Computed Tomography Workstation Research Articles

Association of computed tomography-derived myocardial mass with fractional flow reserve-verified ischemia or subsequent therapeutic strategy.

The aim of the present study was to examine the association of myocardial mass verified by computed tomography (CT) and invasive fractional flow reserve (FFR)-verified myocardial ischemia, or subsequent therapeutic strategy for the targeted vessels after FFR examination. We examined 333 vessels with intermediate stenoses in 297 patients (mean age 69.0 ± 9.5, 228 men) undergoing both coronary CT angiography and invasive FFR, and reviewed the therapeutic strategy after FFR. Of 333 vessels, FFR ≤ 0.80 was documented in 130 (39.0%). Myocardial volume supplied by the target vessel (MVT) was larger in those with FFR-verified ischemia than those without (53.4 ± 19.5 vs. 42.9 ± 22.2cm3, P < 0.001). Addition of MVT to a model including patient characteristics (age, gender), visual assessment (≥ 70% stenosis, high-risk appearance), and quantitative CT vessel parameters [minimal lumen area (MLA), plaque burden at MLA, percent aggregate plaque volume] improved C-index (from 0.745 to 0.778, P = 0.020). Furthermore, of 130 vessels with FFR ≤ 0.80, myocardial volume exposed to ischemia (MVI) was larger in the vessels with early revascularization after FFR examination than those without (37.2 ± 20.0 vs. 26.8 ± 15.0cm3, P = 0.003), and was independently associated with early revascularization [OR = 1.03, 95% confidence interval (1.02-1.11), P < 0.001]. Using an on-site CT workstation, MVT identified coronary arteries with FFR-verified ischemia easily and non-invasively, and MVI was associated with subsequent therapeutic strategy after FFR examinations.

Evaluation of Bone Mineral Density using Quantitative Computed Tomography in Pre- and Post-menopausal Women: A Retrospective Cross-sectional Study

Introduction: Osteoporosis is increasingly becoming a public health concern especially in the ageing population. Fractures related to osteoporosis are an important cause for pain and disability. Most common methods used for measuring Bone Mineral Density (BMD) include Dual-energy X-ray Absorptiometry (DXA) and Quantitative Computed Tomography (QCT). There is a substantial increase in the number of patients undergoing a primary Computed Tomography (CT) study of the abdomen for various clinical reasons. Use of QCT for measurement of BMD helps to identify the high risk patients for osteoporotic fractures. This also reduces the need for any additional imaging, radiation exposure, cost or patient time. Aim: To compare the BMD values between pre-menopausal and post-menopausal females using QCT. Materials and Methods: This was a retrospective cross- sectional study. A total of 40 patients with 20 patients each in pre- menopausal and post-menopausal group who had undergone routine abdominal CT for various clinical indications unrelated to bone disorders were evaluated. Regions of Interest (ROIs) were measured on the axial images at T12 through L5 vertebrae at three locations, one over the trabecular part of vertebrae, one on the posterior paraspinal muscles and the third ROI over the subcutaneous fat. BMD was calculated by using phantom less QCT software of the Philips CT workstation. Both t-score and BMD values were automatically generated by the software. The thresholds for spinal trabecular BMD were &lt;120 mg/cc for osteopenia (equivalent to a DXA T-score of -1.0 SD) and &lt;80 mg/cc for osteoporosis (equivalent to a DXA T-score of -2.5 SD). Descriptive statistics were used to describe clinical demographics using range, means and Standard Deviation (mean±SD). Student’s t-test was used to analyse comparisons between the study groups. Results: For pre-menopausal women (n=20) in the age group of 30-45 years, the mean BMD observed was 157.01±27.36 mg/cc. For post-menopausal women (n=20) in the age group of &gt;45 years, the mean BMD observed was 129.77±48.92 mg/cc. The mean t-score values for pre-menopausal and post-menopausal women were -0.67±0.88 and -1.57±1.58, respectively. Comparison of t-score (p&lt;0.05) and BMD (p&lt;0.0001) between the two groups was found to be statistically significant. Conclusion: The BMD reduces considerably in the post- menopausal women in comparison to pre-menopausal women. Abdominal CT scans obtained for various clinical indications can be used to identify patients with reduced BMD and helps in early detection of osteoporosis.

