Deep learning image reconstruction algorithm for abdominal multidetector CT at different tube voltages: assessment of image quality and radiation dose in a phantom study.

OBJECTIVES: To compare the image quality and radiation dose of a deep learning image reconstruction (DLIR) algorithm compared with iterative reconstruction (IR) and filtered back projection (FBP) at different tube voltages and tube currents. MATERIALS AND METHODS: A customized body phantom was scanned at different tube voltages (120, 100, and 80 kVp) with different tube currents (200, 100, and 60 mA). The CT datasets were reconstructed with FBP, hybrid IR (30% and 50%), and DLIR (low, medium, and high levels). The reference image was set as an image taken with FBP at 120 kVp/200 mA. The image noise, contrast-to-noise ratio (CNR), sharpness, artifacts, and overall image quality were assessed in each scan both qualitatively and quantitatively. The radiation dose was also evaluated with the volume CT dose index (CTDIvol) for each dose scan. RESULTS: In qualitative and quantitative analyses, compared with reference images, low-dose CT with DLIR significantly reduced the noise and artifacts and improved the overall image quality, even with decreased sharpness (p < 0.05). Despite the reduction of image sharpness, low-dose CT with DLIR could maintain the image quality comparable to routine-dose CT with FBP, especially when using the medium strength level. CONCLUSION: The new DLIR algorithm reduced noise and artifacts and improved overall image quality, compared to FBP and hybrid IR. Despite reduced image sharpness in CT images of DLIR algorithms, low-dose CT with DLIR seems to have an overall greater potential for dose optimization. KEY POINTS: • Using deep learning image reconstruction (DLIR) algorithms, image quality was maintained even with a radiation dose reduced by approximately 70%. • DLIR algorithms yielded lower image noise, higher contrast-to-noise ratios, and higher overall image quality than FBP and hybrid IR, both subjectively and objectively. • DLIR algorithms can provide a better image quality, much better than FBP and even better than hybrid IR, while facilitating a reduction in radiation dose.

The potential for reduced radiation dose from deep learning-based CT image reconstruction: A comparison with filtered back projection and hybrid iterative reconstruction using a phantom.

ABSTRACT: The purpose of this phantom study is to compare radiation dose and image quality of abdominal computed tomography (CT) scanned with different tube voltages and tube currents, reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (IR) and deep learning image reconstruction (DLIR) algorithms.A total of 15 CT scans of whole body phantoms were taken with 3 different tube voltages and 5 different tube currents. The images were reconstructed with FBP, 30% and 50% hybrid IR adaptive statistical iterative reconstruction (ASIR-V), and low, medium and high strength DLIR algorithms. The image scanned with tube voltage/tube current of 120 kV/ 200 mA and reconstructed with FBP algorithm was chosen as the reference image. Five radiologists independently analyzed the images individually and also compared it with the reference image in overall, using the visual grading analysis. The mean score of each image was calculated and compared.Using DLIR algorithms, the radiation dose was reduced by 65.5% to 68.1% compared with the dose used in the reference image, while maintaining comparable image quality. Using the DLIR algorithm of medium strength, the image quality was even better than the reference image with a reduced radiation dose up to 36.2% to 50.0%. The DLIR algorithms generated better quality images than ASIR-V algorithms in all the data sets. In addition, among the data sets reconstructed with DLIR algorithms, image quality was the best at the medium strength level, followed by low and high.This phantom study suggests that DLIR algorithms may be considered as a new reconstruction technique by reducing radiation dose while maintaining the image quality of abdominal CTs.

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Perineal involvement by metastatic renal cell carcinoma (RCC) is very rare, and there are only few reports on its radiological findings in the literature. Here, we present a case of a 76-year old female who presented with perineal pain caused by metastatic clear cell RCC. We discuss the radiological changes of the tumor before and after targeted therapy.

Ascaris-mimicking common bile duct stone: A case report.

