Quantitative assessment of renal obstruction in multi-phase CTU using automatic 3D segmentation of the renal parenchyma and renal pelvis: A proof of concept.

Purpose: Quantitative evaluation of renal obstruction is crucial for preventing renal atrophy. This study presents a novel method for diagnosing renal obstruction by automatically extracting objective indicators from routine multi-phase CT Urography (CTU). Material and methods: The study included multi-phase CTU examinations of 6 hydronephrotic kidneys and 24 non-hydronephrotic kidneys (23,164 slices). The developed algorithm segmented the renal parenchyma and the renal pelvis of each kidney in each CTU slice. Following a 3D reconstruction of the parenchyma and renal pelvis, the algorithm evaluated the amount of the contrast media in both components in each phase. Finally, the algorithm evaluated two indicators for assessing renal obstruction: the change in the total amount of contrast media in both components during the CTU phases, and the drainage time, "T1/2", from the renal parenchyma. Results: The algorithm segmented the parenchyma and renal pelvis with an average dice coefficient of 0.97 and 0.92 respectively. In all the hydronephrotic kidneys the total amount of contrast media did not decrease during the CTU examination and the T1/2 value was longer than 20 min. Both indicators yielded a statistically significant difference (p < 0.001) between hydronephrotic and normal kidneys, and combining both indicators yielded 100% accuracy. Conclusions: The novel algorithm enables accurate 3D segmentation of the renal parenchyma and pelvis and estimates the amount of contrast media in multi-phase CTU examinations. This serves as a proof-of-concept for the ability to extract from routine CTU indicators that alert to the presence of renal obstruction and estimate its severity.

In vivo noninvasive three-dimensional (3D) assessment of microwave thermal ablation zone using non-contrast-enhanced x-ray CT.

PURPOSE: To develop an image processing methodology for noninvasive three-dimensional (3D) quantification of microwave thermal ablation zones in vivo using x-ray computed tomography (CT) imaging without injection of a contrast enhancing material. METHODS: Six microwave (MW) thermal ablation procedures were performed in three pigs. The ablations were performed with a constant heating duration of 8 min and power level of 30 W. During the procedure images from sixty 1 mm thick slices were acquired every 30 s. At the end of all ablation procedures for each pig, a contrast-enhanced scan was acquired for reference. Special algorithms for addressing challenges stemming from the 3D in vivo setup and processing the acquired images were prepared. The algorithms first rearranged the data to account for the oblique needle orientation and for breathing motion. Then, the gray level variance changes were analyzed, and optical flow analysis was applied to the treated volume in order to obtain the ablation contours and reconstruct the ablation zone in 3D. The analysis also included a special correction algorithm for eliminating artifacts caused by proximal major blood vessels and blood flow. Finally, 3D reference reconstructions from the contrast-enhanced scan were obtained for quantitative comparison. RESULTS: For four ablations located >3 mm from a large blood vessel, the mean dice similarity coefficient (DSC) and the mean absolute radial discrepancy between the contours obtained from the reference contrast-enhanced images and the contours produced by the algorithm were 0.82 ± 0.03 and 1.92 ± 1.47 mm, respectively. In two cases of ablation adjacent to large blood vessels, the average DSC and discrepancy were: 0.67 ± 0.6 and 2.96 ± 2.15 mm, respectively. The addition of the special correction algorithm utilizing blood vessels mapping improved the mean DSC and the mean absolute discrepancy to 0.85 ± 0.02 and 1.19 ± 1.00 mm, respectively. CONCLUSIONS: The developed algorithms provide highly accurate detailed contours in vivo (average error < 2.5 mm) and cope well with the challenges listed above. Clinical implementation of the developed methodology could potentially provide real time noninvasive 3D accurate monitoring of MW thermal ablation in-vivo, provided that the radiation dose can be reduced.

Cost-effectiveness of baseline low-dose computed tomography screening for lung cancer: the Israeli experience.

