Comparison of CT and sonography in the diagnosis of acute appendicitis: a blinded prospective study

OBJECTIVE: Our objective was to compare the accuracy of CT and sonography in a general community teaching hospital for the diagnosis of acute appendicitis in patients with suspected acute appendicitis. SUBJECTS AND METHODS. In this prospective study, 199 consecutive patients with clinical signs and symptoms of acute appendicitis were examined with sonography (graded compression technique) and CT (focused unenhanced single-detector helical CT [5-mm section thickness]. CT was performed from the L2 vertebral body to the pubic symphysis, and no patients were given oral, rectal, or IV contrast medium. The primary sonographic criterion for diagnosing acute appendicitis was an incompressible appendix with a transverse outer diameter of 6 mm or larger with incompressible periappendicular inflamed fat with or without an appendicolith. The primary CT criterion for diagnosing acute appendicitis was the identification of an appendix with a transverse outer diameter of 6 mm or larger with associated periappendiceal inflammatory changes. The results, independently reported, were correlated with surgical and histopathologic findings. RESULTS: One hundred thirty-two patients had acute appendicitis at surgery, and 67 patients did not. The sensitivity of CT and sonography was 76% and 79%, respectively; the specificity was 83% and 78%; the accuracy was 78% and 78%; the positive predictive value was 90% and 87%; and the negative predictive value was 64% and 65%. CONCLUSION: Unenhanced focused single-detector helical CT and graded compression sonography performed in a general community teaching hospital by both body imaging radiologists and general radiology staff members have a similar accuracy for the diagnosis of acute appendicitis.     

CT evaluation of appendicitis and its complications: imaging techniques and key diagnostic findings

OBJECTIVE: This article reviews various CT protocols for appendicitis, identifies key CT findings for diagnosing appendicitis, discusses unusual manifestations such as chronic and recurrent appendicitis, and profiles imaging features that differentiate appendicitis from other inflammatory and neoplastic ileocecal conditions. Patients were studied with helical CT. CONCLUSION: CT is a highly accurate, noninvasive test for appendicitis, but the optimal CT technique is controversial. Major complications of appendicitis (perforation, abscess formation, peritonitis, bowel obstruction, septic seeding of mesenteric vessels, gangrenous appendicitis) and their management are discussed. Abdominal CT is a well-established technique in the study of acute abdominal pain and has shown high sensitivity and specificity for diagnosing and differentiating appendicitis, providing an accurate diagnosis in the early stages of disease.     

Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients.

PURPOSE: To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis. MATERIALS AND METHODS: Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both. RESULTS: There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%. CONCLUSION: Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.     

Imaging strategies in children with suspected appendicitis

Appendicitis is the commonest acute surgical emergency of childhood, and occurs in approximately 2-4 per 1000 infants. It is usually seen in infants older than 5 years but can occur at any age. Atypical clinical findings are seen in 30-50% of children, especially the younger ones, and often leads to a delayed diagnosis. Preoperative clinical assessment alone has yielded an accuracy ranging between 70 and 90% but is associated with a normal appendectomy rate of 13-25%. Preoperative imaging using the graded compression US technique and/or different helical CT techniques has been able to reduce this rate to 3-7% without an increase in perforation rate. An extensive review of the literature revealed several papers examining the accuracy of different imaging modalities and strategies of acute appendicitis in children. The reported sensitivity of US varied between 87 and 95%, vs 95-97% for helical CT, while the specificity ranged between 85 and 98% for US and 94 and 97% for helical CT. Only one truly randomised study was found, showing that compared with US alone, a combination of US and helical CT increased the sensitivity from 86 to 99%, while the specificity decreased from 95 to 89%. We conclude that imaging should be performed in all children with suspected appendicitis and that US should be the initial procedure with CT as a complementary tool.     

