Volume-rendered Reconstruction Research Articles

Preoperative evaluation of a subungual glomus tumor case using multidetector computed tomography angiography.

Dear Editor: Glomus tumors (GTs) are characterized by the triad of severe pain, pinpoint tenderness, and cold sensitivity. Most GTs are located in the fingertips, especially in the subungual region1,2. Ultrasonography and magnetic resonance imaging (MRI) are useful for preoperative diagnosis, and complete excision is usually recommended1,2,3,4,5. Although it is feasible to use multidetector computed tomography (MDCT) in the diagnosis of suspected vascular diseases, it has been not applied in subungual GT. Here, we describe a patient with a subungual GT that was identified using MDCT angiography. This study is approved by Affiliated Hospital of Guangdong Medical College (IRB No. PJ2012131). A 23-year-old woman presented with a 2-year history of severe pain in the thumb of the right hand on touch or exposure to cold. Physical examination revealed a 6×4-mm, purplish, flush with distal yellowish discoloration on the proximal nail plate of the right thumb (Fig. 1A). Palpation of the nail yielded excruciating pain. The patient was otherwise healthy and routine laboratory results were unremarkable. Ultrasonography revealed a 5.1×2.2-mm, hypervascular, hypoechogenic mass in the proximal nail bed of the right thumb. Fig. 1 Subungual glomus tumor on the distal part of the right thumb. (A) A 6×4-mm purplish flush (arrow) with distal yellowish discoloration on the right thumb. (B) No nail abnormality present at 4 months postoperation. The patient underwent 64-MDCT (Siemens Healthcare, Erlangen, Germany), and three-dimensional volume-rendered images were acquired on a workstation using 0.6-mm slice thickness and 0.4-mm interval. The scanned area ranged from the fingertips to the distal parts of the metacarpal bones of the right thumb. The contrast-enhanced scan was performed after pre-contrast scanning; image acquisition was begun after a delay of 30 s. The enhanced scanning showed a subungual nodule on the radial side of the right thumb and a depression of the distal phalanx. Volume-rendered reconstruction of bone images revealed a local depression in the distal phalanx of the right thumb, while vascular reconstruction enabled the visualization of a 4.5×3.5-mm subungual mass (Fig. 2) Fig. 2 Volume-rendered image of the vascular reconstruction displaying a hypervascularized nodule (arrow) overlying the distal phalanx of the right thumb. The patient underwent a transungual tumor resection with nail plate avulsion. A poorly demarcated reddish nodule was excised en bloc, followed by radiofrequency destruction. The nail bed wound healed through secondary wound closure. Pathological examination showed numerous small blood vessels surrounded by clusters of uniform cells. The cells were round with faintly eosinophilic cytoplasm and round nuclei. CD34 immunoreactivity was detected in both tumor and vascular endothelial cells, while α-smooth muscle actin was detected in the tumor cells. A diagnosis of subungual GT was made based on clinicopathologic clinicopathologic and immunohistochemical results. The patient had no nail abnormality at the 6-month follow-up (Fig. 1B). Since GT tumors are often only a few millimeters in size and the resection area is small, the surgical management of subungual GTs is challenging3. Ultrasound and MRI can display GTs as small as 2 mm in diameter1,4, but they are unable to achieve satisfactory bone imaging. Furthermore, it is difficult to display small and flattened subungual lesions with ultrasonography because the imaging results are often operator-dependent and the nail plate curvature may contribute to artifacts in the lateral nail folds4. In the presented case, repetitive ultrasonography showed a poorly demarcated hypoechogenic nodule, while MDCT angiography delineated a well-defined mass overlying a depression of the distal phalanx. Three-dimensional reconstruction can illustrate the tumor, vascular branches, and bony components in a single image. Therefore, although composite images of photography and ultrasonography can often identify the location and extent of subungual GTs5, MDCT angiography may be a more promising technique for an ill-defined tumor. In all, 5%~50% of postoperative recurrences are due to incomplete surgical removal of the tumor4. Because the tumor in the current case had ill-defined margins and a deep location, subsequent radiofrequency destruction was employed to prevent a possible recurrence.

Four-dimensional computed tomography scans facilitate preoperative planning in snapping scapula syndrome

Because a 4-dimensional CT scan (4D CT) is able to provide a moving 3-dimensional (3D) image in real time in patients with snapping scapula syndrome, a 4D CT scan should be able to demonstrate bony impingement of the scapula on the posterior thorax. This study was performed to determine if 4D CT scans aid the clinician in defining the size and location of the scapular bone causing impingement in patients with snapping scapula syndrome. Between October 2009 and August 2013, 12 patients (median age, 26.5 years; range 15-55 years) with snapping scapula syndrome were investigated with 4D CT. The images formed produced a dynamic volume-rendered reconstruction of the scapulothoracic joint that displayed its movements and any dynamic area of impingement of the scapula on surrounding bony structures. Asymmetry between symptomatic and asymptomatic scapulae was used to determine the radiologic cause of the patient's symptoms. After the failure of conservative management, 8 patients underwent surgery for their condition. Five patients demonstrated bony contact of the scapula on the posterior thoracic ribs. Four patients demonstrated no bony contact but close apposition of the scapula to the posterior thoracic ribs. Three patients demonstrated no bony impingement but abnormal movement of the second and third rib caused by a soft-tissue tethering structure. The 4D CT scan images defined pathology well in patients with snapping scapula syndrome and improved assessment of the amount and location of the scapular bone and soft tissue causing symptoms.