Morphometric analysis of foramen magnum using helical computed tomogrophy for gender determination

Background: The morphometric analysis of foramen magnum (FM) plays a crucial role in forensics and paleontology in identifying the gender of the unknown skeletal fragments. However, the reliability of these parameters vary among populations and races. The present study was conducted to investigate the reliability of the four foramen magnum parameters ie, foramen magnum transverse diameter, foramen magnum sagittal diameter, foramen magnum area and foramen magnum circumference in this native population. Methods: A total of 60 subjects belonging to both genders aged between 20 – 50 years who were undergoing computed tomography (CT) examination of head and neck region were selected for the study. The study sample comprised of 30 males in group A and 30 females in group B. The measurements were obtained from reformatted axial sections using helical CT scan. The FM sagittal diameter (FMSD) and the FM transverse diameter (FMTD) were measured by the greatest anteroposterior dimension and the greatest width of the foramen. The circumference (FMC) and the area (FMA) were obtained after tracing the bony margin of the FM on the CT image using CT workstation. Results: Mean values of all four parameters were found to be significantly higher in males compared to female subjects (P &lt;0.001). Further, the accuracy of sex determination analyzed using the discriminant equation was 70% for males and 80% for females with overall accuracy of 75%. The predictability of gender was higher in female subjects than in male subjects. Conclusion: The dimensions of the foramen magnum can be used in gender determination of skeletal fragments with considerable accuracy. The Helical CT scan plays a pivotal role in providing accurate dimensions of the foramen magnum that could be useful in forensic testing.

Diagnosing peripheral lung lesions using endobronchial ultrasonography with guide sheath: A prospective registry study to assess the effect of virtual bronchoscopic navigation using a computed tomography workstation.

Bronchoscopy has a lower diagnostic yield for peripheral lung lesions (PLL). Endobronchial ultrasound guide sheath transbronchial lung biopsy (EBUS GS TBLB) has been used to overcome such limitation. Recent studies revealed that combined methods (e.g., EBUS GS TBLB plus electromagnetic navigation [EMN] or virtual bronchoscopic navigation [VBN]) further improve the diagnostic yield. However, those systems are associated with a high cost burden. Accordingly, we attempted to use VBN by computed tomography (CT) workstation (Aquarius iNtuition, TeraRecon) not dedicated only for VBN as an adjunctive tool for EBUS GS TBLB. We performed a prospective registry study to investigate whether VBN by CT workstation could improve the diagnostic yield of PLL.Between February 2017 and February 2018, 128 patients with PLL were divided into 2 groups (VBN and non-VBN [NVBN]). In NVBN group (n = 64), EBUS GS TBLB was performed using a hand-drawn bronchial map based on CT images. VBN group (n = 64) underwent EBUS GS TBLB using VBN images.VBN using CT workstation did not improve the diagnostic yield of EBUS GS TBLB for PLL (VBN vs NVBN, 72% vs 80%, P = .284). VBN slightly reduced procedure time (minute [mean ± SD], 25.31 ± 10.33 vs 25.81 ± 9.22), navigation time (time to find the lesion) (9.10 ± 7.88 vs 9.50 ± 7.14), and fluoroscopy time (2.23 ± 2.39 vs 2.86 ± 4.61), while these differences were not statistically significant.The diagnostic yield of EBUS GS TBLB was not improved with VBN (compared with using a hand-drawn bronchial map). Although VBN slightly shortened the procedure-related times, which were not significantly different.

