High-resolution Multislice Computed Tomography Research Articles

Cone Beam CT Versus Multislice CT: Radiologic Diagnostic Agreement in the Postoperative Assessment of Cochlear Implantation.

To evaluate the diagnostic concordance between multislice computed tomography (MSCT) and cone beam computed tomography (CBCT) in the early postoperative assessment of patients after cochlear implantation. Prospective, randomized, single-center, interventional, pilot study on the diagnostic performance of a medical device. Tertiary referral center. Patients aged over 18 years requiring a computed tomographic (CT) scan after cochlear implant surgery. Nine patients were implanted with electrode arrays from three different manufacturers, including one bilateral. High-resolution MSCT and CBCT were then performed, and two experienced radiologists blinded to the imaging modality evaluated the randomized images, twice. Concordance between MSCT and CBCT for assessing the scalar position (tympani or vestibuli) of the electrodes. Secondary outcome measures were also studied: length of the intracochlear electrode array, percentage of implanted cochlea, number of intracochlear electrodes, and radiation doses. There was a good agreement between both CT scanners in determining the scalar position and estimating the number of implanted electrodes and percentage of implanted cochlea. CBCT had a lower radiation exposure. The CBCT appears to be a useful tool for postoperative assessment of cochlear implanted adult patients and is comparable to the conventional scanner in determining the scalar position, with lower radiation exposure.

MSCT versus CBCT: evaluation of high-resolution acquisition modes for dento-maxillary and skull-base imaging.

Our aim was to conduct a quantitative and qualitative evaluation of high-resolution skull-bone imaging for dentistry and otolaryngology using different architectures of recent X-ray computed tomography systems. Three multi-slice computed tomography (MSCT) systems and one Cone-beam computed tomography (CBCT) system were used in this study. All apparatuses were tested with installed acquisition modes and proprietary reconstruction software enabling high-resolution bone imaging. Quantitative analyses were performed with small fields of view with the preclinical vmCT phantom, which permits to measure spatial resolution, geometrical accuracy, linearity and homogeneity. Ten operators performed visual qualitative analyses on the vmCT phantom images, and on dry human skull images. Quantitative analysis showed no significant differences between protocols in terms of linearity and geometric accuracy. All MSCT systems present a better homogeneity than the CBCT. Both quantitative and visual analyses demonstrate that CBCT acquisitions are not better than the collimated helical MSCT mode. Our results demonstrate that current high-resolution MSCT protocols could exceed the performance of a previous generation CBCT system for spatial resolution and image homogeneity. • Quantitative evaluation is a prerequisite for comparison of imaging equipment. • Bone imaging quality could be objectively assessed with a phantom and dry skull. • The current MSCT shows better image quality than a dental CBCT system. • CBCT remains a work-in-progress technology.

A retrospective study of laparoscopic unilateral adrenalectomy for primary hyperaldosteronism caused by unilateral adrenal hyperplasia

To evaluated the long-term outcomes of laparoscopic unilateral adrenalectomy for primary aldosteronism (PA) caused by unilateral adrenal hyperplasia (UAH). One hundred and sixty-four patients who underwent laparoscopic unilateral adrenalectomy for UAH from January 2004 to December 2011 were entered in this retrospective analysis. Patients demographics, perioperative parameters, and follow-up results were recorded and analyzed statistically. All 164 cases suffered hypertension with biochemical evidence of hyperaldosteronism prior to operation. Hypokalemia was observed in 52/164 (37.14%) patients. UAH was proved by multi-slice computed tomography (MSCT). All operations were completed successfully without any conversions or complications. Postoperative pathology confirmed that 164 cases were cortical nodular hyperplasia, of which 4 cases coexist with medullary hyperplasia and 7 with micro-adenoma. At the median follow-up of 48 months, hypertension was cured in 88 (53.7%) patients, improved in 71 (43.3%) patients, and refractory in 5 (3.05%) patients. Hypokalemia and hyperaldosteronism were cured in all patients except re-elevation of blood pressure and plasma aldosterone in two patients 1 month after adrenalectomy. As an underestimated subtype of PA, UAH is accepted gradually. Laparoscopic unilateral adrenalectomy is nowadays the preferred approach to treat patients with PA caused by UAH. When adrenal venous sampling is not allowed, high-resolution MSCT is a reliable test for lateralization of aldosterone hypersecretion in carefully selected patients and 97% had either cure or improvement in blood pressure control.

