Microfluidic fabrication of 6-methoxyethylamino numonafide-eluting magnetic microspheres.

Recently, 6-methoxyethylamino numonafide (MEAN) exhibited potent inhibition of hepatocellular carcinoma (HCC) cell growth and less systemic toxicity than amonafide. MEAN may serve as an ideal candidate for the treatment of HCC; however, liver-directed, selective infusion methods may be critical to maximize the MEAN dose delivered to the targeted tumors. This study describes the microfluidic fabrication of MEAN-eluting ultrasmall superparamagnetic iron oxide (USPIO) nanocluster-containing alginate microspheres (MEAN-magnetic microspheres) intended for selective transcatheter delivery to HCC. The resulting drug delivery platform was mono-disperse, microsphere sizes were readily controlled based on channel flow rates during synthesis procedures, and drug release rates from the microspheres could be readily controlled with the introduction of USPIO nanoclusters. The MR relaxivity properties of the microspheres suggest the feasibility of in vivo imaging after administration, and these microspheres exhibited potent therapeutic effects significantly inhibiting cell growth inducing apoptosis in hepatoma cells.

Effect of MR angiography on the diagnosis and treatment of patients with suspected renovascular disease.

PURPOSE: Although the diagnostic accuracy of renal magnetic resonance (MR) angiography is established, its effect on referring physicians is unknown. The authors prospectively measured the effect of MR angiography results on referring physicians' diagnosis and treatment (plans) of patients with suspected renovascular disease. MATERIALS AND METHODS: Referring physicians prospectively completed questionnaires before and after MR angiography was performed during evaluation of their patients with suspected renovascular disease. The questionnaires asked them to estimate the probability (0%-100%) of their most likely diagnosis before and after receiving the imaging information. They were also asked for their anticipated and final treatment plans. The authors calculated the mean gain in diagnostic percentage confidence and the proportion of patients with changed initial diagnoses or anticipated management. A paired t-test was used to assess significance of the gains in diagnostic percentage confidence. RESULTS: Physicians prospectively completed pre- and post-MR-angiography questionnaires for 30 patients. MR angiography improved mean diagnostic certainty by 35% (P < .0001). MR angiography changed physicians' initial diagnoses in 12 patients (40%). Anticipated treatment plans were changed in 20 patients (67%). Invasive procedures were avoided in eight patients (27%). CONCLUSION: MR angiography has a substantial effect on the diagnostic and therapeutic decision-making of physicians managing patients with suspected renovascular disease.

Aorta and runoff vessels: single-injection MR angiography with automated table movement compared with multiinjection time-resolved MR angiography--initial results.

The authors compared two techniques for performing runoff, contrast material-enhanced magnetic resonance (MR) angiography. Multiinjection time-resolved imaging of contrast kinetics (TRICKS) and single-injection bolus-chase MR angiographic examinations were performed in 10 volunteers and 10 patients. Image quality and venous overlay of the major blood vessels of the abdomen, thigh, and calf were evaluated. Significantly more (P <.05) vessels were depicted with diagnostic quality on multiinjection TRICKS than on single-injection bolus-chase MR angiographic images.

The vascular impact of uterine artery embolization: prospective sonographic assessment of ovarian arterial circulation.

PURPOSE: The etiology of premature ovarian failure after uterine artery embolization (UAE) is unknown. The authors prospectively assessed ovarian arterial circulation before and after UAE with use of ultrasonography (US). The authors hypothesize that nontarget embolization of the ovary occurs during routine UAE. MATERIALS AND METHODS: Twenty-three women (mean age of 42.6 years; range, 35-51 y) participated in the study. Grayscale, color, and pulsed-wave Doppler US studies were performed immediately before and after UAE. Resistive index (RI) and pulsatility index (PI) were calculated. The proportion of women who developed increased vascular impedance after UAE was statistically assessed with use of the Yates-corrected chi(2) test. RESULTS: Seventeen of 23 patients (74%) completed the study. Nine of 17 (54%) showed complete loss of ovarian arterial perfusion after UAE. Six of 17 (35%) had increases in RI and PI, whereas two of 17 (11%) had decreases in RI and PI. The increase in vascular impedance after UAE in 15 of 17 patients was significant (P <.0001). CONCLUSION: Loss of detectable ovarian arterial perfusion occurs in the majority of patients undergoing UAE. Ovarian vascular impedance increases in nearly all patients as a result of UAE. The authors conclude that inadvertent nontarget embolization of the ovarian arterial bed occurs during routine UAE.