BACKGROUND: In most cases, it is not difficult to differentiate common bile duct (CBD) stone from Ascaris infection because they are different disease entities and have different imaging findings. The two diseases usually demonstrate unique characteristic findings on computed tomography or magnetic resonance cholangiopancreatography. However, we report a rare case from our experience in which a CBD stone mimicked and was misdiagnosed as Ascaris. CASE SUMMARY: A 72-year-old male presented with elevated serum liver enzymes. Computed tomography showed a hyper-attenuated, elongated lesion in the CBD lumen and associated biliary inflammation. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography revealed a linear filling defect in the bile duct. Moreover, elongated echogenic material with a central hypoechogenic area was seen on endoscopic ultrasound. Although the imaging findings caused us to suspect infection with the nematode Ascaris, the lesion was revealed to be a dark-brown-colored CBD stone through endoscopic extraction. CONCLUSION: We report a rare case of a CBD stone that mimicked Ascaris. We also review the literature for side-by-side comparisons of the imaging features of CBD stones and ascariasis.

Determining Malignant Potential of Intraductal Papillary Mucinous Neoplasm of the Pancreas: CT versus MRI by Using Revised 2017 International Consensus Guidelines.

Background Several changes have been made to the revised 2017 international consensus guidelines for management of pancreatic intraductal papillary mucinous neoplasms (IPMNs). However, the diagnostic performance is yet to be verified. Purpose To evaluate the revised guidelines for predicting malignant potential of pancreatic IPMNs and to compare diagnostic performance and intermodality agreement between contrast material-enhanced CT and MRI. Materials and Methods In this retrospective study, two radiologists analyzed the preoperative contrast-enhanced CT and MRI of patients with surgically resected pancreatic IPMNs from January 2007 to December 2017. The diagnostic performance of CT and MRI were analyzed by using receiver operating curve analysis. Intermodality agreement was assessed by using weighted κ and intraclass correlation coefficient values. Results A total of 86 patients (mean age, 67.6 years ± 8.9 [standard deviation]; 47 men and 39 women) with pancreatic IPMNs (benign, 58; malignant, 28) were included. At both CT and MRI, enhancing mural nodule (P < .001), abrupt main pancreatic duct caliber change (P < .001), lymphadenopathy (P = .006), larger main pancreatic duct size (P = .003), and faster cyst growth rate (P = .04) were more common in malignant than benign IPMNs. Irrespective of the modality, enhancing mural nodule of 5 mm or greater had the highest odds ratio (25 at CT vs 29 at MRI). The diagnostic performance of CT (area under the receiver operating characteristic curve, 0.83 [95% confidence interval: 0.75, 0.92]) and MRI (area under the receiver operating characteristic curve, 0.86 [95% confidence interval: 0.77, 0.95]) for predicting malignant IPMNs were comparable (P = .43), with good intermodality agreement (κ = 0.70). Conclusion Among revised features, enhancing mural nodule of 5 mm or greater had the strongest association with malignant intraductal papillary mucinous neoplasm (IPMN), and diagnostic performance for prediction of malignant IPMNs were comparable between contrast-enhanced CT and MRI with good intermodality agreement. © RSNA, 2019 Online supplemental material is available for this article.

Peritoneal sarcoidosis: A case report.

RATIONALE: Sarcoidosis is an idiopathic granulomatous disease. Although the lungs are most commonly involved, any organ may be affected. To assist with future diagnoses, we describe a rare case of peritoneal sarcoidosis in a young female patient, and present a literature review. PATIENT CONCERNS: A 32-year-old female patient presented to our institution with abdominal discomfort. She was evaluated with contrast-enhanced abdominal computed tomography (CT), and multiple enlarged lymph nodes were detected at the hepatic artery and left gastric artery nodal stations. The patient was lost during follow-up, but returned after 7 months and again underwent abdominal CT. This revealed diffuse nodular thickening of the peritoneum and the appearance of omental cake in her abdomen. DIAGNOSIS: Excisional biopsy of a lymph node was performed and extrapulmonary sarcoidosis was confirmed. INTERVENTIONS: The patient was treated with corticosteroid. OUTCOMES: A follow-up abdominal CT scan after two weeks revealed decreases in the numbers and sizes of the previously enlarged lymph nodes, and improvement in the ascites and peritoneal thickening. LESSIONS: Peritoneal sarcoidosis should be considered as an additional differential diagnosis when peritoneal carcinomatosis or tuberculous peritonitis are suspected. In this regard, serum levels of angiotensin-converting enzyme (ACE) may be a valuable diagnostic indicator of unusual sarcoidosis presentations.

Magnetic resonance imaging features predictive of an incomplete response to transarterial chemoembolization in patients with hepatocellular carcinoma: A STROBE-compliant study.

