Influence of observer experience and training on proficiency in coronary CT angiography interpretation

Purpose

To assess the influence of experience and training on the proficiency in coronary CT angiography (CCTA) interpretation of practitioners with different levels of experience.

Methods and materials

Nine radiologist and cardiologist observers with varying prior CCTA experience ranging from novice to expert independently analyzed two case series of 50 catheter-correlated CCTA studies for coronary artery stenosis (0%, ≤49%, 50–74%, 75–99%, or 100%). Results of the first case series were unblinded and presented along with catheter angiography results to each reader before proceeding to the second series. Diagnostic accuracy on a per-segment basis was compared for all readers and both case series, respectively.

Results

Correlation coefficients between CCTA and catheter angiography initially ranged between good (r = 0.87) and poor (r = 0.26), depending on reader experience, and significantly (p < 0.05) improved in the second case series (range: r = 0.42 to r = 0.91). Diagnostic accuracy was significantly (p < 0.05) higher for more experienced readers (range: 96.5–97.8%) as compared to less experienced observers (range: 90.7–93.6%). After completion of the second case series for less experienced readers sensitivity and PPV significantly (p < 0.05) improved (range: 62.7–67.8%/51.4–84.1%), but still remained significantly (p < 0.05) lower as compared to more experienced observers (range: 89.8–93.3%/80.6–93.3%).

Conclusion

The level of experience appears to be a strong determinant of proficiency in CCTA interpretation. Limited one-time training improves proficiency in novice readers, but not to clinically satisfactory levels.     

Improved diffusion imaging through SNR‐enhancing joint reconstruction

Quantitative diffusion imaging is a powerful technique for the characterization of complex tissue microarchitecture. However, long acquisition times and limited signal‐to‐noise ratio represent significant hurdles for many in vivo applications. This article presents a new approach to reduce noise while largely maintaining resolution in diffusion weighted images, using a statistical reconstruction method that takes advantage of the high level of structural correlation observed in typical datasets. Compared to existing denoising methods, the proposed method performs reconstruction directly from the measured complex k‐space data, allowing for Gaussian noise modeling and theoretical characterizations of the resolution and signal‐to‐noise ratio of the reconstructed images. In addition, the proposed method is compatible with many different models of the diffusion signal (e.g., diffusion tensor modeling and q‐space modeling). The joint reconstruction method can provide significant improvements in signal‐to‐noise ratio relative to conventional reconstruction techniques, with a relatively minor corresponding loss in image resolution. Results are shown in the context of diffusion spectrum imaging tractography and diffusion tensor imaging, illustrating the potential of this signal‐to‐noise ratio‐enhancing joint reconstruction approach for a range of different diffusion imaging experiments. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

Epidemiology of surgically treated gastric cancer in the United States, 1988-2000

The incidence of gastric cancer and the need for subsequent surgery has been decreasing in the United States. However, very few population-based studies on the magnitude of these changes are available. The objective of the present study was to characterize temporal trends in the use of gastric resection in the treatment of gastric cancer. Patients with a primary diagnosis code for gastric cancer (N = 105,887) and a procedure code for gastric resection (N = 23,690) in the Nationwide Inpatient Sample for 1988–2000 were included. The Nationwide Inpatient Sample represents a 20% stratified random sample representative of all United States hospitals. Outcome variables included the overall incidence, in-hospital mortality rate, and length of stay. Rates of surgery are shown as the number of cases per 100,000 hospital discharges. Hospital volume was defined as follows: low volume (1 to 4 cases per year), medium volume (5 to 8 cases per year), and high volume (9 or more cases per year). Rates of gastric resection have shown a 20% decline from 30 cases per 100,000 (1988-1989) to 24 cases per 100,000 (1999-2000) (P = 0.001). In-hospital mortality has not changed over the 13-year period and remains at 7.4%. There was significant variation in mortality across hospitals, with very low-volume centers having an 8.9% mortality rate, whereas very high-volume centers had a 6.4% mortality rate (P < 0.001). The market share of gastric resections performed at high-volume centers increased a small amount from 43% (1988–1989) to 48% (1999-2000) (P = 0.023). Over the 13-year period, length of stay decreased from 15 days (interquartile range [IQR] 11–23) in 1988 to 11 days (interquartile range [IQR] 8–16) in 2000 (P < 0.001). Rates of gastric resection for cancer have shown a modest decline over the past 13 years in the United States. Although the length of stay for these patients has decreased, no significant changes to in-hospital mortality have occurred. Given the declining rates of gastric cancer surgery, and the superior outcomes at high-volume centers, regionalization of care may improve mortality rates for this high-risk surgical procedure. Presented at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 18-22, 2003 (poster presentation).     