OBJECTIVE: Reduced mortality with low-dose computed tomography (LDCT) lung cancer screening was demonstrated in a large randomized controlled study of high-risk individuals. Cost-effectiveness must be assessed before routine LDCT screening is considered. We aimed to evaluate the cost-effectiveness of LDCT lung cancer screening in Israel. METHODS: A decision analytic framework was used to evaluate the decision to screen or not screen from the health system perspective. The screening arm included 842 moderate-to-heavy smokers aged 45 years or older, screened at Hadassah-Hebrew University Medical Center from 1998 to 2004. In the usual-care arm, stage distribution and stage-specific life expectancy were obtained from the Israel National Cancer Registry data for 1994 to 2006. Lifetime stage-specific costs were estimated from medical records of patients diagnosed and treated at Hadassah Medical Center in the period 2003 to 2004. The analysis considered possible biases-lead time, overdiagnosis, and self-selection. Cost per quality-adjusted-life-year (QALY) gained by screening was estimated. RESULTS: Base-case incremental cost per QALY gained was $1464 (2011 prices). Extensive sensitivity analysis affirmed the low cost per QALY gained. The cost per QALY gained is lower than $10,000 with probability 0.937 and is lower than $20,000 with probability 0.978. CONCLUSIONS: Our analysis suggests that baseline LDCT lung cancer screening in Israel presents a good value for the money and should be considered for inclusion in the National List of Health Services financed publicly.

Evaluation of an electromagnetic image-fusion navigation system for biopsy of small lesions: assessment of accuracy in an in vivo swine model.

PURPOSE: To evaluate the accuracy of a novel combined electromagnetic (EM) navigation/image fusion system for biopsy of small lesions. MATERIALS AND METHODS: Using ultrasound (US) guidance, metallic (2 × 1 mm) targets were imbedded in the paraspinal muscle (n = 28), kidney (n = 18), and liver (n = 4) of four 55- to 65-kg pigs. Baseline helical computed tomography (CT) imaging (Brilliance; Philips) identified these biopsy targets and six and nine cutaneous fiducial markers. CT data were imported into a MyLab Twice system (Esaote, Genoa, Italy) for CT/US image fusion. After verification of successful image fusion, baseline registration error and respiratory motion error were assessed by documenting deviation of the US and CT position of the targets in real time. Biopsy targeting was subsequently performed under conditions of normal respiratory using 15-cm 16G eTrax needles (Civco). To mimic the conditions of poor US visualization, only reconstructed CT information was displayed during biopsy. Accuracy of targeting was measured by repeat CT scanning as the distance of the needle tip to the target center. Targeting accuracy of free-hand vs. guided technique, and electromagnetic (EM) sensor positioning (ie, on the hub or within the needle stylus tip) were evaluated. RESULTS: In muscle, needle registration error was 0.9 ± 1.2 mm and respiratory motion error 4.0 ± 1.0 mm. Target accuracy was 4.0 ± 3.2 mm when an EM sensor was imbedded in the needle tip. Yet, with the EM sensor back on the needle hub, greater targeting accuracy was achieved using an US guide (3.2 ± 1.6 mm) vs. freehand (5.7 ± 3.2 mm, P = .04). For kidney, registration error was 1.8 ± 1.7 mm and respiratory motion error 4.9 ± 1.0 mm. For the deeper kidney targets, target accuracy was 4.4 ± 3.2 mm with a tip EM sensor, which was an improvement over the hub EM sensor positioning (9.3 ± 4.6 mm; P < .01). An additional source of fusion error was noted for liver. Beyond 17 ± 1 mm of respiratory motion, targets were observed to move >3 cm with US transducer/needle compression resulting in 14 ± 1.4 mm targeting accuracy. CONCLUSIONS: A combined image-fusion/EM tracking platform can provide a high degree of needle placement accuracy (<5 mm) when targeting small lesions. Results fall within accuracy of respiratory error; with best results obtained by incorporating an EM sensor into the tip of the biopsy system.

Quality initiatives: quality improvement grand rounds at Beth Israel Deaconess Medical Center: CT colonography performance review after an adverse event.

As computed tomographic (CT) colonography is being used increasingly in clinical practice, an effective quality improvement process must be ensured. The quality improvement process is outlined for the reader by using an adverse event during CT colonography as an example. Components of this process are the approach to a sentinel event, performance of a root cause analysis, and development of strategies for minimizing errors after a serious adverse event. Important factors include indications and contraindications for the examination, proper imaging technique, training of personnel, complications of the procedure, and legal implications. Complications from CT colonography are rare. Attention must be paid to the correct technique for colonic insufflation, particularly in older patients and those who are symptomatic. Root cause analysis provides valuable tools for identification and implementation of improvements designed to avoid similar and other adverse events and to minimize damage.