The Utility of Virtual Bronchoscopy Using a Computed Tomography Workstation for Conducting Conventional Bronchoscopy: A Retrospective Analysis of Clinical Practice

Background: Recent clinical trials demonstrated the benefits of several guided-bronchoscopy technologies for the diagnosis of peripheral pulmonary lesions (PPLs). However, introduction of these technologies is expensive. Therefore, in clinical practice, these are unavailable in many hospitals. In contrast, virtual bronchoscopy (VB) using the computed tomography (CT) workstation can be made available immediately without additional cost as many hospitals already have the CT scan facility. However, the effectiveness of VB alone remains to be shown. Objectives: The aim of this study was to investigate the effect of VB using the CT workstation in hospitals performing conventional bronchoscopy. Methods: Results from consecutive patients who underwent bronchoscopy for small PPLs (major diameter ≤30 mm) were retrospectively reviewed. Sixty-nine patients who underwent bronchoscopy without VB from April 2014 to March 2015 and 56 patients who underwent bronchoscopy with VB from April 2015 to December 2015 were assigned to non-VB and VB groups, respectively. We compared the two groups and analyzed the factors affecting the diagnostic yield. Results: The VB group had a significantly higher diagnostic yield than the non-VB group (57.1 vs. 33.3%; p = 0.008). In the multivariate analysis, VB was identified as a significant factor affecting the diagnostic yield (odds ratio: 3.30, p = 0.011). Conclusions: In the conventional bronchoscopy settings, VB using the CT workstation is efficient for the diagnosis of PPLs when other guided-bronchoscopy techniques are unavailable.

Thinning of the deep inferior epigastric artery perforator flap based on the vascular structure of the arterial perforator

To explore flap thinning based on the study of the arterial structure and blood perfusion of the deep inferior epigastric artery perforator (DIEP) flap using computed tomography (CT) angiography. Clinical imaging study: Preoperative CT angiography was performed in 15 patients with DIEP flap reconstruction to investigate the vascular structure of arterial perforator. Cadaveric imaging study:10 abdominal specimens harvested from fresh cadavers were cannulated with trocar and injected with contrast medium in the deep inferior epigastric artery perforator. During the perfusion of the contrast medium in the flap,the flap was scanned by three-dimensional CT. The CT data was then sent to CT workstation and the images were processed and reformatted to study the vascular structure of arterial perforators and the blood perfusion. 75 artery perforators in clinical study and 40 artery perforators in cadaveric study were chosen and analyzed. The major deep inferior epigastric artery perforators run directly across the deep layer of adipose tissue without bifurcating beneath the Scarpa's fascia. Above the Scarpa's fascia, the artery perforators bifurcate and ultimately terminate in the subdermal vascular plexus. Blood perfusion mode: The subdermal vascular plexus served as the only pathway for blood perfusion between perforasomes. There are two different pathways for blood perfusion in the perforasome: the subdermal plexus and the existing vascular structure of perforator. Based on the vascular structure of arterial perforator and blood perfusion of the DIEP flap, thinning of the DIEP flap under the Scarpa's fascia is safe while thinning above the Scarpa's fascia should performed according to the blood supply zone of the DIEP flap.

Study of the Impact of the Location of a Perforator in the Perfusion of a Perforator Flap: The Concept of "Angle of Perfusion".

Background Perforator flaps remain challenging in their design, especially as free flaps. We used a cadaveric model to help refine the design of perforator flaps by studying their vascular features. We define the angle of perfusion of a perforator as a tool to achieve safer flap designs. Methods A total of 83 flaps were designed from 20 fresh cadaveric anterolateral thigh flaps. The most dominant perforator larger than 0.5 mm was used as the reference point on the midline of the flap, and the tip of the flap was set at 5 cm (n = 10), 2 cm (n = 5), or 10 cm (n = 5) from this perforator. The perforator was injected with contrast agent, and the flap was scanned with computed tomography (CT) angiography. The vascular territory of the injected perforator was drawn twice by two different investigators. Perfused volumes were then obtained through a computerized algorithm on the CT workstation. Flaps were then flushed with heparinized saline and cut at decreasing angles (120, 90, 60, and 45 degrees) and rescanned with contrast for each perfusion angle. The perfused volumes were calculated for each angle. Results Volume and percentage of perfusion were significantly decreased with decreasing angles of perfusion, regardless of perforator location (2 cm, p = 0.002; 5 cm, p = 0.02; 10 cm, p < 0.001). Conclusions Acute angles of perfusion were associated with fewer incorporated linking vessels and lower flap perfusion. This phenomenon was less apparent in centrally located perforators. Perfusion angle and perforator location influence flap vascularity in a cadaveric model.

