Effects of Expert-Determined Reference Standards in Evaluating the Diagnostic Performance of a Deep Learning Model: A Malignant Lung Nodule Detection Task on Chest Radiographs

Objective@#Little is known about the effects of using different expert-determined reference standards when evaluating the performance of deep learning-based automatic detection (DLAD) models and their added value to radiologists. We assessed the concordance of expert-determined standards with a clinical gold standard (herein, pathological confirmation) and the effects of different expert-determined reference standards on the estimates of radiologists’ diagnostic performance to detect malignant pulmonary nodules on chest radiographs with and without the assistance of a DLAD model. @*Materials and Methods@#This study included chest radiographs from 50 patients with pathologically proven lung cancer and 50 controls. Five expert-determined standards were constructed using the interpretations of 10 experts: individual judgment by the most experienced expert, majority vote, consensus judgments of two and three experts, and a latent class analysis (LCA) model. In separate reader tests, additional 10 radiologists independently interpreted the radiographs and then assisted with the DLAD model. Their diagnostic performance was estimated using the clinical gold standard and various expertdetermined standards as the reference standard, and the results were compared using the t test with Bonferroni correction. @*Results@#The LCA model (sensitivity, 72.6%; specificity, 100%) was most similar to the clinical gold standard. When expertdetermined standards were used, the sensitivities of radiologists and DLAD model alone were overestimated, and their specificities were underestimated (all p-values < 0.05). DLAD assistance diminished the overestimation of sensitivity but exaggerated the underestimation of specificity (all p-values < 0.001). The DLAD model improved sensitivity and specificity to a greater extent when using the clinical gold standard than when using the expert-determined standards (all p-values < 0.001), except for sensitivity with the LCA model (p = 0.094). @*Conclusion@#The LCA model was most similar to the clinical gold standard for malignant pulmonary nodule detection on chest radiographs. Expert-determined standards caused bias in measuring the diagnostic performance of the artificial intelligence model.

Neck circumference correlates with tumor size and lateral lymph node metastasis in men with small papillary thyroid carcinoma

BACKGROUND/AIMS: Obesity is correlated with numerous diseases, including thyroid cancer, but the clinical significance of obesity with regard to the clinical characteristics of thyroid cancer remains unclear. Neck circumference is an index of upper-body adipose tissue distribution. METHODS: In total, 401 patients with papillary thyroid carcinoma (PTC) measuring < or = 2 cm were included. Neck circumference was measured horizontally at the level just below the thyroid cartilage on preoperative neck computed tomographic images. RESULTS: Neck circumference correlated significantly with tumor size in men (p = 0.001) but not in women (p = 0.930). Body mass index (BMI) did not significantly correlate with tumor size in either sex. Neck circumference was significantly larger in men with lateral lymph node (LN) metastasis than in those without (p = 0.004). Neck circumference and BMI did not differ significantly in women according to other factors such as tumor size, multifocality, extrathyroid extension, and LN metastasis. Tumor size and the prevalence of lateral LN metastasis in men tended to increase in the middle/large neck circumference subgroup compared with those in the low neck circumference subgroup. Multivariate logistic regression analysis revealed that neck circumference (p = 0.009) was a predictor for the presence of lateral LN metastasis in men. BMI was not a predictive factor for lateral LN involvement in either sex. CONCLUSIONS: Neck circumference, an indicator of central or visceral obesity but not BMI, may be associated with some prognostic factors in men with small PTC.

Predictive Factors for Incidental Contralateral Carcinoma in Patients with Unilateral Micropapillary Thyroid Carcinoma

BACKGROUND: Whether thyroid lobectomy alone is a sufficient treatment for papillary thyroid microcarcinoma (PTMC) remains controversial. The aim of this study is to evaluate the predictive factors for incidental contralateral carcinoma in patients confirmed of unilateral PTMC preoperatively. METHODS: Between January 2007 and December 2009, 393 patients underwent thyroid surgery for unifocal and unilateral PTMC preoperatively at Pusan National University Hospital. A total thyroidectomy with central neck dissection was routinely performed for these patients during this study period. RESULTS: Among the 393 cases in the cohort, 77 patients (19.6%) had incidental PTMC in the contralateral lobe. In patients with incidental contralateral carcinoma, there was higher prevalence in extrathyroid extension, occult ipsilateral carcinoma, pathologic Hashimoto's thyroiditis, and central lymph node metastasis compared to those without contralateral carcinoma. The mean tumor size also increased in patients with contralateral carcinoma. Multivariate logistic regression showed that extrathyroid extension (P = 0.049), occult ipsilateral carcinoma (P < 0.001), pathologic Hashimoto's thyroiditis (P = 0.038), and central lymph node metastasis (P = 0.002) were predictive factors for incidental contralateral carcinoma. CONCLUSION: In conclusion, multifocality in the ipsilateral lobe, central lymph node metastasis, extrathyroid extension, and Hashimoto's thyroiditis is associated with the presence of contralateral carcinoma. Thus, if these factors are found by preoperative and/or postoperative evaluation, total thyroidectomy or completion thyroidectomy is necessary for the treatment of PTMC.