To identify pretreatment magnetic resonance imaging (MRI) features associated with an incomplete response (IR) to transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC).The medical records of 89 patients with HCC who had undergone a first TACE were reviewed retrospectively. The size, visual attenuation in the arterial phase, signal intensity (SI) on T1-, T2-, and diffusion-weighted images, and apparent diffusion coefficient (ADC) values of each lesion were evaluated on pretreatment images. The response to TACE was routinely assessed at 4 weeks post-treatment by 4-phase computed tomography. The HCC patients were classified as complete or incomplete responders based on the arterial-phase enhancement of the target lesion.In multivariate analysis, larger lesion diameter (P = .004, OR = 1.06 per millimeter, 95% CI = 1.02-1.11), faint enhancement on arterial phase (P = .021, OR = 3.24, 95% CI = 1.22-9.14), and non-low SI on T1-weighted images (P = .016, OR = 3.36, 95% CI = 1.29-9.32) were significantly associated with increased odds of an IR to TACE in HCC patients.An iso-to-high T1-weighted SI by pretreatment MRI was an independent predictor of an incomplete response to TACE in patients with HCC, in addition to faint arterial enhancement and lesion size.

Differentiation of hepatic abscess from metastasis on contrast-enhanced dynamic computed tomography in patients with a history of extrahepatic malignancy: emphasis on dynamic change of arterial rim enhancement.

OBJECTIVES: The objective of the study is to identify computed tomography (CT) findings that differentiate hepatic abscess from hepatic metastasis in a patient with a history of extrahepatic malignancy. MATERIALS AND METHODS: This retrospective study included 30 patients with 93 hepatic abscesses and 40 patients with 125 hepatic metastases who had a history of extrahepatic malignancy and underwent contrast-enhanced dynamic CT with arterial phase (AP) and portal venous phase (PVP). The diagnosis of hepatic abscess and hepatic metastasis was made using pathological confirmation or clinical diagnosis. Margin, patchy parenchymal enhancement, arterial rim enhancement, dynamic change of arterial rim enhancement, size discrepancy of lesions between arterial and portal phases, bile duct dilatation, perilesional hyperemia, and perilesional low density were evaluated by two radiologists independently. Significant findings for differentiating two groups were identified at univariate and multivariate analysis with nomogram for predicting hepatic abscess. Interobserver agreement was also analyzed for each variable. RESULTS: Multivariate analysis revealed that patchy parenchymal enhancement (P < 0.001), arterial rim enhancement persistent through PVP (P < 0.001), and perilesional hyperemia (P = 0.013) were independent significant findings to predict hepatic abscess than metastasis. Among them, arterial rim enhancement persistent through PVP showed a highest odds ratio (OR 33.73) on multivariate analysis and a highest predictor point on a nomogram for predicting hepatic abscess. When two of these three criteria were combined, 80.7% (75/93) of hepatic abscess were correctly identified, with a specificity of 85.6% (107/125). When all three criteria were satisfied, specificity was up to 100% (125/125). CONCLUSIONS: At contrast-enhanced dynamic CT, patchy parenchymal enhancement, arterial rim enhancement persistent through PVP, perilesional hyperemia, and their combinations may be reliable CT features for differentiating hepatic abscess from metastasis in patients with a history of primary extrahepatic malignancy.

Computed tomographic features of inflammatory myofibroblastic tumour of the stomach in adult patients: An analysis of five multicentre cases with literature review.

INTRODUCTION: The aim of this study was to describe the clinical and computed tomography (CT) features of gastric inflammatory myofibroblastic tumour (IMT) in adult patients and provide a review of the literature. METHODS: Five adult patients with surgically resected and pathologically confirmed gastric IMT were included in the study from four tertiary referral centres. Clinical history was assessed for determination of patient demographics and symptoms at presentation. All patients underwent contrast-enhanced abdominal CT, and two radiologists assessed the CT features by consensus. Also, abdominal CT findings from previous case reports of nine adult patients with gastric IMT were reviewed and summarised. RESULTS: Of five gastric IMTs, four (80%) appeared as a well-defined subepithelial mass and only one (20%) appeared as an irregular wall thickening. All of five gastric IMTs showed strong enhancement. When we analysed the CT features of nine cases from previously published literatures combined with our five cases, predominant imaging feature of gastric IMT was a well-defined subepithelial mass with strong enhancement. Perigastric infiltration or direct invasion of the neighbouring organs was rarely seen. CONCLUSION: Gastric IMT in adult patients appeared either as a well-defined subepithelial mass or irregular wall thickening, with mostly strong enhancement. Although rare, these imaging feature may be helpful for diagnosis of gastric IMT.