Evaluation of suspected appendicitis in children and young adults: helical CT

PURPOSE: To evaluate the accuracy of helical computed tomography (CT) for the diagnosis of appendicitis in children and to assess the utility of CT in establishing alternative diagnoses. MATERIALS AND METHODS: The medical records of 154 children (median age, 12 years; age range, 1-20 years) who were suspected to have appendicitis and who underwent CT were reviewed. The gastrointestinal tract was opacified in 151 of 154 patients: Only orally administered contrast material was used in 126 patients; only rectally administered contrast material, in 21 patients; and both oral and rectal contrast material, in four patients. CT findings were correlated with surgical and histopathologic findings or with clinical follow-up findings. RESULTS: Sixty-four CT scans were interpreted as positive for appendicitis and included 58 true-positive and six false-positive scans. Ninety scans were interpreted as negative and included 87 true-negative and three false-negative scans. CT had a sensitivity of 95% and a specificity of 94% for the diagnosis of appendicitis. In addition, in 32 (34%) of 93 patients without appendicitis, an alternative diagnosis was established on the basis of CT findings. CONCLUSION: Helical CT is useful in a pediatric population to diagnose or exclude appendicitis and to establish an alternative diagnosis.     

Appendicolith revealed on CT in children with suspected appendicitis: how specific is it in the diagnosis of appendicitis?

OBJECTIVE. The purpose of this study was to determine the sensitivity, specificity, and positive and negative predictive values of a diagnosis of appendicitis when CT without enteric contrast material reveals an appendicolith in children with suspected appendicitis. MATERIALS AND METHODS. A retrospective review of children who underwent abdominal CT for suspected appendicitis over a 25-month period was performed to identify patients with an appendicolith. An age-matched group of patients examined for trauma served as controls. RESULTS. CT was performed in 104 children. Appendicitis was present in 60 (58%) of 104 children; 39 (65%) of 60 had an appendicolith. Appendicitis was not present in 44 (42%) of 104; six (14%) of 44 had an appendicolith. An appendicolith detected on CT had a sensitivity of 65% and a specificity of 86% for the radiologist diagnosing appendicitis. An appendicolith had a positive predictive value of 74% and a negative predictive value of 26%. Among the control population, two (3%) of 74 children had an appendicolith. This number was statistically significant compared with children in the study group with an appendicolith and abdominal pain, but without appendicitis (p = 0.02). CONCLUSION. Although an appendicolith is significantly associated with appendicitis, the detection of an isolated appendicolith on CT is not sufficiently specific to be the sole basis for the diagnosis of acute appendicitis.     

Imaging strategies in children with suspected appendicitis

Appendicitis is the commonest acute surgical emergency of childhood, and occurs in approximately 2–4 per 1000 infants. It is usually seen in infants older than 5 years but can occur at any age. Atypical clinical findings are seen in 30–50% of children, especially the younger ones, and often leads to a delayed diagnosis. Preoperative clinical assessment alone has yielded an accuracy ranging between 70 and 90% but is associated with a normal appendectomy rate of 13–25%. Preoperative imaging using the graded compression US technique and/or different helical CT techniques has been able to reduce this rate to 3–7% without an increase in perforation rate. An extensive review of the literature revealed several papers examining the accuracy of different imaging modalities and strategies of acute appendicitis in children. The reported sensitivity of US varied between 87 and 95%, vs 95–97% for helical CT, while the specificity ranged between 85 and 98% for US and 94 and 97% for helical CT. Only one truly randomised study was found, showing that compared with US alone, a combination of US and helical CT increased the sensitivity from 86 to 99%, while the specificity decreased from 95 to 89%. We conclude that imaging should be performed in all children with suspected appendicitis and that US should be the initial procedure with CT as a complementary tool.     

Imaging evaluation of suspected appendicitis in a pediatric population: effectiveness of sonography versus CT