Diagnostic utility of endobronchial ultrasound with a guide sheath under the computed tomography workstation (ziostation) for small peripheral pulmonary lesions.

The application of radial probe endobronchial ultrasound (R-EBUS) and virtual bronchoscopic navigation has improved the diagnostic outcome of bronchoscopy for peripheral pulmonary lesions (PPLs). Nonetheless, while existing navigation systems are very useful for selecting the bronchus containing the target lesion, the associated introductory costs are high. Therefore, we focused on virtual bronchoscopy (VB) using the workstation, ziostation that was already available in many countries as an adjunct modality. Consecutive patients who underwent bronchoscopy with R-EBUS for PPLs (major diameter ≤30 mm) were enrolled. From late June 2013 to November 2013, 121 patients were examined with ziostation, and from September 2012 to early June 2013, 113 patients were examined without ziostation. We compared the diagnostic yield, EBUS detection rate and procedure time between two groups to evaluate the utility of the VB. The ziostation group had significantly higher diagnostic yield than the non-ziostation group (77.7% vs 64.6%, P = 0.030). Following the multivariate analysis, use of ziostation was a significant factor affecting the diagnostic yield. Meanwhile, EBUS detection rate was significantly higher in the ziostation group (94.2% vs 75.2%, P < 0.001). And, procedure time was significantly shorter in the ziostation group (mean ± standard deviation: 24.0 ± 7.4 min vs 26.9 ± 7.9 min, P = 0.005). VB offered by the workstation was a valuable tool that facilitated more accurate and rapid bronchoscopy procedure for diagnosis of PPLs.

The super thin external pudendal artery (STEPA) flap

The need for improved microsurgical reconstructive techniques is ongoing given the "ideal" free flap still does not exist. When reconstruction requires a thin flap, options have remained limited and flaps with minimal donor site morbidity that do not require secondary de-bulking have been elusive thus far. The importance of a thin and supple flap cannot be understated when dealing with challenging cases such as the dorsum of the hand or foot. This also applies to other areas such as the head and neck and over the large joints of the knee and elbow. The authors propose a previously un-described free tissue transfer based on the external pudendal artery that fulfills many of the aforementioned goals. An anatomical cadaveric study has been performed describing the super thin external pudendal artery (STEPA) flap. Six fresh cadavers were used in the raising of eight hemiscrotal flaps and two bipedicled scrotal flaps based on the external pudendal vessels. 2 hemipelvises underwent cannulation of the external pudendal artery followed by injection of a barium sulphate/gelatin mixture and three-dimensional computed tomographic angiography to evaluate vascular anatomy. Colored-latex was injected into two raised hemiscrotal flaps. Measurements were made on the cadaveric dissections and on a computed tomography workstation. The average external diameter of the external pudendal artery measured 2.81mm at its origin from the femoral artery, the vein 4.44mm. The mean pedicle length measured 11cm (range, 10-12cm). The mean thickness of the flap measured 1.1mm. A new free flap, the STEPA flap, has been described that is the thinnest myocutaneous free flap with over 80% of the thickness of the flap less than 1.1mm. It has been demonstrated to have reliable anatomy with more than adequate vessel caliber. It has a large surface area and a generous pedicle length for free tissue transfer. Donor site morbidity is favorable. It is accepted that there may be cosmetic issues regarding flap pigmentation and a variable degree of hair in patients where the reconstruction is visible. We would contend that there exist many successful techniques which address pigmentation and depilation, and that this trade-off is acceptable given the functionality and characteristics of this uniquely thin flap. It has the potential to be used in many clinical scenarios where thin supple reconstruction is a high priority.

