic hepatocellular carcinoma in 60.4% (55/91) of the Sprague-Dawley rats. Moreover, tumor sizes measured by ultrasound significantly correlated with those measured by calipers after sacrificing the animals (P < 0.00001). The rate of tumor induction by ultrasound-guided implantation was comparable to that of laparotomy (55/91, 60.4% vs. 39/52, 75%) and no significant difference in sizes of tumor was noted between the two groups. There was a significant correlation in tumor size measurement by ultrasound and computerized tomography scan. In tumor-bearing rats, short-term and low-dose epirubicin chemotherapy caused a significant reduction in tumor growth, and was found to be associated with enhanced apoptosis and attenuated proliferation as well as a decrease in the microvessel density in tumors. CONCLUSIONS: Ultrasound-guided implantation of Novikoff hepatoma cells is an effective means of establishing orthotopic hepatocellular carcinoma in Sprague-Dawley rats. Short-term and low-dose epirubicin chemotherapy had perturbed tumor progression by inducing apoptosis and neovascularization blockade.

Kinetic patterns of benign and malignant breast lesions on contrast enhanced digital mammogram.

PURPOSE: To evaluate the kinetic patterns of benign and malignant breast lesions using contrast-enhanced digital mammogram (CEDM). METHODS: Women with suspicious breast lesions on mammography or ultrasound were enrolled. Single-view mediolateral oblique (MLO) CEDM of an affected breast was acquired at 2, 3, 4, 7, and 10 min after injection of contrast agent. Three readers visually and semi-quantitatively analyzed the enhancement of suspicious lesions. The kinetic pattern of each lesion was classified as persistent, plateau, or washout over two time intervals, 2-4 min and 2-10 min, by comparing the signal intensity at the first time interval with that at the second. RESULTS: There were 73 malignant and 75 benign lesions in 148 patients (mean age: 52 years). Benign and malignant breast lesions showed the highest signal intensity at 3 min and 2 min, respectively. Average areas under receiver operating characteristic (ROC) curve for diagnostic accuracy based on lesion enhancement at different time points were 0.73 at 2 min, 0.72 at 3 min, 0.69 at 4 min, 0.67 at 7 min, and 0.64 at 10 min. Diagnostic performance was significantly better at 2, 3, and 4 min than at 7 and 10 min (all p < 0.05). A washout kinetic pattern was significantly associated with malignant lesions at 2-4 min and 2-10 min frames according to two of the three readers' interpretations (all p ≤ 0.001). CONCLUSION: Applications of optimal time intervals and kinetic patterns show promise in differentiation of benign and malignant breast lesions on CEDM.

Percutaneous retrieval of dislodged central venous port catheter: experience of 25 patients in a single institute.

BACKGROUND: For a dislodged port catheter, percutaneous retrieval by using a loop snare or a basket is the standard technique, with high success. However, once a loop snare fails, the likelihood of success with other tools is considered low. PURPOSE: To report our experience of percutaneous retrieval of dislodged port catheters and to emphasize the usefulness of grasping forceps. MATERIAL AND METHODS: During a 6-year period, a total of 25 dislodged port catheters were retrieved in our institute. The interval between port catheter implantation and dislodged catheter retrieval was 3-85 months (mean 23 months). The time of delayed retrieval ranged from 3 to 604 days (mean 58 days). A loop snare or grasping forceps were used via either the femoral or jugular route. RESULTS: The prevalence of port catheter dislodgement was 0.4% in our institute. All dislodged port catheters were successfully removed, including four patients with delayed retrieval of more than 90 days. A loop snare was used in 20 patients, with technical success in 18. Grasping forceps were used in seven patients, all with success (including the two patients who failed by initial use of a loop snare). No procedure-related complications were encountered, except transient arrhythmia in four patients requiring no medication. CONCLUSION: Although the prevalence of port catheter dislodgement is low, percutaneous attempts at retrieval should be performed in all patients, even in chronic settings. A loop snare is the instrument of choice for retrieval. Grasping forceps can be used as an auxiliary instrument, especially in patients where a loop snare fails.

Diagnostic performance of MR imaging in the assessment of subchondral fractures in avascular necrosis of the femoral head.

OBJECTIVE: A prospective study was conducted to determine the accuracy of routine magnetic resonance (MR) imaging in correctly identifying subchondral fracture in avascular necrosis of the femoral head without apparent focal collapse on standard radiographs. MATERIALS AND METHODS: Spiral computed tomography (CT) with coronal and sagittal reformations and routine MR imaging with spin-echo T1WI and fat-suppressed spin-echo T2WI coronal, axial, and sagittal images were performed in 28 hips of 25 patients (M/F = 20:5; age 16-76 years) suffering from early-stage avascular necrosis of the femoral head on standard radiographs. The MR images were reviewed by a musculoskeletal radiologist and a general radiologist in blinded fashion. Using CT as the standard of reference, the accuracy of MR imaging in diagnosing subchondral fractures in avascular necrosis was evaluated. RESULTS: When the diagnoses of the two readers were compared with each other, only 16 of the 28 diagnoses (57.5%) agreed. Seventeen of the 28 MR imaging readings (60.7%) made by the musculoskeletal radiologist and 15 of the 28 (53.5%) made by the general radiologist agreed with those of the CT standard. False-positive diagnosis (that is, diagnosis of fracture when no fracture could be seen on CT) was more common than false-negative diagnosis. CONCLUSIONS: The accuracy of routine MR imaging in the evaluation of subchondral fracture is not satisfactory. False-positive diagnosis is not uncommon. Interpretation of routine MR imaging readout should be guarded.

Fluoroscopic guidance of retrograde exchange of ureteral stents in women.

OBJECTIVE: The purpose of this study was to review our experience with fluoroscopically guided retrograde exchange of ureteral stents in women. MATERIALS AND METHODS: During a 48-month period, 28 women (age range, 38-76 years) were referred to our department for retrograde exchange of a ureteral stent. The causes of urinary obstruction were tumor compression in 26 patients and benign fibrotic stricture in two patients. A large-diameter snare catheter (25-mm single loop or 18- to 35-mm triple loop) or a foreign body retrieval forceps (opening width, 11.3 mm) was used to grasp the bladder end of the stent under fluoroscopic guidance. The technique entailed replacement of a patent or occluded ureteral stent with a 0.035- or 0.018-inch guidewire with or without the aid of advancement of an angiographic sheath. RESULTS: A total of 54 ureteral stents were exchanged with a snare catheter in 42 cases or a forceps in 12 cases. One stent misplaced too far up the ureter was replaced successfully through antegrade percutaneous nephrostomy. Ten occluded stents, including one single-J stent, were managed with a 0.018-inch guidewire in three cases, advancement of an angiographic sheath over the occluded stent into the ureter in five cases, and recannulation of the ureteral orifice with a guidewire in two cases. No complications of massive hemorrhage, ureter perforation, or infection were encountered. CONCLUSION: With proper selection of a snare or forceps catheter, retrograde exchange of ureteral stents in women can be easily performed under fluoroscopic guidance with high technical success and a low complication rate.