Helical computed tomographic incidence and characterization of appendoliths in 100 patients with appendicitis

This study was performed to determine the helical computed tomographic (CT) incidence and characteristics of appendoliths and the cecal bar sign of appendicitis. One hundred consecutive positive and 100 consecutive negative appendiceal CT scans were reviewed. Appendolith presence, number, size, shape, calcification and air pattern, density, and location were assessed, and the cecal bar, when present, was noted.In 44% of positive appendiceal CT scans, there was one (30) or more (14) calcified appendolith(s), 8.0 mm in mean diameter. Characteristics included round (43.1%), oval (46.6%), or irregular (10.3%) shape; homogeneous (60.3%), rim (36.2%), or irregular (3.5%) calcifications; matrix air (15.5%); and Hounsfield unit (HU) densities (–161 HU to +1368 HU). Locations included proximal (36.2%), middle (44.8%), and distal (19.0%) third of the appendix. A cecal bar was present in 47.6% of proximal appendolith cases.Appendoliths vary in size, shape, calcification and air patterns, density, and location and are present in 44% of positive appendicitis cases at helical CT. A cecal bar separates proximal appendoliths, when present, from cecal contrast medium.     

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     

A new helical computed tomographic technique for appendiceal imaging: Preliminary experience with the focused appendix computed tomographic examination

Our objective was to describe a new, helical computed tomographic (CT) technique for evaluating appendicitis, the focused appendix CT (FACT), and report preliminary experience with its use.Thirty-five consecutive patients were selected on the basis of clinical suspicion for appendicitis. Patients received oral and colon contrast media but not intravenous contrast medium before CT scanning. A thinsection, contiguous helical scan limited to the lower abdomen and upper pelvis was performed. Each scan was interpreted as positive or negative for appendicitis, and any alternative pathology was noted, if present.Seventeen patients had a final diagnosis of appendicitis at surgery and pathology, and 18 patients had appendicitis excluded at clinical follow-up for at least 3 months (17 patients) or at surgeryand pathology (1 patient). FACT interpretations were correct in all cases. Alternative pathology was noted in 13 of the 18 cases (72%) interpreted as negative for appendicitis.     

Limited cone-beam computed tomography imaging of the middle ear: a comparison with multislice helical computed tomography

Purpose: To determine the applicability of cone-beam computed tomography (CBCT) in otological imaging, and to compare its accuracy with the routinely used multislice helical CT (MSCT) for imaging of the middle- and inner-ear areas.

Material and Methods: Thirteen unoperated human cadaver temporal bones were imaged with CBCT and MSCT. Sixteen landmarks of the middle and adjacent inner ear were evaluated and compared for their conspicuity according to a modified Likert scale. Total scores and scores for subgroups including landmarks of specific clinical interest were also compared.

Results: No significant differences were found between the imaging techniques or subgroups when scores of individual structures were compared. While the middle ear itself was visible in all cases with CBCT, parts of the inner ear were “cut off” in four cases due to the limited field of view. For the same reason, the evaluation of the whole mastoid was not possible with CBCT. The cochlear and vestibular aqueducts were not visualized in either CT techniques. The contrast-to-noise ratio was more than 50% lower in CBCT than in MSCT, but still adequate for diagnostic task.

Conclusion: CBCT proved to be at least as accurate as routinely used MSCT in revealing the clinically and surgically important middle-ear structures. The results show that high-quality imaging of the middle ear is possible with the current CBCT device.     