The Super Thin External Pudendal Artery (STEPA) Flap

INTRODUCTION: The need for improved microsurgical reconstructive techniques is ongoing given the “ideal” free flap still does not exist.1 When reconstruction requires a thin flap, options have remained limited and flaps with minimal donor site morbidity that do not require secondary de-bulking have been elusive thus far. The importance of a thin and supple flap cannot be understated when dealing with challenging cases such as the dorsum of the hand or foot, the head and neck or over joints. The authors propose a previously un-described free tissue transfer based on the external pudendal artery that fulfills many of the aforementioned goals (Figure 1). An anatomical cadaveric study has been performed describing the super thin external pudendal artery (STEPA) flap.Figure 1: Location and pertinent anatomy of the STEPA flap.METHODS: Six fresh cadavers were used in the raising of eight hemiscrotal flaps and two bipedicled scrotal flaps based on the external pudendal vessels. Two unipedicled and both bipedicled flaps underwent cannulation of the external pudendal artery followed by injection of an iodinated contrast medium, iohexol (Omnipaque) and three-dimensional computed tomographic angiography to evaluate vascular anatomy. Colored-latex was injected into one raised hemiscrotal flap. Measurements were made on the cadaveric dissections and on a computed tomography workstation. RESULTS: The average external diameter of the external pudendal artery measured 2.81mm at its origin from the femoral artery, the vein 4.44 mm. The mean pedicle length measured 11cm (range, 10 to 12 cm). The mean thickness of the flap measured 1.1mm. CONCLUSION: A new free flap, the STEPA flap, has been described that is the thinnest myocutaneous free flap with over 80% of the thickness of the flap less than 1.1mm (Figure 2). It has been demonstrated to have reliable anatomy with more than adequate vessel caliber. It has a large surface area and a generous pedicle length for free tissue transfer. Donor site morbidity is favourable. It is accepted that there may be cosmetic issues regarding flap pigmentation and a variable degree of hair in patients where the reconstruction is visible. We contend that there exist many successful techniques which address pigmentation and depilation, and that this trade-off is acceptable given the functionality and characteristics of this uniquely thin flap.2,3 It has the potential to be used in many clinical scenarios where thin supple reconstruction is a high priority.Figure 2: Demonstration of thinnest of the STEPA flap.

Application of four‐dimensional computed tomography angiography in the study of vascular structure of the deep inferior epigastric artery perforator

To explore the vascular structure of the deep inferior epigastric artery perforator with the four‐dimensional computed tomography (CT) angiography. 10 abdominal specimens harvested from fresh cadavers were cannulated with trocar and injected with contrast medium in the deep inferior epigastric artery at different levels. During the perfusion of the contrast medium in the flap, the flap was scanned by three‐dimensional CT (four‐dimensional defined as three dimensional CT plus time). The CT data were sent to CT workstation and the images were processed and reformatted. The deep inferior epigastric artery perforator terminates in the subdermal vascular plexus, with bifurcating superior to the Scarps fascia and under the skin. The anastomosis in the abdominal midline occurs in the subdermal vascular plexus. The zone overlying the rectus muscle in the pedicle side has the best blood supply. The four‐dimensional CT is a useful method to study the vascular structure of the deep inferior epigastric artery perforator in the superficial fascia.Grant Funding Source: Institute of Basic Medical Sciences£¬Chinese Academy of Medical Science Funding(2008PY02)

Computed tomography-based morphometric analysis of cervical pedicles in Indian population

