3D Shaded Surface Display Research Articles

3D‐CT Comparison of the Stylohyoid Chain in Eagle's Syndromes, Glossopharyngeal Neuralgia, and Asymptomatic Controls

Objectives: (1) Describe 3-dimensional (3D) computed tomography (CT) anatomic features of the stylohyoid chain in Eagle’s syndrome patients (ES), glossopharyngeal neuralgia patients (GPN), and normal asymptomatic controls (NC). (2) Understand 3D-CT features findings associated with Eagle’s syndrome. Methods: Retrospective chart review from November 2000 to November 2013. 3D shaded surface display CT reconstructions of the stylohyoid chain were generated for 10 ES patients, 16 GPN, and 15 NC patients. Demographic and clinical symptom data were recorded. Anatomic data collected from CT scans included: length of ossified styloid process, anterior-posterior (APA) and medial-lateral (MLA) styloid process angulation, ossification pattern of the stylohyoid chain, and minimum distances between the styloid process and the internal carotid artery, C1 transverse process, and tonsillar fossa. Results: The average distance from the styloid process tip to the tonsillar fossa was found to be significantly shorter in ES patients (12.7 mm) compared with GPN (21.4 mm; P < .05) or NC (24.8 mm; P < .001) patients. No other measured variables were found to be significantly different between groups, including average styloid process length (ES: 48.0 vs GPN: 40.3 vs NC: 40 mm; P > .05). Conclusions: The styloid process was found to be significantly closer to the tonsillar fossa in ES patients as compared to GPN and NC patients by 3D-CT reconstructions. No significant differences were found in other measures, including styloid process length. Distance to the tonsillar fossa may be a more appropriate diagnostic criterion for ES than styloid process length, and may contribute to the pathophysiology of ES.

Follow-Up of Coiled Cerebral Aneurysms at 3T: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography

Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms. Fifty-two patients treated with Guglielmi detachable coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence. In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly (P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up. At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts.

Image-guided virtual autopsy findings of gunshot victims performed with multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) and subsequent correlation between radiology and autopsy findings

Because the use of radiology in modern forensic medicine has been, until today, mostly restricted to conventional X-rays, which reduces a 3D body to a 2D projection, a detailed 3D documentation of a gunshot’s wound ballistic effects was not possible. The aim of our study was to evaluate whether the progress in imaging techniques over the last years has made it possible to establish an observer-independent and reproducible forensic assessment using multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) technologies for the documentation and analysis of gunshot wounds. The bodies of eight gunshot victims were scanned by MSCT and by MRI; the data of these imaging techniques were post-processed on a workstation, interpreted and subsequently correlated with the findings of classical autopsy. With the spiral CT and MRI examinations and the subsequent 2D multi-planar reformation (MPR) and 3D shaded surface display (SSD) reconstruction, the entire gunshot-created complex skull fractures and brain injuries (such as wound channels and deeply-driven bone splinters) could be documented in complete and graphic detail. CT and MRI also documented vital reaction to the gunshot by demonstrating air emboli in the heart and blood vessels and the classic pattern of blood aspiration to the lung. Gunshot residues deposited within and under the skin were visible. In conclusion, we think that the radiological methods of MSCT and MRI have the potential to become a routine “virtual autopsy” tool in the future. Bullets and relevant histological samples from specific sites then might be won in image-guided minimally invasive fashion via percutaneous biopsy. The rapid application of developing radiological methods may lead to new horizons in forensic documentation and intravital as well as postmortem examination.

Obliquely oriented superior accessory fissure of the lower lobe of the lung: CT evaluation of the normal appearance and effect on the distribution of parenchymal and pleural opacities.

To review computed tomographic (CT) and radiographic features of an oblique superior accessory fissure in the lower lobe of the lung. CT scans in 34 patients with a prospectively identified accessory fissure of the lower lobe were reviewed and correlated with chest radiographs (31 patients). The fissure and its relationship to segmental bronchovascular structures were evaluated on transverse scans. Three-dimensional (3D) shaded surface display (SSD) reconstructions were obtained from spiral volume data (six patients). Thirty-four patients had 36 accessory fissures (26 right, 10 left). Four of the 36 accessory fissures were manifested by a normal fissure line; two, by slight thickening or minimal linear atelectasis; 16, by thicker linear or subsegmental atelectasis; two, by contiguous tumor infiltration; one, by adjacent consolidation; and 11, by intrafissural extension of pleural fluid. Analysis of bronchovascular structures revealed that this fissure was the superior accessory fissure. The 3D SSD reconstructions demonstrated an oblique orientation. On frontal radiographs, presence of this fissure correlated with a curvilinear band of atelectasis coursing inferomedially and obliquely from its intersection with the lateral aspect of the major fissure toward the infrahilar region on the right and the heart border on the left. Chest radiographs also showed intrafissural extension of pleural fluid. A superior accessory fissure of the lower lobe, more common on the right than on the left, can be identified at transverse CT. Contrary to previous descriptions, it may be oblique, as findings on transverse images suggest and 3D SSD reconstructions confirm. Its presence correlates with characteristic patterns of atelectasis and pleural fluid collection on conventional radiographs.