Displacement of coils into the lung during embolotherapy: clinical importance and follow-up with helical CT

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the clinical importance and computed tomographic (CT) appearance of coils displaced into the lung during embolotherapy. MATERIALS AND METHODS: The authors retrospectively studied clinical charts and serial chest images from 25 consecutive patients after coil embolization. Chest radiography was performed in all patients, whereas helical chest CT was performed only in patients in whom dislocated coils were visible on chest radiographs. Coils were applied for the treatment of peripheral arteriovenous (AV) malformations and fistulas (n = 9), renal AV malformations or fistulas (n = 8), and primary or secondary tumors (n = 8). Clinical charts were analyzed for short- and long-term symptoms; chest radiographs and CT scans were reviewed for signs indicative of pulmonary infarction. RESULTS: None of the patients had clinical symptoms suggestive of pulmonary infarction. In two of the 25 patients (8%), displaced coils were seen in the pulmonary vasculature at chest radiography; these patients had been treated for renal AV fistula and peripheral AV fistula, respectively. One patient had two coils in the left hemithorax (upper and lower lobe), and the other patient had two coils in the right hemithorax (middle lobe). Neither of the patients had abnormalities suggestive of pulmonary infarction at helical CT. CONCLUSION: Chest radiography can help confirm the presence of coils displaced to the pulmonary vasculature during embolotherapy. Helical CT can also help rule out the presence of coil-associated pulmonary infarction.     

Effect of ultrasonography and optional computed tomography on the outcome of appendectomy

The aim of this study was to investigate the value of US and complementary CT in patients with suspected appendicitis, and to detect adverse outcomes of preoperative imaging. We retrospectively reviewed the data of 233 consecutive patients who underwent an appendectomy as an emergency procedure in our hospital, within a 2-year period. Our hospital policy is to perform diagnostic imaging in all patients with clinical suspicion of appendicitis. The US was performed in 227 patients, followed by additional unenhanced helical focused appendiceal CT in 30 patients with equivocal US results. We evaluated the negative appendectomy rate, occurrence of perforation, and our in-hospital delay. Acute appendicitis was pathologically proven in 219 patients, corresponding to a negative appendectomy rate of 6%. The US with optional CT diagnosed appendicitis with a sensitivity of 96.7%. Forty-eight appendices (21.9%) were perforated. The median overall in-hospital delay was 5 h (range 0.5–123.5 h). For the perforated appendices this was 4.5 h (range 0.5–64.5 h), for the non-perforated appendices 6.0 h (range 0.5–123.5 h). In patients with suspected acute appendicitis, US examination with the option of additional CT significantly lowers the negative appendectomy rate as compared with the clinical acumen alone, without adverse effects on the perforation rate or the in-hospital delay.     

Low-high and high-low biphasic injection forms in computed tomography examinations of the upper abdomen

Purpose: To analyze the influence of different biphasic and monophasic injection rate protocols in abdominal computed tomography (CT).

Material and Methods: A randomized, consecutive, parallel group study was designed and conducted in 60 patients studied with the same CT helical protocol. Patients were randomly distributed into three groups: (A) monophasic (120 ml at 2.5 ml/s); (B) low-high biphasic (120 ml, first 60 ml at a rate of 2 ml/s, the other 60 ml at 2.5 ml/s); and (C) high-low biphasic (120 ml, first 60 ml at a rate of 2.5 ml/s, the other 60 ml at 2 ml/s). All patients were injected with 300 mg I/ml non-ionic contrast media at a fixed delay time of 55 s. Contrast enhancement efficacy was evaluated by attenuation coefficient measurements.

Results: Although non-significant, monophasic protocol enhancements were higher than biphasic protocol enhancements in all measurements except aortic bifurcation (p = 0.003). At this level, biphasic protocols obtained an increased mean enhancement from 7.6% to 2.5% compared to monophasic protocols.

Conclusion: Monophasic contrast agent injection in helical CT of the upper abdomen produces a higher enhancement of parenchymal and venous structures. No significant difference was observed between low-high and high-low biphasic protocols.     