OBJECTIVE. The purpose of this study was to compare the diagnostic accuracy of graded compression sonography with that of helical CT for the diagnosis of appendicitis in a pediatric and young adult population. SUBJECTS AND METHODS. Between June 1996 and April 1999, 386 pediatric and young adult patients with suspected appendicitis were examined using sonography, CT, or both: 233 underwent sonography only, 71 underwent CT only, and 82 underwent sonography and CT. All sonograms and CT scans were prospectively interpreted as showing positive or negative findings for appendicitis by one of six pediatric radiologists. CT and sonographic findings were correlated with surgical and histopathologic findings or findings at clinical follow-up. RESULTS. Helical CT had a significantly higher sensitivity (95% versus 78%, p = 0.009) and accuracy (94% versus 89%, p = 0.05) than graded compression sonography for the diagnosis of appendicitis in children, adolescents, and young adults. The specificity of both techniques was 93%. Twenty of 82 patients who underwent both sonography and CT had discordance between the findings of the two examinations. The CT results were correct in a significantly greater number of patients with discordant examinations (17/20 patients [85%]). CONCLUSION. Helical CT has a significantly higher sensitivity and accuracy than graded compression sonography for the diagnosis of appendicitis in a pediatric and young adult population, particularly in children more than 10 years old.     

Accuracy of nonfocused helical CT for the diagnosis of acute appendicitis: a 5-year review

OBJECTIVE: The clinical usefulness of routine, nonfocused helical CT was evaluated in diagnosing acute appendicitis or providing an alternative diagnosis in patients presenting to the emergency department with acute lower abdominal pain. MATERIALS AND METHODS: We reviewed CT reports and clinical records of 650 consecutive adult patients who presented between January 1996 and December 2000 with right lower quadrant pain or lower abdominal pain and clinical findings suggestive of appendicitis. Helical CT was performed with oral contrast material in 610 cases (93.8%) and IV contrast in 572 cases (88.0%). Both vascular and enteric contrast media were administered in 544 cases (83.7%). Rectal contrast material was administered in 52 cases (8.0%). The abdomen was helically scanned from the dome of the diaphragm to the iliac crests with a collimation of 7 mm, from the iliac crests to the acetabular roof at a 5-mm collimation, from the acetabular roof to the symphysis pubis with a collimation of 5-10 mm. The surgical or clinical record was used for follow-up. RESULTS: Of the 650 patients, 552 (84.9%) had adequate clinical follow-up. There were 137 true-positive, eight false-positive, five false-negative, and 402 true-negative cases. The sensitivity, specificity, and accuracy of nonfocused helical CT were 96.5%, 98.0%, 97.6%, respectively. The positive and negative predictive values were 94.5% and 98.8%, respectively. In patients without acute appendicitis, CT suggested an alternative diagnosis, which clinically explained the patient's acute abdominal pain in 266 patients (66.2%). CONCLUSION: Nonfocused helical CT was highly accurate in diagnosing acute appendicitis or suggesting an alternative diagnosis in patients with acute lower abdominal pain or right lower quadrant pain.     

Diagnosis of acute appendicitis with unenhanced helical CT: a study of 130 patients

The aim of this study was to determine the sensitivity, specificity, and diagnostic accuracy of helical computed tomography (CT) without oral, intravenous, or rectal administration of contrast material in confirming the diagnosis of acute appendicitis in patients with suggestive clinical and laboratory findings. One hundred and thirty patients with suspected acute appendicitis underwent an unenhanced helical CT scan. Scans were obtained in a single breath-hold from the level of umbilicus to the pubic symphysis using a 5-mm collimation. Oral, intravenous, or rectal contrast materials were not used. The criteria for diagnosis of acute appendicitis included an enlarged diameter of appendix more than 6 mm with associated periappendiceal inflammation. The results yielded a sensitivity of 94.7%, a specificity of 91.7%, an accuracy of 93.8%, a positive predictive value of 96.7%, and a negative predictive value of 86.8%. Unenhanced helical CT accurately diagnoses acute appendicitis, and it protects the patients from unnecessary further time-consuming diagnostic procedures, the risks associated with contrast material administration, and unnecessary surgical interventions. Electronic Publication     

Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material

PURPOSE: To compare the diagnostic accuracy of focused helical computed tomography (CT) with orally administered contrast material with that of nonfocused helical CT with orally and intravenously administered contrast material. MATERIALS AND METHODS: After receiving oral contrast material, 228 patients with clinically suspected appendicitis underwent focused appendiceal CT (5-mm section thickness, 15-cm coverage in the right lower quadrant). Immediately thereafter, helical CT of the entire abdomen and pelvis was performed following intravenous administration of contrast material (abdomen, 7-mm section thickness; pelvis, 5-mm section thickness). Studies were separated and independently interpreted by three observers who were blinded to patient names. Diagnoses were established by means of surgical and/or clinical follow-up findings. RESULTS: Fifty-one (22.4%) of 228 patients had acute appendicitis. Readers diagnosed appendicitis with 83.3%, 73.8%, and 71.4% sensitivity and 93.0%, 92.3%, and 97.9% specificity with focused nonenhanced appendiceal CT. Readers diagnosed appendicitis with 92.9%, 92.9%, and 88.1% sensitivity and 93.7%, 95.1%, and 96.5% specificity with nonfocused enhanced CT. Summary areas under the receiver operating characteristic curve estimates for focused nonenhanced and nonfocused enhanced CT were 0.916 and 0.964, respectively; the differences were statistically significant (P <.05) for two of three readers. All readers demonstrated higher sensitivities for detecting the inflamed appendix with nonfocused enhanced CT. Appendicitis was missed with focused CT in two patients whose inflamed appendix was not included in the imaging of the right lower quadrant. All readers were significantly more confident in diagnosing alternative conditions with nonfocused enhanced CT. CONCLUSION: Diagnostic accuracy of helical CT for acute appendicitis improved significantly with use of intravenous contrast material.     

非增强螺旋CT扫描对急性阑尾炎的诊断价值

目的 评价非增强螺旋CT扫描对急性阑尾炎的诊断价值。资料与方法 对115例临床怀疑急性阑尾炎患者作非增强螺旋CT扫描，不口服或结肠内灌注对比剂，层厚10mm，Pitch1，扫描范围从L3椎体至耻骨联合。CT诊断急性阑尾炎的标准包括阑尾增粗横径超过6mm，或阑尾结石同时伴有阑尾周围的炎性改变。CT诊断结果与手术、病理或临床随访结果进行对照。结果 CT发现56例真阳性，49例真阴性，7例假阴性和3例假阳性。CT诊断急性阑尾炎的敏感性为89％，特异性为94％，准确性为91％，阳性预测值为95％，阴性预测值为88％。49例无阑尾炎患者中，CT发现其他病变22例(45％)。结论 非增强螺旋CT扫描，能快速、准确地诊断有无急性阑尾炎，而且还能发现除阑尾炎以外的其他各种病变。     

Diagnostic value of unenhanced helical CT in adult patients with suspected acute appendicitis

Clinical diagnosis of appendicitis is usually made on the basis of history, physical examination and laboratory studies. Approximately 30-45% of patients with suspected appendicitis present with atypical clinical and laboratory findings. Recently graded compression ultrasound and thin section unenhanced helical CT have been used to establish diagnosis for patients with suspected acute appendicitis. The purpose of this study was to determine the diagnostic accuracy of thin section unenhanced helical CT protocol in adult patients with suspected acute appendicitis. CT scans obtained when patients presented with right lower quadrant pain and the clinical impression was equivocal for appendicitis were evaluated. Of 296 patients referred for CT, 123 patients subsequently underwent surgery. Appendicitis had been correctly predicted in 104 of 108 patients surgically proven to have appendicitis. Unenhanced helical CT in the diagnosis of acute appendicitis had a sensitivity of 96%, specificity of 98%, positive predictive value of 97% and negative predictive value of 98%. If no definite inflammatory changes are detected, on the basis of our experience we recommend that the patient be monitored clinically, and that thin section unenhanced helical CT is the optimal technique to detect acute appendicitis in adult patients.     

Helical CT of appendicitis and diverticulitis.

The clinical diagnosis of appendicitis and diverticulitis remains challenging. Clinical diagnosis alone can lead to unnecessary hospitalizations and surgeries, prolonged periods of hospital observation, and delays prior to necessary medical or surgical treatment. Helical CT combined with recently reported techniques for imaging appendicitis and diverticulitis offers rapid and accurate confirmation or exclusion of these entities as well as identification of alternative conditions that can clinically mimic them. More routine use of helical CT holds great promise for improving patient care and lowering hospital resource use in patients with clinically suspected appendicitis and diverticulitis.     