Accuracy of high-resolution computed tomography in locating facial nerve injury sites in temporal bone trauma

In this study, high-resolution, multislice computed tomography findings are compared with surgical findings in terms of the fracture location in patients with traumatic facial paralysis. Patients with traumatic facial paralysis with grade VI House-Brackmann scale who met the criteria for surgical decompression between 2008 and 2012 were included in this study. All the patients underwent a multislice high-resolution, multislice computed tomography (HRCT) using 1-mm-thick slices with a bone window algorithm. The anatomical areas of the temporal bone (including the Fallopian canal) were assessed by CT and during the surgery (separately by the radiologist and the surgeon), and fracture line involvement was recorded. Forty-one patients entered this study. The perigeniculate area was the most commonly involved region (46.34 %) of the facial nerve. The sensitivity and specificity of HRCT to detect a fracture line seems to be different in various sites, but the overall sensitivity and specificity were 77.5 and 77.7 %, respectively. Although HRCT is the modality of choice in traumatic facial paralysis, the diagnostic value may differ according to the fracture location. The results of HRCT should be considered with caution in certain areas.

State of the Art Hybrid Technology: PET/CT

In the recent years, hybrid positron emission tomography (PET)/computed tomography (CT) scanners have been increasingly utilized in cardiac applications. PET imaging quality has been improved by the use of new scintillators, small detector element size, and fully 3D iterative reconstruction techniques with time-of-flight information and resolution recovery. Further quality enhancements for cardiac imaging can be obtained by tracking and correcting for cardiac and breathing motion with respiratory gating devices and advanced software techniques. The primary tracers used for PET/CT cardiac imaging are Rubidium-82 (82Rb) and Nitrogen-13-ammonia (13N-ammonia) and 18-F fluorodeoxyglucose used for myocardial viability imaging. A new F-18 perfusion tracer (F-18 Flurpiridaz) is being evaluated. High-resolution multi-slice CT component of the hybrid scanner allows accurate attenuation correction for PET, measurement of CT calcium, and contrast CT angiography. Hybrid PET/CT protocols have demonstrated increased diagnostic accuracy for the detection of obstructive disease compared with standalone techniques. Radiation dose to the patient is a concern in hybrid imaging because multiple scans are performed in one scanning session. 3D PET acquisition combined with the new low-dose CT protocols can reduce the doses significantly. Hybrid PET/CT scanners have also been utilized for anatomically-guided molecular imaging of plaque biology in the carotid vessels, aorta, and coronary vessels. This review summarizes the state-of-the-art hybrid imaging PET/CT instrumentation and advances in the image quality related to cardiac imaging.

Rapid Maxillary Expansion Affects the Spheno-occipital Synchondrosis in Youngsters

To test the null hypothesis that the spheno-occipital synchondrosis does not show bony displacement in response to rapid maxillary expansion (RME) therapy in youngsters. A total of 16 computed tomography (CT) records were taken from 8 growing patients (2 males and 6 females), before (T0) and after (T1) treatment with RME. All patients had been diagnosed originally with transverse maxillary deficiency. The mean chronological age of the patients was 9.8 +/- 1.8 years (range, 8 to 11.4 years). High-resolution multislice multidetector CT was used to study quantitatively the extent of the opening of the spheno-occipital synchondrosis following RME. A low-dose CT scan protocol was used (80 kV, 10 mA) and the data file of each patient was transferred to a workstation where the anteroposterior width of the spheno-occipital synchondrosis was measured on axial images. Before treatment with RME (T0), the anteroposterior mean width of the spheno-occipital synchondrosis was 1.73 +/- 0.46 mm immediately after the active phase of expansion (T1), and the width of the synchondrosis increased to 2.30 +/- 0.47. This difference was statistically significant according to the Wilcoxon signed rank test (P < .05). Rapid maxillary expansion leads to a small immediate widening of the spheno-occipital synchondrosis in youngsters.