Clearing the cervical spine in multiple trauma victims: A time-effective protocol using helical computed tomography

This study was performed to evaluate helical computed tomography (HCT) as the primary method of initial cervical spine assessment in multiple trauma victims. Prospective evaluation of the cervical spine using HCT and plain film radiography (PFR) was performed in 800 patients with suspected multisystem injuries. With HCT, an average of 32 slices were obtained at 5-mm intervals from the base of the skull to T1 using helical acquisition and a bone algorithm. HCT was performed following cross-table lateral radiographs of the cervical spine in all patients. We compared HCT and PFR for detection of abnormalities and duration of examination and also compared HCT with conventional CT in a subset of patients (N=20) for image quality/lesion detectability. Sixty-eight fractures were identified in 46 patients. HCT prospectively identified 67 fractures (98.5%), and plain films demonstrated 29 fractures (43%). No difference in image quality/lesion detectability was encountered when comparing HCT to conventional CT. HCT of the cervical spine could be completed in 4.5 minutes and added an average of only 8 minutes to the stay of the patient in the CT room. During the time of the study, the overall patient disposition time from the trauma resuscitation area was reduced from 6.5 to 4.5 hours. Rapid and accurate evaluation of the cervical spine is possible with HCT and is recommended as part of the initial imaging protocol in multiple trauma patients.     

Right lower quadrant pain: Imaging with computed tomography

Computed tomography (CT) is a fast and accurate way to evaluate patients with acute right lower abdominopelvic pain. In the emergency setting, appendicitis is the most common etiology. A tailored CT examination can visualize the normal or abnormal appendix with accuracy, confirming or excluding appendicitis in 90–95% of cases. If the appendix is normal, CT often identifies an alternative etiology for the pain. This exhibit reviews the CT appearance of the normal appendix, usual and unusual presentations of appendicitis and complicated appendicitis, and pitfalls in diagnosis. The CT appearance of other conditions included in the differential diagnosis of acute right lower quadrant pain and clinically mimicking appendicitis is also presented, including disorders arising from the gastrointestinal tract, genitourinary tract, and vascular and musculoskeletal systems.     

The Quality of Reconstructed 3D Images in Multidetector-Row Helical CT: Experimental Study Involving Scan Parameters

Objective

To determine which multidetector-row helical CT scanning technique provides the best-quality reconstructed 3D images, and to assess differences in image quality according to the levels of the scanning parameters used.

Materials and Methods

Four objects with different surfaces and contours were scanned using multidetector-row helical CT at three detector-row collimations (1.25, 2.50, 5.00 mm), two pitches (3.0, 6.0), and three different degrees of overlap between the reconstructed slices (0%, 25%, 50%). Reconstructed 3D images of the resulting 72 sets of data were produced using volumetric rendering. The 72 images were graded on a scale from 1 (worst) to 5 (best) for each of four rating criteria, giving a mean score for each criterion and an overall mean score. Statistical analysis was used to assess differences in image quality according to scanning parameter levels.

Results

The mean score for each rating criterion, and the overall mean score, varied significantly according to the scanning parameter levels used. With regard to detector-row collimation and pitch, all levels of scanning parameters gave rise to significant differences, while in the degree of overlap of reconstructed slices, there were significant differences between overlap of 0% and of 50% in all levels of scanning parameters, and between overlap of 25% and of 50% in overall accuracy and overall mean score. Among the 18 scanning sequences, the highest score (4.94) was achieved with 1.25 mm detector-row collimation, 3.0 pitch, and 50% overlap between reconstructed slices.

Conclusion

Comparison of the quality of reconstructed 3D images obtained using multidetector-row helical CT and various scanning techniques indicated that the 1.25 mm, 3.0, 50% scanning sequence was best. Quality improved as detector-row collimation decreased; as pitch was reduced from 6.0 to 3.0; and as overlap between reconstructed slices increased.     

Ureterolithiasis: classical and atypical findings on unenhanced helical computed tomography

Evaluation of patients with acute flank pain using helical computed tomography (CT) is a well-accepted, rapid, and safe procedure in the emergency setting. Various primary and secondary signs are described in the literature for evaluation of these patients. Our purpose is to demonstrate both the classical findings associated with ureteral calculi on unenhanced helical CT and atypical findings and potential pitfalls. We also provide readers with a systematic approach to interpreting unenhanced helical CT scans performed for acute flank pain. Electronic Publication     

Multiphasic Perfusion CT in Acute Middle Cerebral Artery Ischemic Stroke: Prediction of Final Infarct Volume and Correlation with Clinical Outcome

Objective

To assess the utility of multiphasic perfusion CT in the prediction of final infarct volume, and the relationship between lesion volume revealed by CT imaging and clinical outcome in acute ischemic stroke patients who have not undergone thrombolytic therapy.