Pericecal herniation of sigmoid colon diagnosed by computed tomography: Two case reports.

INTRODUCTION: Computed tomography (CT) plays an important role in diagnosing specific types of internal hernias and their complications. In particular, pericecal hernia of the sigmoid colon has never been reported in the English literature. CASE PRESENTATION: The first patient was a 46-year-old female presented to our institution due to acute abdominal pain. The second patient was a 55-year-old male presented to our institution with continuous diarrhea. The patient underwent colonoscopy for further evaluation. However, even with sufficient air insufflation and repetitive maneuvers, the colonoscope could not proceed beyond the narrowed level of the sigmoid colon. In both cases, contrast-enhanced abdominal CT was done and a herniated loop of sigmoid colon was noted in the posterolateral aspect of the cecum and ascending colon. Thus, a diagnosis of pericecal herniation of the sigmoid colon was established. CONCLUSION: This case study indicates that radiologic examination can be helpful in detecting pericecal herniation of the sigmoid colon.

Pope's hat sign: another valuable CT finding of early acute cholecystitis.

PURPOSE: To determine the diagnostic performance of minor computed tomography (CT) findings for acute cholecystitis and demonstrate the incremental benefit of pope's hat sign as an additional minor CT finding in patients suspected to have early acute cholecystitis. MATERIALS AND METHODS: Two radiologists reviewed CT scans of 116 patients with early acute cholecystitis and 116 control patients. All cases in the patient group were surgically proven to have acute cholecystitis and preoperative dynamic CT scans. Evaluated CT parameters included major criteria (gallstone, distension of gallbladder (GB) lumen, GB wall edema, pericholecystic fat infiltration, and pericholecystic fluid collection) and minor criteria (GB bed hyperemia, tensile GB fundus sign, hyperdense GB wall sign, increased bile attenuation within GB, and pope's hat sign). RESULTS: In a univariate analysis, among the minor criteria, GB bed hyperemia, tensile GB fundus sign, increased bile attenuation within GB, and pope's hat sign were more frequently observed (P < 0.05) in the early acute cholecystitis group. The optimal cut-off value of GB distension for discriminating between the two groups was 3.05 cm. In a multivariable analysis, GB bed hyperemia, pope's hat sign, and GB lumen > 3.05 cm were significant findings for differentiating the two groups (P < 0.001). Among all combinations of these findings, the combination of GB bed hyperemia and pope's hat sign exhibited the highest specificity (96.5%) and the combination of all three findings showed the highest sensitivity (94.0%). CONCLUSION: Pope's hat sign is a new finding that could improve CT diagnostic performance for early acute cholecystitis in patients with RUQ pain in the emergency department. The combination of pope's hat sign with GB bed hyperemia or GB lumen distension > 3.05 cm may be even more helpful in the early stage or in mild forms of acute cholecystitis.

Accessory gallbladder in an intrahepatic location mimicking a cystic tumor of the liver: A case report.

BACKGROUND: Double gallbladder (GB) is a rare congenital anomaly of the biliary system characterized by the presence of an accessory GB. CLINICAL FINDINGS: A 38-year-old female presented with a history of right upper quadrant (RUQ) pain. Computed tomography (CT) showed a lobulated cystic mass involving the center portion of liver. Magnetic resonance imaging (MRI) additionally revealed a tubular structure of T2 bright signal intensity (SI), which connected the cystic lesion of the liver to the bile duct. Preoperative endoscopic retrograde cholangiopancreatography (ERCP) confirmed the connection between the intrahepatic cystic lesion and the left main hepatic duct. We regarded as a cystic mass with biliary communication, such as a cystic intraductal papillary neoplasm of the bile duct (IPNB) or localized Caroli disease. The patient underwent partial hepatectomy for the cystic mass of the liver and a final diagnosis of chronic inflammation of an intrahepatically located accessory GB was made. CONCLUSION: We report a case of an accessory GB in an intrahepatic location mimicking a cystic mass such as cystic IPNB or localized Caroli disease of the liver showing a cystic mass with biliary communication.

The Effectiveness of Real-Time Feedback with an Audible Pulse: A Preliminary Study in Renal Doppler Ultrasonography.