Determination of optimal injection parameters for intraarterial gadolinium-enhanced MR angiography.

PURPOSE: Rapid vascular depiction with use of a minimum of gadolinium (Gd) contrast agent will be required to generate road-map vascular images for magnetic resonance (MR) imaging-guided endovascular interventions. The objective of this study was to optimize intraarterial injections of MR contrast agent during magnetic resonance angiography (MRA), obtained during interventions, by determining the optimal Gd vascular concentration ([Gd]) for vessel depiction. MATERIALS AND METHODS: The authors derived theoretical expressions to estimate the [Gd] resulting in maximal signal in blood. A model was developed to account for flow dilution to estimate [Gd] given the injected Gd concentration, injection rate, and the blood flow rate. Experiments in four animals (three dogs, one pig) were conducted to verify this model with use of both time-resolved two-dimensional (2D) thick-slab and single-phase three-dimensional (3D) MRA acquisitions. The authors also determined the optimal [Gd] required for vessel depiction in animal models. RESULTS: The theoretical expressions yielded optimal [Gd] of 10.2 mmol/L in blood. The animal experiments used the flow dilution model and examined signal enhancement in the aorta and the renal and iliac arteries. Maximal enhancement occurred at [Gd] = 16.2 +/- 4.0 mmol/L (mean +/- SE). CONCLUSIONS: The theoretically predicted values for [Gd]optimal and the flow dilution model were successfully validated. The relationship between injected [Gd], injection rate, and blood flow rate permits rapid intraarterial administration of contrast material, using less overall contrast material than with standard intravenous Gd-enhanced MRA.

Impact of MR angiography on the diagnosis and management of renal transplant dysfunction.

PURPOSE: To evaluate the impact of magnetic resonance angiography (MRA) on referring physicians' diagnoses and treatment of patients with renal transplant dysfunction. MATERIALS AND METHODS: Physicians of the renal transplant service at the authors' university hospital prospectively completed questionnaires before and after MRA was performed in the evaluation of renal transplants. The questionnaires asked physicians to estimate the probability (0%-100%) of their most likely diagnosis before and after receiving the imaging information. They were also asked to provide their anticipated and final treatment plans. The authors calculated the mean gain in diagnostic percentage confidence and the proportion of patients with changed initial diagnoses or anticipated management. A paired t test was used to assess statistical significance of the gains in diagnostic percentage confidence. RESULTS: Pre-MRA and post-MRA questionnaires were prospectively completed on 31 separate patients. The mean gain in diagnostic certainty percentage from MRA was 33% (95% CI, 19%-51%; P < .001). MRA changed physicians' initial diagnoses in 20 patients (65%; 95% CI, 47%-79%). Immediate clinical management changed in 16 patients (52%; 95% CI, 35%-68%). Invasive procedures were avoided in 12 patients (39%). CONCLUSION: MRA has considerable impact on referring physicians' diagnoses and treatment of patients with suspected renal allograft dysfunction.

Real-time MR imaging-guided passive catheter tracking with use of gadolinium-filled catheters.