Multislice Spiral Computed Tomography for the Evaluation of Stent Patency After Left Main Coronary Artery Stenting

Surveillance conventional coronary angiography (CCA) is recommended 2 to 6 months after stent-supported left main coronary artery (LMCA) percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR), with its attendant risks. Multislice computed tomography (MSCT) is a promising technique for noninvasive coronary evaluation. We evaluated the diagnostic performance of high-resolution MSCT to detect ISR after stenting of the LMCA. Seventy-four patients were prospectively identified from a consecutive patient population scheduled for follow-up CCA after LMCA stenting and underwent MSCT before CCA. Until August 2004, a 16-slice scanner was used (n = 27), but we switched to the 64-slice scanner after that period (n = 43). Patients with initial heart rates > 65 bpm received beta-blockers, which resulted in a mean periscan heart rate of 57 +/- 7 bpm. Among patients with technically adequate scans (n = 70), MSCT correctly identified all patients with ISR (10 of 70) but misclassified 5 patients without ISR (false-positives). Overall, the accuracy of MSCT for detection of angiographic ISR was 93%. The sensitivity, specificity, and positive and negative predictive values were 100%, 91%, 67%, and 100%, respectively. When analysis was restricted to patients with stenting of the LMCA with or without extension into a single major side branch, accuracy was 98%. When both branches of the LMCA bifurcation were stented, accuracy was 83%. For the assessment of stent diameter and area, MSCT showed good correlation with intravascular ultrasound (r = 0.78 and 0.73, respectively). An intravascular ultrasound threshold value > or = 1 mm was identified to reliably detect in-stent neointima hyperplasia with MSCT. Current MSCT technology, in combination with optimal heart rate control, allows reliable noninvasive evaluation of selected patients after LMCA stenting. MSCT is safe to exclude left main ISR and may therefore be an acceptable first-line alternative to CCA.

Endolymphatic Duct Status During Middle Fossa Dissection of the Internal Auditory Canal: A Human Temporal Bone Radiographic Study

Successful hearing preservation after acoustic neuroma resection is sometimes complicated by delayed hearing deterioration. The middle fossa approach appears to offer superior long-term hearing results when compared to the retrosigmoid surgical approach. The goal of this study is to investigate the hypothesis that internal auditory canal (IAC) drilling during middle fossa acoustic neuroma removal is associated with a lower incidence of endolymphatic duct (ELD) injury, a potential cause of delayed hearing loss (HL) known to accompany retrosigmoid hearing preservation dissection techniques. A human temporal bone anatomic and radiographic study complemented with a literature review. Twenty human temporal bones were analyzed with high-resolution multislice computed tomography (HRMCT) and subjected to standard extended middle fossa IAC dissection with labyrinthine preservation and follow-up HRMCT for analyses of the ELD. Zero of 20 (0%) temporal bones were found to have violation of the ELD with preservation of the labyrinthine structures and the endolymphatic sac. Reviews of human and animal studies indicate that injury to the ELD may create endolymphatic hydrops, a known cause of hearing deterioration. The ELD is not vulnerable to injury during IAC dissection using the middle fossa approach. A previous radiographic study has shown that the ELD is violated in 24% of temporal bones during retrosigmoid dissection of the IAC. These findings support and may help explain other outcome studies that show that long-term hearing results are superior with the use of the middle fossa approach when compared to results following retrosigmoid dissection.

Trabecular Bone Structure Obtained From Multislice Spiral Computed Tomography of the Calcaneus Predicts Osteoporotic Vertebral Deformities

To compare multislice computed tomography (MSCT)-derived parameters of the trabecular bone structure of the calcaneus with bone mineral density (BMD) in their ability to differentiate between donors with and without osteoporotic fractures of the spine and to optimize CT scan protocols. Forty-two postmortem calcanei (81.2 +/- 10 years) were imaged with a 16-detector row MSCT system using 4 different scan protocols varying spatial resolution (12-24 lp/cm) and radiation dose. Structural parameters of trabecular bone were derived from these images, and BMDs of the calcanei were determined using dual x-ray absorptiometry. Vertebral deformities of the spine were radiographically classified using the Spinal Fracture Index. Diagnostic performance in differentiation between donors with and without vertebral fractures was assessed using receiver operating characteristic (ROC) analysis. There were significant case-control differences for many of the structural parameters measured (P < 0.05). The highest ROC values were found for apparent trabecular thickness using the high-resolution and high-dose protocols. Statistically significant correlations were found between most structure parameters and BMD (up to r = 0.85, P < 0.01). Structural parameters of trabecular bone as obtained from high-resolution MSCT images of the calcaneus can be used to differentiate between donors with and without osteoporotic vertebral fractures, using a high-resolution and high-dose CT protocol.