PURPOSE: The effectiveness of real-time feedback using an audible pulse in renal Doppler ultrasonography was evaluated. METHODS: This study was approved by the institutional review board of our hospital. Written informed consent was provided by all volunteers at enrollment. The 26 healthy volunteers enrolled in this study underwent Doppler ultrasound of both kidneys using audible and inaudible pulses in randomized order and at 1-week intervals. Doppler waveforms were obtained at the interlobar or arcuate arteries using a 2-mm Doppler gate. Each session was considered complete when reproducible waveforms were obtained for 5 s in three predefined regions of the kidney. The scan times needed to obtain waveforms of the right and left kidneys were recorded separately. Measurements were compared using a paired t-test and a two-sample Wilcoxon rank-sum test. RESULTS: The total recorded Doppler sonography scan time for each kidney ranged from 33 to 146 s. The mean scan time was 56.83 s (right, 58.19 s; left, 55.46 s) in the audible session and 72.58 s (right, 72.08 s; left, 73.08 s) in the inaudible session. The scan times were significantly shorter in the audible than inaudible session (p<0.001), whereas the difference in the scan times between the right and left kidneys was not significant. The order of the sessions had no effect on the total scan time. CONCLUSION: Real-time feedback using an audible pulse may encourage patient cooperation during breath-holding and can shorten the time needed to perform Doppler ultrasonography.

Correlation of cystoscopically confirmed periureterally located hunner lesion with vesicoureteral reflux: preliminary study in patients with interstitial cystitis.

OBJECTIVE: The purpose of this study is to evaluate the incidence of vesicoureteral reflux (VUR) in patients with interstitial cystitis (IC) and to explore the correlation between periureterally located Hunner lesions and ipsilateral VUR. MATERIALS AND METHODS: We evaluated 344 patients with IC who underwent cystoscopy (March 2012 to July 2013). Among these patients, 25 underwent voiding cystourethrography (VCUG) to check for the presence of VUR. We reviewed the cystoscopy findings (grade and location of Hunner lesions) and the results of VCUG (presence and grade of VUR). The relationship between VUR and periureterally located Hunner lesions and the association between cystoscopic grading of IC and VUR were evaluated. RESULTS: Of the 25 patients with IC, seven (28%) had VUR (two bilateral and five unilateral). Among nine separate ureters with VUR, seven (78%) had associated periureterally located Hunner lesions, as evaluated cystoscopically. The median bladder capacity was 200 mL for patients with VUR and 230 mL for patients without VUR, with no statistically significant difference between the two groups (p>0.05). There was a strong correlation between the presence of VUR and ipsilateral periureterally located Hunner lesions (p<0.05). However, there was no association between the severity of cystoscopy grading and the presence of VUR (p>0.05). CONCLUSION: According to our study, VUR is not an uncommon complication in patients with IC, and there is a statistically significant correlation between VUR and periureterally located Hunner lesions. We assume that, along with the decrease in bladder capacity, a periureterally located Hunner lesion may be an important factor in the development of VUR.

Henoch-Schonlein purpura: ultrasonography of scrotal and penile involvement.

Testicular or scrotal involvement has been reported in children with Henoch-Schonlein purpura (HSP), but there are very few reports on penile involvement. We report the initial and follow-up ultrasonographic findings of scrotal and penile involvement of HSP in a 5-year-old boy. On ultrasonography, scrotal soft tissue thickening and epididymal swelling with increased vascularity were noted, and on the penis, a focal mass-like lesion appeared on the dorsal surface of the distal penis, having a hypoechoic mass-like appearance without visible vascular flow on a Doppler study. After 2 days of treatment, follow-up ultrasonography showed normal scrotum and penis with a resolved soft tissue mass-like lesion. Therefore, we think that HSP ultrasonographic findings involving the scrotum and penis might help to diagnose scrotal and penile involvement in a case of HSP and to avoid unnecessary medication and/or surgical procedures.

Contrast-induced nephropathy in patients undergoing intravenous contrast-enhanced computed tomography in Korea: a multi-institutional study in 101487 patients.