PURPOSE: To test the hypothesis that real-time magnetic resonance (MR) imaging-guided passive catheter tracking is feasible with use of dilute gadolinium (Gd)-filled catheters, to determine the optimal Gd concentration required for tracking, and to measure catheter tip tracking accuracy. MATERIALS AND METHODS: The authors tested a real-time, T1-weighted, two-dimensional, spoiled gradient-recalled echo MR imaging sequence suitable for tracking catheters. In a yogurt phantom, the authors placed 5-F catheters filled with 2%-12% Gd solutions. MR imaging was performed with and without use of a projection dephaser that suppressed background signal. The authors measured signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and enhancement ratio to determine the optimal Gd concentration for catheter depiction. Catheter tip tracking accuracy was measured in an acrylic phantom with use of linear regression analysis, with goodness of fit assessed statistically with the F test. RESULTS: Peak catheter SNR, CNR, and enhancement ratios were obtained with 4%-6% Gd concentrations. Tip tracking accuracy was determined to be +/- 0.41 mm (R2 = 0.99; P < .0001). MR imaging reconstructions were displayed up to 3.1 frames/sec. CONCLUSIONS: Accurate MR imaging-guided passive catheter tracking was feasible in real-time with use of dilute Gd-filled catheters. This technique may have application in MR imaging-guided endovascular procedures.

Treatment of stomal variceal hemorrhage with TIPS: case report and review of the literature.

We report a case in which recurrent hemorrhage from stomal varices was successfully treated by placement of a TIPS in a patient with prior colectomy for inflammatory bowel disease. Although several treatment options have been reported for this entity we believe that TIPS offers minimally invasive and definitive treatment.

The impact of uterine fibroid embolization on resumption of menses and ovarian function.

PURPOSE: To evaluate the effect of uterine fibroid embolization (UFE) on menstruation and ovarian function. METHODS: The authors performed an observational study of UFE for the treatment of symptomatic fibroids. All patients had regular predictable menses before intervention and none had clinical or laboratory findings of menopause. UFE was performed with use of standard methods with 355-700-microm-diameter polyvinyl alcohol (PVA) foam particles. The incidence of ovarian failure was calculated for women younger than 45 years and for those 45 years or older, based on retrospective stratification by age. The authors assessed statistical differences in ovarian failure between the two age groups with use of the X2 test. RESULTS: Sixty-six premenopausal women (age range, 30-55 years) underwent bilateral UFE and were followed for an average of 21 weeks (range, 12-77 weeks). In 56 of 66 (85%) patients, regular menses resumed after an average of 3.5 (range, 1-8) weeks. In 10 of 66 (15%) patients, regular menses did not resume. Clinical and biochemical findings consistent with ovarian failure and presumed menopause were seen in nine of 10 patients without resumption of menses (14% of total patients). Ovarian failure occurred in nine of 21 (43%) women older than 45 years and in none of the 45 women younger than 45 years (P < .05). There were no differences in presenting symptoms, amount of PVA used, or fibroid size between patients who did and did not resume menses. CONCLUSION: The majority of patients undergoing UFE will have resumption of menses, but the incidence of postprocedure ovarian failure is considerably higher than reported to date. Loss of menses induced by UFE is significantly more likely to occur in women older than 45 years.

MR-guided angioplasty of renal artery stenosis in a pig model: a feasibility study.

PURPOSE: To test the hypothesis that magnetic resonance (MR) imaging can guide the percutaneous treatment of renal artery stenosis in a pig model. MATERIALS AND METHODS: Ameroid constrictors were surgically placed around six renal arteries in four pigs. After 30-36 days, all stenoses were documented by conventional x-ray aortograms. MR-guided renal angioplasty was attempted for three stenoses. For these pigs, MR angiography was performed with use of contrast-enhanced three-dimensional (3D) techniques. The authors visualized catheters by filling them with dilute 4% gadolinium and imaging with two-dimensional (2D) and 3D MR fast spoiled gradient recalled echo techniques. Under MR guidance, the authors advanced a selective catheter into the affected renal artery and crossed the stenosis with a nitinol guide wire. Angioplasty was performed with a balloon catheter filled with dilute gadolinium. Stenosis and luminal diameter measurements were compared before and after angioplasty. RESULTS: After ameroid constrictor placement, four significant stenoses, one mild stenosis, and one occlusion developed. Under MR guidance, the authors achieved technical success in performing three of three (100%) attempted dilations. After MR-guided angioplasty, the mean reduction in stenosis was 35% and the mean increase in luminal diameter was 1.6 mm. CONCLUSION: Use of MR guidance for the angioplasty of renal artery stenosis in pigs is feasible.