A comparison of keratinocyte cell sprays with and without fibrin glue

Fibrin glue is an excellent template for cellular migration and has been shown to be an effective delivery system for cultured autologous keratinocytes. We have investigated whether fibrin glue has any benefit on the percentage of epithelial cover when cultured autologous keratinocytes are sprayed onto a freshly debrided wound bed.Three pigs were used for this study. This provided a total of 18 full thickness, vertically orientated wounds, each 4cm in diameter and isolated in PTFE chambers to prevent re-epithelialisation from the wound margins. Eight wounds were sprayed with cultured autologous keratinocytes suspended in 2ml culture medium and eight wounds were sprayed with cultured autologous keratinocytes suspended in 1ml of the fibrin/aprotinin component of Tisseel fibrin glue (Baxter) mixed with 1ml of culture medium. In the latter group the thrombin component of the fibrin glue kit was applied to the wound bed immediately prior to grafting. The remaining two wounds were used as controls and sprayed with either culture medium or fibrin glue without cells. Epithelial cover was calculated in whole-wound biopsies at 3 weeks using image analysis, histology and immunohistochemistry.The cell suspension in fibrin glue appeared to spread more evenly over the wound surface, with no pooling in the inferior aspect of the wound. However, mean epithelial area at 3 weeks in the fibrin group was 1.6cm(2) per wound compared with 1.8cm(2) for the non-fibrin group, as measured by image analysis of digital photographs. There was no statistically significant difference between the two groups (P=0.802). This surprising result was confirmed by histological analysis of the wound biopsies, with a good correlation between histological and image analysis data (R=0.967). There was no observable difference in the quality of the epithelium on histological and immunohistological analysis of either group.     

Small bowel transit and gastric emptying after biliodigestive anastomosis using the uncut jejunal loop

BACKGROUND: The Roux-en-Y loop is an effective procedure for biliodigestive drainage. However, up to 15% of patients suffer from postoperative cholangitis or blind loop syndrome. A new technique to prevent motility abnormalities has been developed. METHODS: Male Lewis rats were used to compare gastric emptying and transit in the small bowel after either a standard Roux-en-Y anastomosis or a new biliodigestive anastomosis technique which involves creating an "uncut" jejunal loop with luminal occlusion. Unoperated rats served as controls. (99)Technetium HIDA and (111)Indium-tagged amberlite were respectively used to investigate small bowel transit and gastric emptying. RESULTS: Histopathology showed distinctive abnormalities only in the liver of conventional Roux-en-Y animals. No recanalization of the obliterated gut lumen occurred in uncut Roux animals. Distribution of (99)Tc-HIDA and (111)In showed were similar in both groups. Gastric emptying is slowed in both groups. CONCLUSIONS: The uncut proximal jejunum loop is a good alternative to the conventional Roux-en-Y loop and showed preserved small bowel motility and adequate jejunal transit. Gastric emptying is slowed in both groups.     

Surgeon specialty and provider volumes are related to outcome of intact abdominal aortic aneurysm repair in the United States