Preaortic iliac vein and double inferior vena cava.

A 64-year-old man was admitted to our hospital for surgery of an abdominal aortic aneurysm (AAA). Computed tomography showed the AAA, both common iliac arterial aneurysms, and anomalies of the retroperitoneal venous system. Three-dimensional volume-rendered reconstruction clearly demonstrated the preaortic iliac veins and the double inferior vena cava (A/Cover). The left common iliac vein (CIV) crossed over the right common iliac artery (CIA) and the right CIV was also located anterior to the right CIA. Both CIVs were parallel to the right side of the abdominal aorta, as the double inferior vena cava. The confluent position of both CIVs was superior to the right renal artery and, thereafter, the common inferior vena cava was formed. In addition, the left renal vein was positioned behind the abdominal aorta. The AAA was replaced by open surgery with a quadrifurcated prosthesis. The right limbs of the graft tunneled through the former the right CIA and were placed behind the right CIV (B). Postoperative computed tomography showed that all four branches of the graft were patent, and the venous drainage was satisfactory (C). The patient was discharged 10 days after the surgery without complications. The patient has consented to publication.

Correction: Corrigendum: Mitofusin 2 tethers endoplasmic reticulum to mitochondria

Nature 456, 605–610 (2008); doi:10.1038/nature07534 In Fig. 1a of this Article, the representative image of a volume-rendered three-dimensional reconstruction of a z-stack of confocal images of endoplasmic-reticulum-targeted yellow fluorescent protein (ER-YFP) in a Mfn2−/− cell expressing MFN2IYFFT and that of a Mfn1−/− cell appear to be duplicated.

An alternative contrast medium for computed tomographic angiography: gadolinium.

Sir: Computed tomography is the mainstay for perforator flap angiographic mapping. There is an increasing foundation of evidence in the literature for the use of computed tomographic angiography in the planning of free flaps, able to guide the surgical approach and improve operative outcomes. Iodinated contrast is the gold standard contrast medium for angiographic imaging. Used in either an oil- or water-soluble form, the radiopaque medium is administered intravenously to improve visibility of the vasculature on radiographic images. However, iodinated contrasts are associated with nephrotoxicity and are strongly contraindicated in patients with poor renal function.1 Magnetic resonance angiography has been suggested for use in such a scenario, when iodinated contrast media are not suitable. However, magnetic resonance angiography is also contraindicated in some settings, particularly where there are implanted metallic devices (such as some breast implants). In these cases, options for high-resolution preoperative imaging are limited. We describe the use of gadolinium as an alternative to iodinated contrast media for use in computed tomographic angiography for preoperative flap imaging. This enables the use of the gold standard modality in patients that otherwise would be unable to undergo imaging with computed tomography. Although this has not been described before, gadolinium has been tested as a contrast medium in computed tomography previously.2,3 Gadolinium, with an atomic number of 64, is a rare earth metal that, because of its paramagnetic properties, is an extremely efficacious contrast agent. In its chelated form, gadolinium has been shown to be considerably less nephrotoxic and allergenic than iodinated contrast compounds1 and is not associated, as previously thought, with any increased risk of the development of nephrogenic systemic fibrosis.4 The use of gadolinium (gadolinium diethylenetriaminepentaacetic acid)-enhanced computed tomographic angiography has been described in aortography and other large vessel angiography. The results have been verified with other forms of imaging and the conclusions have been predominantly positive. Chryssidis et al. describe the use of gadolinium for thoracic aortic aneurysm diagnosis, with vascular enhancement concluded to be sufficient for the confident exclusion of an intimal flap with confirmation of findings by magnetic resonance imaging.5 These findings are consistent across thoracic, abdominal, and cerebral vessel imaging. We have used this imaging in two patients who both required vascular mapping for preoperative flap planning, and who were both unable, for various indications, to receive either iodinated contrast or undergo magnetic resonance imaging. The images below are from a woman presenting for unilateral breast reconstruction, for whom iodinated contrast was contraindicated because of impaired renal function and for whom magnetic resonance imaging was also contraindicated because of her breast expander in situ (Mentor 550 cc Tall height model 354/6313; Mentor Corp., Santa Barbara, Calif.), which is incompatible with magnetic resonance imaging because of a magnetic port. Figures 1 and 2 clearly demonstrate the right lateral thoracic and thoracodorsal arteries, imaged for use in a breast-sharing procedure.Fig. 1: Computed tomographic angiogram, maximum-intensity projection software reconstruction, with gadolinium contrast medium, highlighting opacification of the lateral thoracic artery (blue arrow) and thoracodorsal artery (red arrow).Fig. 2: Computed tomographic angiogram, three-dimensional volume-rendered technique software reconstruction, with gadolinium contrast medium, highlighting opacification of the lateral thoracic artery (blue arrow).In both cases, accurate and relevant angiographic data were gained. Despite these being the first two scans of this type obtained, the contrast injections were able to be timed effectively and gadolinium was shown to be a valuable contrast agent when other forms of scanning are contraindicated. DISCLOSURE The authors declare that there is no source of financial or other support or any financial or professional relationship that might pose a competing interest. There was no source of funding for this article. Phaethon Karagiannis, M.B.B.S. Vachara Niumsawatt, M.B.B.S. Department of Surgery Monash University Monash Medical Centre Clayton, Victoria, Australia Warren M. Rozen, M.B.B.S., M.D., Ph.D. Department of Surgery Monash University Monash Medical Centre Clayton, Victoria, and Department of Surgery School of Medicine and Dentistry James Cook University Clinical School Townsville, Queensland, Australia [email protected]