OBJECTIVE: To evaluate the prevalence of known risk factors for contrast-induced nephropathy (CIN) and their association with the actual occurrence of CIN in patients undergoing intravenous contrast-enhanced computed tomography (CECT) in Korea. MATERIALS AND METHODS: Patients who underwent CECT in 2008 were identified in the electronic medical records of 16 tertiary hospitals of Korea. Data on demographics, comorbidities, prescriptions and laboratory test results of patients were collected following a standard data extraction protocol. The baseline renal function was assessed using the estimated glomerular filtration rate (eGFR). We identified the prevalence of risk factors along the eGFR strata and evaluated their influence on the incidence of CIN, defined as a 0.5 mg/dL or 25% increase in serum creatinine after CECT. RESULTS: Of 432425 CECT examinations in 272136 patients, 140838 examinations in 101487 patients met the eligibility criteria for analysis. The mean age of the participants was 57.9 ± 15.5 years; 25.1% of the patients were older than 70 years. The prevalence of diabetes mellitus was 11.9%, of hypertension 13.7%, of gout 0.55% and of heart failure was 1.7%. Preventive measures were used in 40238 CECT examinations (28.6%). The prevalence of risk factors and use of preventive measures increased as the renal function became worse. A CIN was occurred after 3103 (2.2%) CECT examinations, revealing a significant association with decreased eGFR, diabetes mellitus, and congestive heart failure after adjustment. CONCLUSION: Risk factors for CIN are prevalent among the patients undergoing CECT. Preventive measures were seemingly underutilized and a system is needed to improve preventive care.

Diagnostic effectiveness of dynamic colpocystoproctography in women planning for combined surgery with urinary incontinence and pelvic organ prolapse.

OBJECTIVE: To evaluate the advantage of performing the dynamic cystoproctography (DCP) in patients planning for combined surgery due to urinary incontinence and pelvic organ prolapse (POP). MATERIALS AND METHODS: We performed DCP on a total of 113 consecutive women with POP and compared the findings of the physical examination with POP quantification against those of DCP including squeezing, straining and evacuation phases, and analyzed the changes to the rates of surgical planning. For statistical analysis, sensitivity, specificity, and positive predictive value of each test were performed. RESULTS: DCP identified an additional 10 cases of cystocele, 32 cases of rectocele, 2 cases of enterocele, 4 cases of sigmoidocele, and 8 cases of rectal intussusception compared to those cases who were only included for a physical examination. The initial surgical plan was changed in a total of 24 cases (22.1%). The prevalence of bowel symptoms in the group in which the surgical plan changed was higher than in the group with no changes to the surgical plan (p = 0.023). CONCLUSIONS: DCP may be a more sensitive test for diagnosing POP compared to physical examination alone, and it is useful to patients with bowel symptoms by making surgical planning for combined surgery with stress urinary incontinence and POP.

Sonography of intrascrotal appendage torsion: varying echogenicity of the torsed appendage according to the time from onset.

OBJECTIVES: The purpose of this study was to evaluate sonographic findings in torsed intrascrotal appendages and to assess the effect of the time from symptom onset on echogenicity and the relationship between the time from symptom onset and manual reduction success. METHODS: Thirty-five boys (6-13 years old; mean, 9.9 years) with torsion of an intrascrotal appendage were evaluated. All had painful unilateral scrotal swelling and palpable tender nodules on physical examination and underwent sonography. Thirty-two underwent subsequent manual reduction. Before manual reduction, we assessed the size, echogenicity, appendage blood flow, periappendiceal blood flow, and scrotal swelling. Data were analyzed according to time from symptom onset. After manual reduction, the number of reduction trials, pain relief, size, and blood flow of the appendix testis were assessed. RESULTS: The torsed appendage was hypoechoic in all 17 boys assessed within 24 hours of symptom onset. In boys assessed more than 24 hours after onset, the torsed appendage was hypoechoic in 6, isoechoic in 4, and hyperechoic in 8. Twenty-two of 23 hypoechoic appendages showed a salt-and-pepper pattern. The echogenicity differed significantly between boys assessed within and more than 24 hours after symptom onset (P < .001). The success rates of manual reduction were 90.9% (20 of 22) for hypoechoic appendages, 75.0% (3 of 4) for isoechoic appendages, and 50.0% (3 of 6) for hyperechoic appendages. Sonography revealed increased blood flow and decreased appendage sizes in all boys with successful reduction. CONCLUSIONS: The echogenicity of a torsed appendage changes according to the time from onset. A hyperechoic intrascrotal appendage is associated with later sonography and is a poor predictor of manual reduction success.