Is coronary stent assessment improved with spectral analysis of dual energy CT?

RATIONALE AND OBJECTIVES: The aims of this study were to distinguish stents from iodinated contrast on the basis of spectral characteristics on dual-energy computed tomographic (DECT) imaging and to determine whether DECT imaging might provide a more accurate measurement of true stent lumen. MATERIALS AND METHODS: Three stainless steel stents and one cobalt chromium stent were scanned using a multidetector, single-source DECT scanner. Stents 2.5, 3.5, and 4.0 mm in diameter were filled with iodinated contrast, submerged in water, and scanned. Spectral analysis was performed to assess the separation of stents from iodinated contrast. Two independent reviewers measured stent lumen diameter and strut thickness on low-energy (L(0)), high-energy (L(1)), and combined-energy (L(c)) images. Dual-energy full-width half-maximum edge detection analysis was used to provide an independent assessment of stent luminal diameter and strut thickness. RESULTS: Two-dimensional graphical plots of computed tomographic attenuation for the L(0) and L(1) images did not demonstrate a sharp separation between the absorption characteristics of stents and iodinated contrast material. Stent lumens were underestimated by approximately 50% on L(c) images. Observer measurements on L(1) images demonstrated a 24% decrease in strut thickness and a 25% increase in stent luminal diameter compared to L(0) images (P < .0001). Full-width half-maximum measurements did not demonstrate significant changes in stent luminal diameters or strut thicknesses between L(0) and L(1) images. CONCLUSIONS: Spectral analysis did not clearly distinguish stents from iodinated contrast with the DECT system used in this study. The larger stent lumens visualized by the high-energy components of the x-ray spectrum were not related to improved computed tomographic delineation of stent thickness.

The effect of the cryosurgical cox-maze procedure on pulmonary veins diameter and left atrial size: computed tomography angiographic assessment.

OBJECTIVE: : The Cox-Maze procedure using cryoablation results in transmural lesions, which follow the lesion pattern of the cut-and-sew Cox-Maze procedure. The purpose of our study was to evaluate the effect of the Cox-Maze procedure on left atrial and pulmonary vein size using computed tomography angiogram (CTA). An additional aim was to evaluate pulmonary vein anatomic variability. METHODS: : Six patients (four women and two men; ages 39-63 years, mean age 54.3) underwent chest CTA 1 day before and 38 to 104 days (mean 62.6 days) after the cryosurgical Cox-Maze procedure. Measurements of pulmonary vein ostia and left atrial cranio-caudal, left-to-right and anterior-posterior diameters were derived by consensus. The change in diameters after therapy was compared using the Wilcoxon nonparametric test for paired measurements. Four patients (1 woman and 3 men; age 57-73 years; mean age 59) were evaluated with postoperative CTA alone 296-530 days (mean 447) after surgery, for the development of postoperative pulmonary vein stenosis. A single patient underwent preoperative CTA, but surgery was not performed. Pulmonary venous anatomy was recorded in all 11 patients. RESULTS: : Sinus rhythm was restored in all operated patients. No focal ostial stenosis of the pulmonary veins was observed. The quantitative assessment in the six patients with preoperative and postoperative studies disclosed only slight changes in pulmonary vein diameter with either reduction or dilatation of no more than 20% from baseline (P > 0.05). There was a consistent trend toward decrease in left atrial dimensions, which did not reach statistical significance. Six patients (55%) had standard pulmonary venous anatomy and five patients (45%) had at least one variation in their pulmonary vein anatomy. CONCLUSIONS: : In this study, we found that a very intensive cryoablation protocol around the pulmonary veins did not result in pulmonary vein stenosis. In addition, a relatively high incidence of anatomic variations of the pulmonary veins was documented.

Managing an acute adverse event in a radiology department.