Materials and Methods

Thirty-five patients underwent multiphasic perfusion CT within six hours of stroke onset. After baseline unenhanced helical CT scanning, contrast-enhanced CT scans were obtained 20, 34, 48, and 62 secs after the injection of 90 mL contrast medium at a rate of 3 mL/sec. CT peak and total perfusion maps were obtained from serial CT images, and the initial lesion volumes revealed by CT were compared with final infarct volumes and clinical scores.

Results

Overall, the lesion volumes seen on CT peak perfusion maps correlated most strongly with final infarct volumes (R²=0.819, p<0.001, slope of regression line=1.016), but individual data showed that they were less than final infarct volume in 31.4% of patients. In those who showed early clinical improvement (n=6), final infarct volume tended to be overestimated by CT peak perfusion mapping and only on total perfusion maps was there significant correlation between lesion volume and final infarct volume (R²=0.854, p=0.008). The lesion volumes depicted by CT maps showed moderate correlation with baseline clinical scores and clinical outcomes (R=0.445-0.706, p≤0.007).

Conclusion

CT peak perfusion maps demonstrate strong correlation between lesion volume and final infarct volume, and accurately predict final infarct volume in about two-thirds of the 35 patients. The lesion volume seen on CT maps shows moderate correlation with clinical outcome.     

Improved pelvicalyceal visualization with multidetector computed tomography urography; comparison with helical computed tomography

Our aim was to compare the quality of pelvicalyceal visualization on computed tomography (CT) urography using a small intravenous contrast material dose, hydration, and high-resolution multidetector CT (MDCT) with that of conventional helical CT. The test (MDCT) group (49 consecutive patients, 98 kidneys) was scanned 5 min following an intravenous bolus of 30 ml of iodinated contrast material. The control (helical CT) group (50 consecutive patients, 95 kidneys) was scanned 5 min following injection of 120–150 ml of intravenous contrast material. Enhancement and quality of calyceal detail were measured using a five-scale grading system (1 for no detail, 5 for cupped calyces). Calyceal attenuation was substantial in both groups (more than 220 Hounsfield units, HU) but less in the test group compared with the control group (mean 475 and 920 HU, respectively), p<0.0001. In the test group, the calyceal attenuation was less than 500 HU in the majority of cases (65/98 kidneys), while the opposite was true for the control group, where calyceal attenuation was more than 750 HU in 50/95 kidneys (p<0.001). The quality of calyceal detail was 3.4/5 in the test group compared with 1.8/5 in the control group (p<0.0001). The combination of hydration, low-contrast dose, and the high image resolution achieved with MDCT significantly improves calyceal visualization in CT urography.     

Complications of acute pancreatitis: helical CT evaluation

Acute pancreatitis represents one of the more commonly encountered etiologies of acute abdominal pain. Many complications can present emergently, including pancreatic abscess, necrosis, and hemorrhage. The purpose of this pictorial essay is to educate the reader about the spectrum of CT findings in patients with complications from pancreatitis. Emphasis is placed on evaluation with helical CT, stressing optimal technique and the imaging parameters essential for accurate diagnosis.     

Interventricular septal mass: an unusual manifestation of sarcoidosis demonstrated on helical computed tomography

The diagnosis of cardiac sarcoidosis can be difficult to establish. We present the case of a 33-year-old woman in whom a contrast-enhanced helical computed tomographic examination of the thorax demonstrated an interventricular septal mass. Subsequent open biopsy confirmed cardiac sarcoidosis.     