Cystatin C as an Early Biomarker of Nephropathy in Patients with Type 2 Diabetes

This study was done to evaluate clinical usefulness of cystatin C levels of serum and urine in predicting renal impairment in normoalbuminuric patients with type 2 diabetes and to evaluate the association between albuminuria and serum/urine cystatin C. Type 2 diabetic patients (n = 332) with normoalbuminuria (n = 210), microalbuminuria (n = 83) and macroalbuminuria (n = 42) were enrolled. Creatinine, urinary albumin levels, serum/urine cystatin C and estimated glomerular filtration rate (eGFR by MDRD [Modification of Diet in Renal Disease] and CKD-EPI [Chronic Kidney Disease Epidemiology Collaboration] equations) were determined. The cystatin C levels of serum and urine increased with increasing degree of albuminuria, reaching higher levels in macroalbuminuric patients (P < 0.001). In multiple regression analysis, serum cystatin C was affected by C-reactive protein (CRP), sex, albumin-creatinine ratio (ACR) and eGFR. Urine cystatin C was affected by triglyceride, age, eGFR and ACR. In multivariate logistic analysis, cystatin C levels of serum and urine were identified as independent factors associated with eGFR < 60 mL/min/1.73 m2 estimated by MDRD equation in patients with normoalbuminuria. On the other hand, eGFR < 60 mL/min/1.73 m2 estimated by CKD-EPI equation was independently associated with low level of high-density lipoprotein in normoalbuminuric patients. The cystatin C levels of serum and urine could be useful markers for renal dysfunction in type 2 diabetic patients with normoalbuminuria.

A case of acute renal failure caused by extrinsic compression of the left renal artery in lymphoma / 대한내과학회지

Malignant lymphomas can involve any organ, but rarely cause acute renal failure as an initial manifestation. Impaired renal function secondary to renal arterial compression by a tumor mass has not been reported. A 50-year-old man was admitted with low back pain, weight loss, and a palpable abdominal mass. He developed non-oliguric acute renal failure secondary to extrinsic compression of the left renal artery by enlarged lymph nodes in the posterior wall of the pelvic cavity. Abdominal computed tomography (CT) showed the complete absence of perfusion of the left kidney due to extrinsic compression of the left renal artery by a huge diffuse large B cell lymphoma (stage IVa, International Prognostic Index score 3). We report a case of malignant lymphoma presenting as acute renal failure due to extrinsic compression of the left renal artery; this was treated successfully with systemic combination chemotherapy

Aortic Elasticity was not Related with Duration, Bath Ankylosing Spondylitis Disease Activity Index / 대한류마티스학회지

OBJECTIVE: Cardiac manifestations are well recognized complication of ankylosing spondylitis (AS). They include aortic incompetence, conduction defects, mitral valve disease, pericarditis and cardiomyopathy. There was one study to evaluate the change of aortic elasticity in AS patient and the association between the aortic strain and duration of AS, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). We designed this study to determine whether aortic elasticity changes in Korean AS patients and is associated with the duration of AS or BASDAI. METHODS: 18 AS patients without cardiovascular involvement and 18 sex and age- matched healthy subjects were enrolled in the study. Aortic strain and distensibility was calculated from aortic diameters measured by echocardiography and blood pressure measured by sphygmomanometry. RESULTS: The mean aortic strain and mean aortic distensibility in AS group indicated that there was not any correlation with those of control group, based on the statistical analysis. Moreover, there was no statistical correlation between the means of aortic strain, aortic distensibility and the duration or BASDAI of AS. CONCLUSION: In patients with AS without cardiac involvement, the aortic elasticity was not decreased than that of control group, and aortic strain and distensibility were not correlated with the duration or BASDAI of AS.

A Case of a Gastric Gastrointestinal Stromal Tumor with a Fistula and Gastrointestinal Bleeding / 대한소화기내시경학회지

There has been much debate on the origin, differentiation and prognosis of gastrointestinal stromal tumors (GIST). Based on recent studies, we consider Cajal interstitial cell as the origin of a GIST. The common symptoms of a GIST are abdominal pain, hemorrhage, and the presence of a mass. However, there are few reported cases of a GIST with abscess pockets that communicate with the lumen of the stomach via a fistula. We report a case of a GIST of the stomach presenting with an abscess and a fistula communicating with the lumen of the stomach. An 84-year-old man presented with continuous fever and general weakness. We were able to diagnose the disease by an endoscopic examination, CT scan, biopsy and by cellular immunohistochemical staining.