Many local and national regulatory organizations require that all serious adverse events be promptly investigated, managed, and reported, with the first goal being to institute actions to prevent or minimize the occurrence of similar events. However, the tools and processes necessary for effective incident review and management have been developed largely by industrial organizations, and radiologists may not be familiar with such processes. Data analysis requires a root cause analysis to identify all possible active and latent contributors to the event, as well as the use of algorithms to determine the degree of responsibility when human error is implicated. Acceptable corrective actions that are reasonable, achievable, and measurable should be instituted. These changes should be monitored according to defined timelines by a designated person. In some cases, additional training or even remediation may be required. Subsequently, the focus should be on actively managing and improving error detection and reporting systems, as well as on seeking strategies for minimizing the occurrence of preventable errors.

Implementation of online radiology quality assurance reporting system for performance improvement: initial evaluation.

PURPOSE: To evaluate an online system developed and implemented for reporting and managing quality assurance (QA) events occurring in a radiology department. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval; informed consent was not required. Using repeated plan-do-study-act cycles, a radiology quality management team applied a 10-step process to implement an online reporting system. The system permits remote submission of cases by staff members. The number of weekly submissions to the system over a 9-month period was evaluated and compared with that for the preceding 6 months by using the Mann-Whitney test. Sources and nature of data, actions initiated, and final outcomes were also analyzed. Recorded data included forum of discussion, dimension of care, action items, monitoring of follow-up and compliance, and notification status. RESULTS: During the first 9 months of implementation, 605 cases were submitted (mean, 21.4 cases per week), a significant increase (P < .005) compared with the preceding 6 months (mean, 3.2 cases per week). Cases, which were submitted by residents (121 cases [20.0%]), fellows (94 cases [15.5%]), faculty members (319 cases [52.7%]), or technologists (54 cases [8.9%]), reported technical (33.1%) or administrative (8.0%) issues. The 329 clinical cases (54.4%) included 60 errors in communication (18.2%), 67 errors in interpretation (20.4%), 78 diagnostic delays (23.7%), 99 missed diagnoses (30.1%), and 54 procedural complications (16.4%); some cases were in more than one category. Twenty-three cases (3.8%) resulted in submission-related QA projects, and 69 cases (11.4%) resulted in individuals or sections of the hospital undergoing additional training. CONCLUSION: A secure online QA reporting system promotes reporting of QA events and serves as a database for identifying and managing trends, initiating performance improvement projects, and providing feedback to staff members who submit cases.

Colonic perforation at CT colonography: assessment of risk in a multicenter large cohort.

PURPOSE: To assess retrospectively the incidence, clinical features, and treatment of colonic perforation at computed tomographic (CT) colonography in a large multicenter cohort. MATERIALS AND METHODS: The study was performed in accordance with the institutional ethics committees' requirements of a retrospective review in each of the participating centers, and no informed consent was required. A review of all patients who underwent CT colonography between January 2001 and December 2004 in 11 medical centers representing more than 95% of studies performed in a single country was performed to determine the rate of colorectal perforation. Data about patient demographics and patient- and procedure-related risk were recorded. Information about the location of the perforation, its likely mechanism, and treatment was collected. Analysis included calculation of rates of colonic perforation and surgical treatment and of 95% confidence intervals. RESULTS: A total of 11 870 CT colonographic studies were performed in 6837 (57.6%) men and 5033 (42.4%) women (mean age, 59.9 years; range, 38-90 years) with seven cases of colorectal perforation, yielding a risk rate of 0.059% (one of 1696 studies; 95% confidence interval: one of 974, 971 of 6537). The mean age of the patients with perforation was 77.8 years. Six (84%) of seven cases of perforation occurred in symptomatic patients at high risk for colorectal neoplasia, and one (16%) occurred in an asymptomatic average-risk patient. All studies were performed after insufflation of room air. Six (84%) cases of perforation occurred in patients in whom a rectal tube was inserted, and in five of them, a balloon was inflated. Five (71%) cases of perforation occurred in the sigmoid colon; and two (29%), in the rectum. Four (57%) patients (one in 2968 patients; 95% confidence interval: 1.5 in 10 000, 14.7 in 10 000) required surgical treatment. Possible factors that contributed to perforation were left inguinal hernia containing colon (n = 4), severe diverticulosis (n = 3), and obstructive carcinoma (n = 1). CONCLUSION: Perforation of the colon and rectum is a rare complication of CT colonography. Older age and underlying concomitant colonic disease were present in patients with perforation.