Endolymphatic Duct Violation During Retrosigmoid Dissection of the Internal Auditory Canal: A Human Temporal Bone Radiographic Study

Successful hearing preservation after acoustic neuroma resection is sometimes complicated by delayed hearing deterioration. The goal of this study was to investigate the hypothesis that internal auditory canal (IAC) drilling during retrosigmoid acoustic neuroma removal may result in endolymphatic duct (ELD) injury, a potential cause of delayed hearing loss (HL) after hearing preservation surgery. Temporal bone anatomic and radiographic study and literature review. Twenty-one human temporal bones were analyzed with high-resolution multislice computed tomography (HRMCT) and subjected to standard retrosigmoid IAC dissection with labyrinthine preservation and follow-up HRMCT for analyses of the ELD. A MEDLINE search was performed of studies documenting long-term hearing preservation outcomes after retrosigmoid dissection. Five of 21 (24%) bones were found to have violation of the ELD despite preservation of labyrinthine structures and the endolymphatic sac. These results correlate with the mean incidence of long-term hearing decline (26.6%). Reviews of human and animal studies indicate that injury to the ELD may create endolymphatic hydrops. The ELD is vulnerable to injury during IAC dissection even if labyrinthine structures at the lateral aspect of the IAC are preserved. These findings may be helpful in explaining and potentially preventing some cases of long-term hearing deterioration that may be a result of endolymphatic hydrops after ELD injury during acoustic tumor removal. Careful preoperative review of imaging studies using HRMCT may prove useful before retrosigmoid dissection.

Pancreatic carcinoma: the role of high-resolution multislice spiral CT in the diagnosis and assessment of resectability.

The purpose of our study was to evaluate multislice computed tomography (MSCT) in the assessment of patients with clinical, laboratory, and US suspicion of pancreatic neoplasm, and to evaluate resectability status. Forty-six patients with a suspected pancreatic tumor underwent MSCT. After a preliminary precontrast survey, a postcontrast scan was performed in the arterial and portal venous phase with the following protocol: 4 x 1-mm collimation; 1.25- and 5-mm slice thickness width, respectively, and 1- and 5-mm reconstruction interval. In all patients pathological correlation was obtained. The evaluation of all images provided a diagnosis in 44 patients, with a sensitivity, specificity, and accuracy of 97, 80, and 96%, respectively. The MSCT correctly provided a diagnosis of unresectability with sensitivity of 96%, specificity of 86%, and accuracy of 93%. Evaluation of 1-mm slices demonstrated 83 of the 91 liver metastases found at surgery; conversely, the 5-mm slices detected only 76 of these lesions. Infiltration of peripancreatic major vessels was demonstrated, and was confirmed at surgery in 18 patients. High-resolution MSCT improves prediction of resectability in patients with suspected pancreatic carcinoma. Parenchymal and vascular information can be achieved with a single MSCT examination.

Virtual endoscopy of the tympanic cavity based on high-resolution multislice computed tomographic data.

This study was designed to assess the value of high-resolution multislice computed tomography (MSCT) data of the petrous bone for the virtual endoscopic visualization of the tympanic cavity. The recently introduced MSCT technology has improved spatial resolution in the z axis as well as scan speed in computed tomography. Three-dimensional rendering of high-resolution MSCT data of the petrous bone may be expected to provide endoluminal views of superior image quality, thus competing with transtympanic endoscopy (otoendoscopy). This study was conducted at a university teaching hospital. Cadaveric phantom studies in a MSCT scanner were performed to define a data acquisition protocol, combining adequate detail resolution with low tube current. Subsequently, the cadaveric phantom underwent otoendoscopy. The postprocessing parameters of the three-dimensional rendering protocol were chosen to produce views closely resembling the corresponding otoendoscopic images. High-resolution data from 18 patients with pathologic conditions of the middle ear, as suggested by clinical findings and assessment of cross-sectional data, were postprocessed using the volume rendering technique to generate standardized virtual endoscopic views. A total of 36 virtual endoscopic scans of the tympanic cavity were generated. With regard to intermediate and high-density structures, virtual endoscopic images, based on MSCT data, yielded endoluminal views closely resembling corresponding otoendoscopic views. Virtual endoscopy seems useful for imaging ossicular pathologic conditions such as dysplasia and chain disruption as well as for assessing patient status before and after otosurgery. MSCT data sets allow for generating virtual endoscopic views closely resembling otoendoscopic images. The technique is especially useful when ossicular pathologic changes are present as well as for preoperative and postoperative imaging of otologic procedures.