Intraarterial gadolinium-enhanced 2D and 3D MR angiography: a preliminary study.

PURPOSE: To evaluate, in phantom and canine models, intraarterial gadolinium-enhanced two-dimensional (2D) and three-dimensional (3D) magnetic resonance angiography (MRA). MATERIALS AND METHODS: The in vitro experiments examined gadodiamide solutions ranging in gadolinium (Gd) concentration from 0.1% to 100%. A spoiled gradient-recalled echo (SPGR) sequence was used with various repetition time/echo time (TR/TE) parameters. Signal was measured to determine which concentration yielded the highest signal. For in vivo experiments, pigtail catheters were placed in the abdominal aortae of two dogs. Intraarterial injections of 20-30 mL of 0.5%-25% Gd solutions were performed. We acquired images with use of 2D and 3D SPGR techniques. Depiction of the abdominal aortae and renal vessels was assessed qualitatively and quantitatively. RESULTS: Phantom experiments demonstrated that a 2%-6% solution of Gd produced the highest MR signal, depending on the imaging parameters. In the canine model, a 2% Gd solution was best for 2D techniques, whereas 7%-14% Gd solutions were optimal for 3D techniques. CONCLUSIONS: Intraarterial contrast material-enhanced 2D and 3D MRA can be successfully implemented with use of dilute Gd. Dilution permits the administration of more intraarterial injections per day, without exceeding the dose limit, compared with intravenous Gd-enhanced MRA. Intraarterial injections also limit scan synchronization and contrast material dispersion issues. This technique may have application in MR-guided endovascular procedures.

Peripherally inserted central catheters: guidance with use of US versus venography in 2,650 patients.

PURPOSE: To compare technical success and initial complication rates of peripherally inserted central catheters (PICCs) by interventional radiologists using ultrasound (US) or venographic guidance. MATERIALS AND METHODS: With use of a computer database, the authors retrospectively reviewed 2,650 procedures, 2,126 of which were performed with US and 524 with venography. Technical success was defined as placement of a PICC. Initial complications were defined as development of a hematoma, inadvertent arterial puncture, or neuropathy. Statistical significance was assessed using the chi2 test. RESULTS: During 33 consecutive months, 2,650 procedures were performed with a complication rate of 1.0%. The technical success rate was 95.8% for venography and 99.6% for US. The initial complication rate was 0.75% for venography and 1.08% for US. There was no statistically significant difference in immediate complication rates (P = .50); however, there is statistical significance in regard to technical success (P < .001). CONCLUSION: There is no difference in initial complication rates when comparing US and venographic guidance for PICC insertion. The decision to use either method can be based on clinical grounds and/or physician preference, although US has a higher initial success rate.

The impact of sonography on the diagnosis of scrotal disorders.

PURPOSE: We assessed the impact of ultrasound on the referring urologist diagnosis of scrotal disorders. MATERIALS AND METHODS: University urologists (6 attending and 3 resident physicians) in a clinic setting completed questionnaires before and after on 35 patients with scrotal symptoms. The physicians were requested to estimate the probability (0 to 100%) of their most likely diagnosis before and after receiving the sonographic information. We calculated the mean change in diagnostic percentage confidence and also the proportion of patients whose pre-sonographic diagnosis was changed. RESULTS: Scrotal ultrasound changed the initial diagnosis in 11 of 35 patients (32%, 95% confidence interval 19 to 49). The mean percentage gain in diagnostic certainty from ultrasound was 29% (95% confidence interval 20 to 39, p < 0.001). CONCLUSIONS: Scrotal ultrasound has considerable impact on referring urologist diagnosis of scrotal abnormalities.

Evaluation of a turkey-breast phantom for teaching freehand, US-guided core-needle breast biopsy.

