Factors associated with fat stranding on computed tomography in acute appendicitis

Application of Artificial Neural Network Models to Differentiate Between Complicated and Uncomplicated Acute Appendicitis

Preoperative prediction of complicated appendicitis is challenging, and many clinical tools are developed to predict complicated appendicitis. This study evaluated whether a supervised learning method can recognize complicated appendicitis in emergency department (ED). Consecutive patients with acute appendicitis presenting to the ED were enrolled and included into training and testing datasets at a ratio of 70:30. The multilayer perceptron artificial neural network (ANN) models were trained to perform binary outcome classification between uncomplicated and complicated acute appendicitis. Measures of sensitivity, specificity, positive and negative likelihood ratio (LR + and LR-), and a c statistic of a receiver of operating characteristic curve were used to evaluate an ANN model. The simplest ANN model by Bröker et al. including the C-reactive protein (CRP) and symptom duration as variables achieved a c statistic value of 0.894. The ANN models developed by Avanesov et al. including symptom duration, appendiceal diameter, periappendiceal fluid, extraluminal air, and abscess as variables attained a high diagnostic performance (a c statistic value of 0.949) and good efficiency (sensitivity of 78.6%, specificity of 94.5%, LR + of 14.29, LR- of 0.23 in the testing dataset); and our own model by H.A. Lin et al. including the CRP level, neutrophil-to-lymphocyte ratio, fat-stranding sign, appendicolith, and ascites exhibited high accuracy (c statistic of 0.950) and outstanding efficiency (sensitivity of 85.7%, specificity of 91.7%, LR + of 10.36, LR- of 0.16 in the testing dataset). The ANN models developed by Avanesov et al. and H.A. Lin et al. developed model exhibited a high diagnostic performance.

Periappendiceal fat-stranding models for discriminating between complicated and uncomplicated acute appendicitis: a diagnostic and validation study

BACKGROUND

Recent studies have reported promising outcomes of non-operative treatment for uncomplicated appendicitis; however, the preoperative prediction of complicated appendicitis is challenging. We developed models by incorporating fat stranding (FS), which is commonly observed in perforated appendicitis.

MATERIAL AND METHODS

We reviewed the data of 402 consecutive patients with confirmed acute appendicitis from our prospective registry. Multivariate logistic regression was performed to select clinical and radiographic factors predicting complicated acute appendicitis in our model 1 (involving backward elimination) and model 2 (involving stepwise selection). We compared c statistics among scoring systems developed by Bröker et al. (in J Surg Res 176(1):79-83. https://doi.org/10.1016/j.jss.2011.09.049 , 2012), Imaoka et al. (in World J Emerg Surg 11(1):1-5, 2016), Khan et al. (in Cureus. https://doi.org/1010.7759/cureus.4765 , 2019), Kim et al. (in Ann Coloproctol 31(5):192, 2015), Kang et al. (in Medicine 98(23): e15768, 2019), Atema et al. (in Br J Surg 102(8):979-990. https://doi.org/10.1002/bjs.9835 , 2015), Avanesov et al. (in Eur Radiol 28(9):3601-3610, 2018), and Kim et al. (in Abdom Radiol 46:1-12, 2020). Finally, we examined our models by performing the integrated discrimination improvement (IDI) test.

RESULTS

Among enrolled patients, 64 (15.9%) had complicated acute appendicitis. We developed new 10-point scoring models by including the following variables: C-reactive protein, neutrophil to lymphocyte ratio, and computed tomography features of FS, ascites, and appendicolith. A cutoff score of ≥ 6 exhibited a high sensitivity of 82.8% and a specificity of 82.8% for model 1 and 81.3% and 82.3% for model 2, respectively, with c statistics of 0.878 (model 1) and 0.879 (model 2). Compared with the model developed by Bröker et al. which included C-reactive protein and the abdominal pain duration (c statistic: 0.778), the models developed by Atema et al. (c statistic: 0.826, IDI: 5.92%, P = 0.0248), H.Y Kim et al. (c statistics: 0.838, IDI: 13.82%, P = 0.0248), and our two models (IDI: 18.29%, P < 0.0001) demonstrated a significantly higher diagnostic accuracy.

CONCLUSION

Our models and the scoring systems developed by Atema et al. and Kim et al. were validated to have a high diagnostic accuracy; moreover, our models included the lowest number of variables.

Phlegmonous Appearance in the Ipsilateral Paracardiac Fat without Paracardiac Lymph Node Enlargement on Chest CT Favors the Diagnosis of Pleural Tuberculosis over Malignant Pleural Effusion

This study investigated the potential role of paracardiac fat stranding (FS) interspersed with multiple fluid collections (FC) as a clue to differentiate between pleural tuberculosis (pleural TB) and malignant pleural effusion (MPE). The authors retrospectively analyzed chest computed tomography (CT) findings of 428 patients, 351 with pleural TB and 77 with MPE, focusing on the paracardiac fat, and level of pleural adenosine deaminase (ADA) and blood C-reactive protein (CRP). Two radiologists independently evaluated the chest CT findings regarding the paracardiac fat pad ipsilateral to the effusion, including FS, FC, phlegmonous appearance (a combination of the FS and multiple FC), and the presence of lymph node enlargement (>1 cm in short axis diameter). There were significant differences between patients with pleural TB and those with MPE with respect to the prevalence of phlegmonous appearance in the ipsilateral paracardiac fat (47.6% and 10.4%, p < 0.001, OR = 7.8; 95% CI 3.7–16.8) and paracardiac lymph node enlargement (1.4% and 19.5%, p < 0.001, OR = 0.06; 95% CI 0.02–0.2) on CT. In contrast, there was no difference in the prevalence of isolated FS or multiple FC within the ipsilateral paracardiac fat between the two groups. Median pleural ADA and serum CRP level were higher in patients with pleural TB accompanied by phlegmonous appearance in paracardiac fat compared to those without that appearance (ADA: median 104 IU/L versus 90 IU/L, p < 0.001; CRP: 6.5 mg/dL versus 4.2 mg/dL, p < 0.001). In conclusion, phlegmonous appearance in the ipsilateral paracardiac fat without paracardiac lymph node enlargement on chest CT favors a diagnosis of pleural TB over MPE.