Preauthorization of CT and MRI examinations: assessment of a managed care preauthorization program based on the ACR Appropriateness Criteria and the Royal College of Radiology guidelines.

PURPOSE: To evaluate computed tomography (CT) and magnetic resonance imaging (MRI) utilization patterns before and after the implementation of a preauthorization program based on the ACR Appropriateness Criteria((R)) and the guidelines of the Royal College of Radiologists. MATERIALS AND METHODS: All CT and MRI requests received at the preauthorization center and CT and MRI examinations actually performed were identified by our health care service's centralized computerized database between January 1, 2000, and December 31, 2003. The obligatory preauthorization of CT and MRI requests was established for CT in September 2001 and for MRI in February 2002. All ambulatory CT and MRI examination requests sent for approval during the study period by most of our health care physicians were included in the study. The preauthorization program model is presented, and multiple parameters were evaluated from January 2000 to December 2003, before and after preauthorization was established. RESULTS: Before preauthorization was required, the CT and MRI utilization rates were constantly increasing by 20% and 5% per year for CT and MRI, respectively. After preauthorization was implemented, CT and MRI annual performance rates decreased from 25.9 and 7 examinations per 1,000, respectively, in 2000 to 17.3 and 5.6 examinations per 1,000, respectively, in 2003. The decreases in the utilization of MRI and CT imaging between 2001 and 2003 were 9% (12,129 compared with 11,070 MRI examinations) and 33% (81,223 compared with 57,204 CT examinations), respectively, resulting in substantial, statistically significant cost savings. The deferral rate ranged from 7.5% to 12.2% (mean = 9.8%) for CT and 13.9% to 21.4% (mean = 17%) for MRI. Deferred cases in CT were most commonly in neuroradiology, musculoskeletal radiology, and CT angiography (ranges of deferred cases 9% to 12%, 11% to 12%, and 10% to 12%, respectively). Deferred cases in MRI were most commonly in abdominal and chest radiology (ranges of deferred cases 32% to 37% and 20% to 31%, respectively). Computed tomography was more commonly utilized inappropriately by pediatric professions, and MRI was more commonly utilized inappropriately by medical subspecialty professions. CONCLUSION: Preauthorization of CT and MRI requests results in a substantial decrease in utilization of these modalities with reduction in imaging costs.

Clinical and duplex US assessment of effects of sildenafil on cavernosal arteries of the penis: comparison with intracavernosal injection of vasoactive agents--initial experience.

PURPOSE: To prospectively evaluate the clinical response and hemodynamic changes in cavernosal arteries after oral administration of sildenafil without and with audiovisual sexual stimulation and to compare those responses with responses from intracavernosal injections of vasoactive agents. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. Thirteen consecutive patients (age range, 22-77 years; mean, 60.4 years) with erectile dysfunction were evaluated with clinical assessment and cavernosal duplex ultrasonography (US). The patients were examined at two sessions 3 weeks apart. First, each patient received 100 mg of sildenafil citrate orally and was examined 60 minutes later without any sexual stimulation. Each patient then underwent repeat clinical and duplex US assessment after audiovisual sexual stimulation. Three weeks later, the patients underwent identical clinical evaluation and duplex US after intracavernosal injection of a commercially available combination of papaverine, prostaglandin E1, and phentolamine. Clinical and duplex US data (ie, peak systolic velocity [PSV]) were examined by using the Wilcoxon signed rank test for matched pairs. RESULTS: At rest, the overall mean cavernosal artery PSV was 1.08 cm/sec and remained unchanged after intake of sildenafil without any audiovisual stimulation, with no clinical evidence of erection. With the addition of audiovisual sexual stimulation, eight (62%) of 13 patients had penile congestion or erection, and six (46%) had a PSV greater than 25 cm/sec. With intracavernosal injection of the combination of three drugs, all 13 patients achieved congestion or erection, and 10 (77%) had a PSV greater than 25 cm/sec. Both clinical and duplex US responses to intracavernosal injection were significantly greater than they were to sildenafil with audiovisual sexual stimulation (P = .04 and .003, respectively). CONCLUSION: Oral sildenafil with audiovisual sexual stimulation led to a significant clinical response and increment in blood flow in the cavernosal arteries. However, more patients responded to intracavernosal injection of the combination of three drugs than to sildenafil, and the clinical response was significantly better.