Appendicitis at the millennium

Acute appendicitis is a common clinical problem. Accurate and prompt diagnosis is essential to minimize morbidity. While the clinical diagnosis may be straightforward in patients who present with classic signs and symptoms, atypical presentations may result in diagnostic confusion and delay in treatment. Helical computed tomography (CT) and graded compression color Doppler ultrasonography (US) are highly accurate means of establishing the diagnosis. These imaging modalities have now assumed critical roles in the treatment of patients suspected to have appendicitis. The purpose of this article is threefold: to provide an update on new information regarding the pathophysiology, clinical diagnosis, and laparoscopic treatment of acute appendicitis; to describe the state-of-the art use of CT and US in diagnosing this disease entity; and to address the role of medical imaging in this patient population.     

Accuracy of Nonenhanced CT vs Contrast-Enhanced CT for Diagnosis of Acute Appendicitis in Adults

BackgroundAcute appendicitis is one of the most common causes of acute abdominal pain requiring emergency intervention. It is often difficult for the clinician to make an accurate diagnosis due to nonspecific and overlapping clinical symptoms. Computed tomography (CT) has become the imaging modality of choice for the evaluation of suspected acute appendicitis. The main purpose of our study was to compare nonenhanced CT (NECT) with contrast-enhanced CT (CECT) for the diagnosis of acute appendicitis.Material and MethodsA total of 140 patients were enrolled in the study. Two abdominal radiologists—masked to both the clinical information and the final diagnosis—retrospectively reviewed the computed tomographic findings and made an imaging diagnosis based on (1) NECT only, (2) CECT only, and (3) both NECT and CECT. With the final diagnosis as the reference standard, the accuracy of each CT technique was estimated.ResultsThe respective sensitivity, specificity, and accuracy for NECT, CECT, and NECT + CECT for the diagnosis of acute appendicitis were 80.7%, 86.7%, and 84.3%; 86.0%, 81.9%, and 83.6%; and, 87.7%, 80.7%, and 83.6%. There was no significant difference in the diagnosis of acute appendicitis among the 3 techniques. In order to make a correct diagnosis, the presence of at least 3 imaging findings for NECT or at least 4 for CECT had the best diagnostic accuracy. We also found that 9.25 mm was the optimal cut-off threshold for the detection of patients with acute appendicitis.ConclusionOur study allowed direct comparison between NECT, CECT, and NECT + CECT combined. There was no difference in the ability of each CT technique for diagnosing patients with acute appendicitis. For a patient whom iodinated contrast media is contraindicated or a patient who has an increased risk of severe adverse reaction, we would encourage the use of NECT because it provides comparable diagnostic accuracy without further exposing such patient to the contrast media.     

非对比增强CT对临床疑诊急性阑尾炎的诊断准确性（附74例分析）

目的评价非对比增强CT对1临床疑诊急性阑尾炎的诊断准确性。方法74例临床疑诊急性阑尾炎患者均经非对比增强的腹盆部（从L1椎体水平至耻骨联合上缘）螺旋CcT扫描。用于诊断急性阑尾炎的标准为阑尾直径大于6mm和阑尾周围脂肪的炎性改变。最终的CT诊断经手术或临床随访证实。结果74例临床疑诊急性阑尾炎患者中,CT诊断25例真阳性,42例真阴性,4例假阴性和3例假阳性,敏感性为86．2％,特异性为93．3％,准确性为90．5％,阳性预测值为89．3％,阴性预测值为91．3％。结论非对比增强CT对诊断或排除急性阑尾炎具有较高的准确性,并能大幅度地降低阴性阑尾的切除率和不必要的延期观察。     

When appendicitis is suspected in children.