OBJECTIVE: This study was undertaken to determine the relative importance of surgeon specialty, hospital volume, and surgeon volume on outcome after abdominal aortic aneurysm (AAA) repair. METHODS: Data were reviewed for 3912 patients undergoing AAA repair in the Nationwide Inpatient Sample during 1997. In-hospital mortality was compared between high-volume hospitals and low-volume hospitals and between high-volume surgeons and low-volume surgeons. High-volume hospitals performed more than 35 AAA repairs per year, and high-volume surgeons performed more than 10 AAA repairs per year. Vascular, cardiac, and general surgery specialization was identified by analysis of other procedures performed by each surgeon. RESULTS: Overall, AAA repair mortality was 4.2%, and was lower at high-volume hospitals (3.0%) than at low-volume hospitals (5.5%) (P <.001). Lowest mortality was associated with operations performed by vascular surgeons (2.2%) compared with cardiac surgeons (4.0%) and general surgeons (5.5%) (P <.001). Mortality rates were also lower for high-volume hospitals (2.5%) compared with low-volume hospitals (5.6%) (P <.001). In a risk-adjusted analysis, high-volume hospital, vascular surgery specialty, and high-volume surgeon were all independently associated with lower risk of in-hospital mortality. In this analysis, risk reduction was 30% for high-volume hospitals (95% confidence interval [CI], 2%-51%; P <.05) and 40% for surgery by a high-volume surgeon (95% CI, 12%-60%; P =.01). AAA repair by general surgeons compared with vascular surgeons was associated with 76% greater risk for death (95% CI, 10%-190%; P =.02). No significant difference in mortality was found between cardiac and vascular surgeons. CONCLUSIONS: High surgeon volume and hospital volume of AAA repair were both associated with lower mortality compared with low-volume providers. Increased specialization in vascular surgery was associated with markedly decreased mortality independent of AAA repair volume. Health policy in support of selective referral for AAA repair should consider surgical specialization in addition to provider volume thresholds.     

Nonfatal cerebral air embolism after dental surgery

After removal of four impacted third molars under general anesthesia, our patient developed subcutaneous emphysema, pneumothorax, pneumopericardium, and pneumomediastinum. Soon thereafter, coma with generalized epileptic status ensued. A cerebral magnetic resonance and single photon emission computed tomography showed hypoperfusion of the right thalamus and parietal, temporal, and frontal cortices. The likely mechanism was injection of air by the high-speed dental drill through the soft tissue adjacent to the roots of the lower molars. We were unable to find any previous report of systemic air embolism after oral surgery.     

Surgical treatment of hemangiomas of soft tissue

Hemangioma is one of the most common soft tissue tumors comprising 7% of all benign tumors. The etiology is unclear. Many treatment modalities for the symptomatic deep subdermal or intramuscular hemangioma have been used, but surgical excision is the preferred treatment. During the past 20 years, 89 patients with soft tissue hemangiomas were treated by surgical excision at the authors' institution. This study was done to define the clinical characteristics of pathologically proven hemangiomas and to evaluate the outcome of the operative procedures. Intralesional or marginal excision for symptomatic hemangiomas yields satisfactory results for pain relief, functional recovery, and avoidance of recurrence. According to the data a hemangioma of the soft tissues is a benign lesion in which more aggressive surgery (wide or radical excision) or other modalities such as radiation usually are not warranted.     

Surgical site infections and supplemental perioperative oxygen in colorectal surgery patients: a systematic review

BACKGROUND: Four randomized trials have evaluated the impact of supplemental perioperative oxygen on the incidence of surgical site infections (SSIs), with mixed results. The objectives of this meta-analysis were: (1) To evaluate further the effect of supplemental perioperative oxygen on SSIs after colorectal surgery; and (2) to generate a strategy for future studies to determine definitively the value of this intervention. METHODS: We conducted a MEDLINE search to identify randomized trials of supplemental perioperative oxygen with a primary endpoint of SSI. Fixed-effects and random-effects models were employed, and the null association was tested for each. Tests also were performed for heterogeneity and publication bias. RESULTS: Four studies were identified that satisfied the search criteria. The total number of patients was 943, of whom 477 received supplemental oxygen and 466 served as controls. The pooled risk ratio (RR) for SSI favored the patients who received supplemental oxygen (RR = 0.68; 95% confidence interval [CI] 0.49, 0.94), but this difference was not maintained with a random-effects model (RR = 0.73; 95% CI 0.42, 1.28; p = 0.27). Heterogeneity was present among the studies. There was no evidence of publication bias. CONCLUSIONS: Supplemental perioperative oxygen is associated with a lower risk of SSI in patients undergoing colorectal surgery. The heterogeneity among the individual reports may be secondary to differences in study protocols.