Cervical transpedicular screw fixation is safe and is probably going to be the gold standard for cervical spine fixation. However, cervical transpedicular screw use in the Asian population can be limited as the transverse diameter in this group of patients may not be adequate to accommodate the 3.5-mm pedicular screw thus injuring the vital structures located in the close proximity of the pedicles. Thus lateral mass fixation remains the mainstay of treatment. The present study evaluated the transverse cervical pedicle diameter of C2-C7 vertebrae in a pilot study in 27 Indian subjects using computed tomography (CT) imaging and evaluated the feasibility of transpedicular screw fixation in them. To evaluate the feasibility of transpedicular screw fixation in the Indian population. The cervical pedicle diameter size differs between the Asian and non-Asian population. The authors studied the transverse pedicle diameter of the C2-C7 of the cervical spine in the Indian population using CT measurements. This cross-sectional study was carried out at a tertiary care centre for a period of four months from October 2010 to December 2010. Measurements of cervical pedicles in the subjects were performed on the CT workstation from the CT images taken at 2.5-mm interval. The transverse pedicle diameter was defined as the outermost diameter of the pedicle, taken perpendicular to the axis of the pedicle at the narrowest point and measured in millimeters±0.1 mm. Descriptive statistics was used to represent percentage of transverse diameter of cervical pedicles less than 5 mm in male and female subjects at C2-C7 levels. Since there is no previous study done in India, we initiated the study with sample size of 27 as a pilot study. The statistical analysis was performed using SPSS software. The mean transverse diameters of the cervical pedicles of C2, C3, C4, C5, C6 and C7 in males were 5.3, 5.3, 5.3, 5.6, 5.6 and 6.1 mm respectively and ranged between 5.3 to 6.1 mm. The mean transverse diameters of the cervical pedicles of C2, C3, C4, C5, C6 and C7 in females were 5.1, 4.6, 4.7, 4.7, 5.3 and 5.6 mm respectively and ranged between 4.6 to 5.6 mm. Between 2.1% and 55.7% of pedicles in our male population and between 5.5% and 74.3% pedicles in our female population was smaller than 5.0 mm in transverse diameter and thus cannot have fixation with a 3.5 mm screw using this technique. We found that the transverse pedicle diameter of cervical pedicles in the Indian subjects is smaller compared to the Western population. Although transpedicular screw fixation has stronger pullout strength compared to lateral mass fixation, its use must be considered carefully and individually. Preoperative CT evaluation is a must before transpedicular fixation in the cervical spine, especially in the Indian female population. As an option 2.7-mm screws can be devised for the Indian population giving a wider safety margin.

Anatomic and radiological study on posterior pedicle screw fixation in the atlantoaxial vertebrae of children

Objective To investigate the feasibility of posterior fixation with 3.5-mm pedicle screws in the atlantoaxial vertebrae of children. Methods In this study, atlantoaxial vertebrae specimens were obtained from 10 cadavers of children aged 6–8 years. We measured the height and width of the C 1 pedicle and the midportion of C 1 lateral mass; the width of C 1 posterior arch under the vertebral artery groove and the height of the external and internal one-third of this part; the external, internal height and the superior, middle, inferior width of the C 2 pedicle (transverse foramen). Furthermore, computed tomography (CT) axial scan was performed on 20 age-matched volunteers to obtain relative data of their atlanto-axial vertebrae. We measured the length and width of the C 1 and C 2 pedicles in the atlantoaxial cross-sectional plane. On CT workstation, we also measured the angles between the longitudinal axes of the atlantoaxial pedicles and the mid-sagittal plane. Results For the cadaveric specimen group, the height and width of the C 1 pedicle were (5.26±0.44) mm and (6.26± 0.75) mm respectively. The height of the medial one-third of the C 1 posterior arch under the vertebral artery groove was (4.07±0.24) mm. The external, internal height and superior, middle, inferior width of the C 2 pedicle was (6.86±0.48) mm, (6.67±0.49) mm, (6.63 ±0.61) mm, (5.41± 0.39) mm and (3. 71 ±0.30) mm, respectively. For the volunteer group measured by CT scan, the height and width of the C 1 pedicle were (5.47 ±0.34) mm and (6.63±0.54) mm respectively, while (6.59± 0.51) mm and (5.13 ±0.42) mm of the C 2 pedic le. The angles between the atlas, axis pedicles and the midsagittal plane were (9.60±1.32)° and (27.80±2.22)° respectively . Conclusion It is feasible to place a 3.5-mm pedicle screw in the C 1 and C 2 pedicles of children aged 6–8 years old.