Acute appendicitis is the most common condition requiring emergent abdominal surgery in childhood. The clinical diagnosis of acute appendicitis is often not straightforward because approximately one-third of children with the condition have atypical clinical findings. The delayed diagnosis of this condition has serious consequences, including appendiceal perforation, abscess formation, peritonitis, sepsis, bowel obstruction, and death. Cross-sectional imaging with ultrasonography (US) and computed tomography (CT) have proved useful for the evaluation of suspected acute appendicitis. There has been a great deal of variability in the utilization of these modalities for such diagnosis in the pediatric population. The principal advantages of US are its lower cost, lack of ionizing radiation, and ability to assess vascularity through color Doppler techniques and to provide dynamic information through graded compression. The principal advantages of CT include less operator dependency than US, as reflected by a higher diagnostic accuracy, and enhanced delineation of disease extent in a perforated appendix.     

Patient gender-related performance of nonfocused helical computed tomography in the diagnosis of acute appendicitis

OBJECTIVE: To determine the impact of patient gender on the performance of helical computed tomography (CT) in the diagnosis of acute appendicitis. MATERIALS AND METHODS: From January 1, 1996 to December 31, 2000, 650 consecutive nonfocused helical abdominal CT scans were performed in adult patients presenting with acute lower abdominal pain. In general, most patients received both intravenous and oral contrast with 5-mm scan collimation through the lower abdomen and pelvis; details regarding technique and overall accuracy have been published previously. We subanalyzed results with respect to patient gender-related differences, especially in false-positive and false-negative cases. A chi2 analysis was performed to determine if significant gender-related differences were present in major or minor CT diagnostic criteria for acute appendicitis, extra-appendiceal findings, sensitivity, specificity, and accuracy. RESULTS: Of the 650 patients, 552 had adequate clinical follow-up. The sensitivity for diagnosing acute appendicitis was 100% (65/65) in men and 93.6% (74/79) in women (P < 0.05); specificity was 96.2% (130/135) in men and 98.9% (272/275) in women (P > 0.05); and accuracy was 97.5% (193/198) in men and 97.6% in women (346/354) (P > 0.05). A thickened appendix and periappendiceal stranding were seen in 92.1% of men and 84.5% of women (P = 0.15) All 5 false-negative results were in thin women. In patients without acute appendicitis, CT was able to provide a relevant alternative diagnosis in 183 of 272 women (67.3%) and 81 of 130 men (62.3%) (P > 0.05). CONCLUSION: Nonfocused helical CT was highly accurate for diagnosing acute appendicitis in both men and women, although there was a slight but significant decrease in sensitivity in thin women.     

Suspected appendicitis in children: diagnosis with contrast-enhanced versus nonenhanced Helical CT

PURPOSE: To compare the diagnostic accuracy of limited-area (lower abdominal) nonenhanced helical computed tomography (CT), intravenous contrast material-enhanced helical CT of the entire abdomen, and the combination of both. MATERIALS AND METHODS: Three hundred six children suspected of having appendicitis, who were previously included in a prospective study, underwent limited-area nonenhanced helical CT of the lower abdomen and contrast-enhanced CT of the entire abdomen. No oral or rectal contrast material was administered. The CT scans were retrospectively reviewed by three independent readers both separately and together. The readers were blinded to all clinical information and to the results of previous ultrasonographic and CT examinations. Final diagnoses were established on the basis of surgical, histopathologic, or clinical follow-up findings. The Pearson chi(2) test was performed to compare values between groups. The Student two-sample t test was performed to determine statistically significant differences in age and sex. RESULTS: One hundred twenty-nine patients (42%) had appendicitis. Readers diagnosed appendicitis with 66% pooled sensitivity and 96% pooled specificity with limited-area nonenhanced CT. With contrast-enhanced CT of the entire abdomen, appendicitis was diagnosed with 90% pooled sensitivity and 94% pooled specificity. With both sequences together, readers diagnosed appendicitis with 90% pooled sensitivity and 94% pooled specificity. The difference between the sensitivity of limited-area nonenhanced CT and that of contrast-enhanced CT was statistically significant (P <.001). CONCLUSION: Sensitivity of helical CT for suspected appendicitis in children improved significantly with abdominal contrast-enhanced CT compared with limited-area nonenhanced CT. No further improvement in sensitivity was achieved with the combination of both sequences in comparison to that with contrast-enhanced CT alone.