RATIONALE AND OBJECTIVES: Use of a turkey-breast phantom for developing freehand ultrasound (US)-guided core-needle biopsy skills was evaluated. MATERIALS AND METHODS: Thirteen diagnostic radiology trainees with varied experience in freehand US-guided breast core-needle biopsy were given instruction and allowed to practice the technique in a turkey-breast phantom. Three attempts were made before and after instruction and practice, and a questionnaire regarding experience, confidence, and anxiety was administered after these attempts. Technique, accuracy, and completion time were evaluated. RESULTS: Confidence related to procedure performance increased (P < .01), but the change in anxiety was not statistically significant. Accuracy improved, with the target being obtained in 87% of passes performed after instruction and practice versus 56% initially. Difficulty with visualizing the core needle sonographically during phantom biopsy decreased from 49% to 5% of attempts. Needle positioning perpendicular to the chest wall was observed initially in 38% of passes but was not observed after instruction and practice. There was no statistically significant change in time to complete biopsy. CONCLUSION: For teaching US-guided breast core-needle biopsy, use of a turkey-breast phantom helps improve technique, accuracy, and confidence of diagnostic radiology trainees.

Clinical value of renovascular resistive index measurement in the diagnosis of acute obstructive uropathy.

PURPOSE: We evaluated the clinical use of the renal resistive index in identifying patients with acute urinary tract obstruction. MATERIALS AND METHODS: Of 54 patients with suspected acute urinary tract obstruction who underwent measurements of renal resistive index 19 had unilateral obstruction documented with excretory urography and comprise our study sample. The contralateral nonobstructed kidneys served as controls. Criteria for obstruction were a resistive index of 0.70 or greater or a side to side difference of 0.10 or greater. We calculated sensitivity, specificity, and positive and negative predictive values. RESULTS: Sensitivity for obstruction was 42% with 11 false-positive cases, specificity was 79%, and positive and negative predictive values were 67 and 57%, respectively. CONCLUSIONS: Renal resistive index measurements are not valuable in detecting acute urinary tract obstruction.

Acute knee trauma: how many plain film views are necessary for the initial examination?

OBJECTIVE: To determine whether anteroposterior (AP) and lateral views of the knee are equivalent to four views in acute fracture detection. DESIGN: Three musculoskeletal radiologists retrospectively interpreted the plain film knee examinations of each patient, establishing ground truth for the presence or absence of a fracture. Cases were presented to four masked senior radiology residents twice--once as a two-view study and again as a four-view study--with 4 weeks separating the two reading sessions to minimize recall bias. Sensitivity, specificity, and diagnostic performance were calculated. PATIENTS: Ninety-two patients presenting to the emergency department with acute knee trauma were evaluated with at least a four-view plain film examination. RESULTS AND CONCLUSIONS: Mean sensitivity for fracture detection using four views (85%) was significantly higher than that using two views (79%). Mean specificity and receiver operating characteristic curve areas were not significantly different using two or four views. Four views are more sensitive than AP and lateral views alone in detection of acute knee fracture.

The impact of ankle radiographs on the diagnosis and management of acute ankle injuries.

RATIONALE AND OBJECTIVES: We assessed the impact of ankle radiographs on referring physicians' diagnoses and treatment of acute ankle injuries. METHODS: Twenty emergency department physicians prospectively completed questionnaires before and after radiography on 101 patients with acute trauma receiving ankle radiographs. The questionnaires asked physicians to estimate the probability (0-100%) of their most likely diagnosis before and after receiving the radiographic information. We also asked their anticipated and final treatment plans. We calculated the mean gain in diagnostic confidence percentage and the proportion of patients with changed initial diagnoses or anticipated management. RESULTS: The mean gain in diagnostic certainty from ankle radiographs was 34% (95% confidence interval [CI] = 28-40%). Ankle radiographs changed physicians' initial diagnoses in 37% (95% CI = 28-47%) of the patients. Immediate clinical management changed in 30% (95% CI = 22-40%) of the patients. CONCLUSION: Plain ankle radiographs have considerable impact on referring physicians' diagnoses and treatment of acute ankle trauma.