Application of four-dimensional computed tomography angiography in the study of vascular structure of the deep inferior epigastric artery perforator

To explore the vascular structure of the deep inferior epigastric artery perforator with the four-dimensional computed tomography (CT) angiography. 10 abdominal specimens harvested from fresh cadavers were cannulated with trocar and injected with contrast medium in the deep inferior epigastric artery at different levels, including the deep inferior epigastric artery, its bifurcations, the lateral or medial large perforators. During the perfusion of the contrast medium in the flap, the flap was scanned by three-dimensional CT (four-dimensional defined as three dimensional CT plus time). The CT data were sent to CT workstation and the images were processed and reformatted. The deep inferior epigastric artery perforator terminates in the subdermal vascular plexus, with bifurcating superior to the Scarpa fascia and under the skin. The anastomosis in the abdominal midline occurs in the subdermal vascular plexus. The blood flow distributes in two ways, one is the subdermal vascular plexus, the other is the existed vascular structure. The zone overlying the rectus muscle in the pedicle side has the best blood supply, the other adjacent zone on the ipsilateral side of the abdomen, the zone overlying the contralateral rectus muscle and the zone lateral to the contralateral rectus muscle has declining perfusion. The four-dimensional CT is a useful method to study the vascular structure of the deep inferior epigastric artery perforator in the superficial fascia.

Computed tomography measurement of tophus volume: Comparison with physical measurement

Computed tomography (CT) has high accuracy for tophus detection. This study assessed reliability of CT measurement of tophus volume and compared reproducibility of CT with physical measurement of tophus size. Forty-seven hand tophi were analyzed in 20 patients with gout. The longest tophus diameter was recorded by 2 independent observers. All patients proceeded to CT scanning of the hands on a Philips Brilliance scanner (0.8-mm slices). Two independent observers measured tophus volume using the Surface Shaded Display 3-dimensional function on the Philips CT workstation. Five patients underwent repeat physical and CT assessments within 1 week (18 observations). Inter- and intraobserver reproducibility were analyzed by limits of agreement and coefficients of variation. Of the 47 lesions identified as tophi on physical examination, 42 (89%) were also identified on CT. The mean (95% confidence interval [95% CI]) difference between observers for physical measurement was 0.45 mm (-4.07, 4.96) and for CT was 65.2 mm(3) (-293.0, 423.3). The mean (95% CI) difference between visits for physical measurement was -0.72 mm (-5.47, 4.03) and for CT was -13.1 mm(3) (-112.5, 86.3). There was no difference between coefficients of variation for inter- and intraobserver reproducibility for the 2 measurement techniques. For tophi identified by physical and CT assessment, there was good correlation between measurements (r = 0.91, P < 0.0001). CT assessment of tophus volume is reliable and reproducible. However, physical measurement correlates well with CT and has equivalent reproducibility. These data support the use of physical measurement as a simple and reliable method to assess tophus size.

Direct Anatomical Localization of the Subthalamic Nucleus on CT with Comparison to Schaltenbrand-Wahren Atlas

Stimulation of the subthalamic nucleus (STN) has become an accepted treatment for motor symptoms of Parkinson’s disease. Generally, localization of the target is based on stereotactic atlas coordinates and magnetic resonance (MR) images. In this paper a method of direct anatomical localization of the STN on computed tomography (CT) images is described and compared with the Schaltenbrand-Wahren atlas. Serial CT scans were obtained at 1.5-mm interval and scan thickness of 3 mm, with the CT gantry and glabella-inion plane of the patient’s head vertical. The STN was identified as a dense structure medial to the inner semicircular border of the internal capsule in the subthalamic region. Its visibility was increased by changing the window and level settings on the CT workstation computer. The center of the STN in relationship to the intercommissural line, determined by this technique, was similar to those found on standard atlases.

Eye movement during computed tomography interpretation: Eyetracker results and image display-time implications

Stacked displays hold the potential for accurate interpretation of multiple computed tomography (CT) studies on a low-cost workstation. But can such a display scroll as quickly as radiologists can move their eyes to the next image on a film? To address this question, eye-movement duration during CT chest interpretation was recorded using an electronic eye tracker. Adjacent eye movements (+/- 1 image in sequence) averaged 0.54 seconds. Time motion analysis indicates that a CT workstation using a stacked approach with a 0.2-second image display time and a simple interaction can display the next image in less than 0.4 seconds, so a stacked approach should allow a low-cost workstation to facilitate acceptable interpretation of multiple CT or magnetic resonance studies. However, nonadjacent eye movements is likely to take longer and radiologist behavior may be effected.