A Case of Multiple Myeloma with Pulmonary Thromboembolism Diagnosed by Transthoracic Echocardiography

Cancer is a major risk factor for pulmonary thromboembolism. Occasionally, the thromboembolic event occurs before the diagnosis of cancer. We report a rare case of massive pulmonary thromboembolism with multiple myeloma diagnosed by transthoracic echocardiography.

Effects of Closure of the Arteriovenous Fistula on Left Ventricular Mass and Function in Kidney Transplantation Patients

BACKGROUND: Cardiovascular disease is the leading cause of morbidity and mortality in kidney transplantion recipients. Enhanced cardiac load by the persistence of functioning AVF in posttransplant period is associated with LV hypertrophy and may adversely influence cardiac outcome. METHODS: To investigate the impact of AVF on LV mass and function in kidney transplant recipients, 46 patients with functioning AVF were randomly assigned to surgical closure of AVF (fistular closing group, FC, n=23) or maintenance of fistula (fistular maintenance group, FM, n=23). Serum creatinine of all participants was stable(1.4+/-0.3). Mean age was 46+/-11. Mean posttransplant month was 78+/-53 (12-161). Echocardiography and determination of N-terminal pro-BNP, cTnT and CRP were done at 0, 1 and 6 months in group 1 (FC), and at 0 and 6 months in group 2 (FM). RESULTS: Baseline echocardiographic indices of systolic and diastolic LV function such as EF, E/A, E/E' and Tei index were not significantly different between groups. In patients whose AVF was surgically closed, LV mass (247.7+/-76.8 to 235.2+/-66.5, p=0.015) and LV mass index (144.0+/-10.1 to 137.1+/-8.6, p=0.02) significantly reduced at one month after closure, and no further significant change was observed at 6 months. In two groups no significant change in LV systolic and diastolic performance indices were observed. BNP, cTnT and CRP did not differ between groups in baseline value and did not change after closure. CONCLUSION: We conclude that the persistence of functioning AVF in kidney transplantation recipients is associated with LVH, and which can be reduced by closure of fistula. As LVH is one of major determinants of cardiovascular outcome in transplant patients as well as in general population, it would be prudent to close the fistula in patients with stable graft function.

Quantitative Assessment of Left Atrial Functional Changes in Patients with Atrial Fibrillation by Tissue Doppler Strain and 2-Dimensional Strain Imaging

BACKGROUND AND OBJECTIVES: Conservation of the normal atrial size and architecture by preventing the structural atrial remodeling that's due to atrial fibrillation (AF) seems to be of prime importance for the management of AF patients. We attempted to assess the relevance of performing strain echocardiography for quantitatively assessing the left atrial (LA) status in AF patients. SUBJECTS AND METHODS: Tissue Doppler strain and 2-dimensional strain imaging were performed in 15 patients with chronic AF, in 15 patients with paroxysmal AF and in 15 healthy age-matched controls with using a GE vivid 7 dimension apparatus. The LA diameter, LA volume index and mitral inflow parameters were measured by standard echocardiography. Longitudinal peak strain and the strain rate were obtained from 2 different areas of the basal left atrial free wall and also the inter-atrial septum in the apical 4 chamber view with using the tissue Doppler strain. The mean peak systolic rate (Sm-SR), the peak early diastolic rate (Em-SR) and the peak late diastolic strain rate (Am-SR) were measured at the inter-atrial septum in the apical 4 chamber view with using the 2-dimensional strain imaging. RESULTS: The peak strain/rate, the Sm-SR and the Em-SR were significantly reduced in the AF group as compared with the normal controls, and they were especially reduced in the chronic AF group. There were no significant differences for the LA size and A wave velocity between the paroxysmal AF group and the normal group; however, the peak systolic strain/rate, the Em-SR and the Am-SR were significantly lower in the paroxysmal AF group than in the normal controls. CONCLUSION: The lower values of atrial Sm-SR, Em-SR and Am-SR revealed that active contraction and passive stretching of the LA wall may be impaired in some patients suffering with paroxysmal AF even before LA enlargement occurs, and this is possibly because of reduced atrial compliance. Our results indicated that strain echocardiography enabled quantitatively precise assessment of the LA contractile function and it can provide clinically useful information concerning the early reversible atrial functional changes in patients suffering with AF, and especially in the paroxysmal AF patients.