Esophageal and gastric vasculature in children with extrahepatic portal hypertension: evaluation by intravenous CT portography

PURPOSE: To compare the findings related to esophageal/gastric varices and congestive gastropathy on intravenous computed tomography (CT) portography (CTP) and upper gastrointestinal endoscopy (UGIE) in children with extrahepatic portal venous obstruction (EHO) presented with hematemesis. METHODS/MATERIALS: Fifty pediatric patients (age < 15 years) with EHO (initially diagnosed on abdominal ultrasound) presented with hematemesis and underwent UGIE and intravenous CTP using a helical CT scanner. Axial sections of 2 mm each were obtained with a collimation of 2 mm and a table feed of 3 mm. CTP findings on these axial sections were compared with UGIE (gold standard). RESULTS: The sensitivity of CTP for detection of esophageal varices, gastric varices, and gastropathy was 32/33 (97%), 38/40 (95%), and 30/32 (93%), respectively. CTP showed false positivity as well, which was 5/17 (29%), 2/10 (20%), and 13/17 (76%) for esophageal varices, gastric varices, and gastropathy, respectively. On follow-up UGIE, the endoscopic features appeared in 14/19 (74%) of false positive patients. Therefore, false positivity for all the parameters on CTP when compared to the initial UGIE represented the changes in vasculature before they were endoscopically manifest. CONCLUSIONS: CTP was likely to pick up changes in esophageal and gastric vasculature earlier than UGIE in children with EHO presented with hematemesis.     

Advances in cardiac imaging with 16-section CT systems

RATIONALE AND OBJECTIVES: The authors present advances in electrocardiographically (ECG) gated cardiac spiral scanning with recently introduced 16-section computed tomographic (CT) equipment. MATERIALS AND METHODS: The authors discuss the technical principles of ECG-gated cardiac scanning. They give an overview on system properties and on the detector design. They describe ECG-gated scan- and image-reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose. They discuss key parameters for image quality and present simulation and phantom studies and they give preliminary values for the patient dose. RESULTS: An extension of the adaptive cardiac volume reconstruction for ECG-gated spiral CT provides adequate image quality for up to 16 sections. With the smallest reconstructed section width (about 0.83 mm) and overlapping image reconstruction, cylindrical holes 0.6-0.7 mm in diameter can be resolved in a transverse resolution phantom independent of the heart rate. For coronary CT angiography, the influence of transverse resolution is most pronounced for coronary segments that are only slightly tilted relative to the scan plane. In this case, visualization of stents and plaques is considerably improved with 1.0-mm or smaller section width. For 0.42-second gantry rotation time, temporal resolution reaches its optimum (105 msec) at a heart rate of 81 beats per minute. Effective patient dose for the standard protocols recommended by the manufacturer ranges from 0.45 mSv (male) for ECG-triggered calcium scoring to 7.1 mSv (male) for high-resolution ECG-gated coronary CT angiography. With ECG pulsing, the dose is reduced by 30%-50% depending on the patient's heart rate. CONCLUSION: Clinical experience will be needed to evaluate fully the potential of 16-section technology for cardiac imaging.     

Cost reduction in abdominal CT by weight-adjusted dose

Aim

To analyze the influence of contrast dose adjusted by weight vs. fixed contrast dose in the attenuation and cost of abdominal computed tomography (CT).

Materials and methods

A randomised, consecutive, parallel group study was conducted in 151 patients (74 men and 77 women, age range 22–67 years), studied with the same CT helical protocol. A dose at 1.75 ml/kg was administered in 101 patients while 50 patients had a fixed dose of 120 ml of same non-ionic contrast material (320 mg/ml). Mean enhancements were measured at right hepatic lobe, superior abdominal aorta and inferior cava vein. Statistical analysis was weight-stratified (<60, 61–70, 71–80 and >81 kg).

Results

Aortic attenuation was significantly superior (p < 0.05) in the dose adjusted by weight group than in the fixed dose group. Patients who weighed >61 kg in dose-adjusted group, presented higher hepatic attenuation, being statistically significant in those >81 kg (p < 0.01). In dose-adjusted group, there was a savings of €4.1 per patient in patients weighing <80 kg. In patients weighing >80 kg, there was an over cost of €10.7 per patient.

Conclusions

An injection volume of 1.75 ml/kg offers an optimal diagnostic quality with a global savings of €1.34 per patient.