Causes and corrections for 3D image artifact in HCT

In recent years, helical computed tomography (HCT) has gained significant popularity in clinical applications. The advantages of HCT include the capability of scanning a complete anatomical volume in a single breath-hold and the capability of generating images at arbitrary locations. Because of the inherent inconsistency in the helical data set, however, recent studies have unveiled various HCT-related image artifacts. In this paper, we have performed a detailed analysis on one of the artifacts in the 3D shaded surface display (SSD): the artifact. We have developed an analytical model to show that the artifact is caused by the angular-dependent edge response of the HCT reconstruction algorithm. The accuracy of the model is confirmed by both computer simulations and phantom experiments. Based on the model, we have presented several correction algorithms to combat the grooving artifacts. Computer simulations and phantom experiments are used to demonstrate the effectiveness and robustness of the corrections.

Accessory cardiac bronchus: 3D CT demonstration in nine cases.

Accessory cardiac bronchus (ACB) has been described mainly as isolated case reports in the literature. We report nine consecutive cases of ACB, which occurred in five males and four females and were detected in 11,159 routine spiral CT examinations of the chest, performed between 1994 and 1998. Frequency of the anomaly was 0.08 %. Accessory cardiac bronchus originated from the intermediate bronchus in eight cases and from the right main bronchus in one case. Mean largest diameter of ACB was 8.7 mm (range 4.0-13.8 mm) and mean length was 11.9 mm (range 4.2-23.4 mm). An abnormal pulmonary artery was observed in one case. Six bronchi presented with a blind distal extremity and three showed a ventilated lobulus with a mean largest diameter of 37.5 mm (range 18.6-62.0 mm). All ACBs were documented by 3D shaded-surface display (SSD) and virtual endobronchial navigation, which may facilitate the diagnosis. The literature was reviewed.

Multiplanar and 3D CT of acetabular fractures.

To establish a standard protocol for the multiplanar (MPR) and 3D shaded surface display (SSD) reconstruction of CT data on acetabular fractures, and to assess the usefulness of these reformats. Acetabular fractures in 15 patients were imaged by means of plain radiographs, transaxial CT, MPR reformats, and SSD reformats. The classification of the acetabular fracture was revised in 7/15 cases when the transaxial CT images were read after the plain radiographs. Although the MPR and SSD reformats did not alter the classification, they did add to the degree of confidence in the diagnosis in 9/15 cases. In 2 patients, the MPR and SSD reformats indicated operative instead of conservative treatment. In the MPR reformats, the following views were considered essential in all cases: (a) along the anterior column; (b) along the posterior column; and (c) along both columns and the inferior ramus. In the SSD reformats, the following views were considered essential in all cases: (d) the latero-caudal en face view into the acetabulum; and 180 degrees opposite to this, (e) the medio-cranial view (facing the quadrilateral plate). In 10/15 cases, these views were all that was needed for classification. It was, however, essential to remove the femur from the images before reconstructing the SSD views. Complex acetabular fractures with displacement should be evaluated by means of transaxial CT and additional MPR and SSD reformats. The use of appropriate standard MPR and SSD views shortens the time required to produce the reformats and thereby maximizes the benefit gained.

Multiplanar and three-dimensional reconstruction techniques in CT: impact on chest diseases

The purpose of this review is to capture the current state-of-the art of the technical aspects of multiplanar and three-dimensional (3D) images and their thoracic applications. Planimetric and volumetric analysis resulting from volumetric data acquisitions obviates the limitations of segmented transverse images. Among the 3D reconstruction techniques currently available, the most recently introduced technique, i. e., volume rendering, has to be evaluated in comparison with 3D shaded surface display and maximum or minimum intensity projection. Slabs are useful in detecting and localizing micronodular or microtubular patterns and in analyzing mild forms of uneven attenuation of the lungs. Three-dimensional angiography is helpful in the pretherapeutic evaluation and posttreatment follow-up of pulmonary arteriovenous malformations, in the comprehension of the postoperative reorientation of the pulmonary vessels, in the surgical planning of pulmonary tumors, and in the diagnosis of marginated thrombi. The systemic supply to the lung and superior vena cava syndromes are also relevant to these techniques. In acquired or congenital tracheobronchial diseases including stenosis, extraluminal air and complex airway anatomy, multiplanar and 3D reformations have a complementary role to both transaxial images and endoscopy. New developments are also expected in various topics such as 3D conformal radiation therapy, planning of intraluminal bronchoscopic therapy, virtual endoscopy, and functional imaging of the bronchial tree. Miscellaneous clinical applications are promising in the analysis of diaphragmatic morphology and pathophysiology, in the volumetric quantification of the lung parenchyma, and in the vascular components of the thoracic outlet syndromes.