Stapes Crural Fracture without Perilymph Fistula by Q-Tip Injury

We report a rare case where Q-tip induced mixed hearing loss without perilymph fistula and demonstrate the need for computed tomography imaging with three-dimensional reconstruction where fracture and dislocation of the stapes are suspected. A 28-year-old male experienced an accidental penetrating injury by a Q-tip in the right ear 6 years previously. Temporal bone computed tomography revealed a dislocation of the stapes and incus. A volume-rendered three-dimensional reconstruction revealed that the stapes was rotated 180° laterally toward the handle of the malleus. Exploratory tympanotomy revealed dislocation of the incus and superstructure of the stapes, with an intact tympanic membrane. The patient’s hearing was successfully improved by ossiculoplasty (malleus-footplate assembly) using autologous incus. To differentiate stapes fracture with dislocation as the cause of traumatic conductive hearing loss, three-dimensional reconstruction of the temporal bone computed tomography is helpful before exploratory tympanotomy.

Acute aortic dissection in an adult patient with retro-oesophageal aortic arch

Figure 2: (A, anterior view) Volume-rendering reconstruction from computed tomography scan revealed that the following branches were arising from the abnormal aortic arch: left common carotid artery, right common carotid artery, right subclavian artery and left subclavian artery. The left common carotid artery contributed to the partial vascular ring; however, there were no symptoms of trachea-oesophageal compression in this patient. (B: posterior view) clearly showing the extension of the dissection of the aortic arch.

Aneurysm of a Saphenous Vein Aortocoronary Graft

A 79-year-old male who underwent coronary artery bypass graft surgery (free LIMA, two vein grafts) in 1990 was admitted with exertional dyspnea. A chest computed tomography (CT) revealed a solid lingular mass (Fig. 1), which, on CT-guided biopsy, was shown to be an adenocarcinoma. In addition, there was a large bilobed, partially thrombosed aneurysm of the obtuse marginal vein graft (Fig. 2). A 3D volume-rendered reconstruction showed a 5.8 cm 6.2 cm superior lobe and a 8.7 cm 6.6 cm inferior lobe aneurysm (Fig. 3). Following a diagnostic mediastinoscopy, he developed pulmonary edema and persistent hypoxemia, and therefore surgical correction of the aneurysm was not pursued.

Comparison of Alternative Image Reformatting Techniques in Micro–Computed Tomography and Tooth Clearing for Detailed Canal Morphology

IntroductionMicro–computed tomography (MCT) shows detailed root canal morphology that is not seen with traditional tooth clearing. However, alternative image reformatting techniques in MCT involving 2-dimensional (2D) minimum intensity projection (MinIP) and 3-dimensional (3D) volume-rendering reconstruction have not been directly compared with clearing. The aim was to compare alternative image reformatting techniques in MCT with tooth clearing on the mesiobuccal (MB) root of maxillary first molars. MethodsEighteen maxillary first molar MB roots were scanned, and 2D MinIP and 3D volume-rendered images were reconstructed. Subsequently, the same MB roots were processed by traditional tooth clearing. Images from 2D, 3D, 2D + 3D, and clearing techniques were assessed by 4 endodontists to classify canal configuration and to identify fine anatomic structures such as accessory canals, intercanal communications, and loops. ResultsAll image reformatting techniques in MCT showed detailed configurations and numerous fine structures, such that none were classified as simple type I or II canals; several were classified as types III and IV according to Weine classification or types IV, V, and VI according to Vertucci; and most were nonclassifiable because of their complexity. The clearing images showed less detail, few fine structures, and numerous type I canals. Classification of canal configuration was in 100% intraobserver agreement for all 18 roots visualized by any of the image reformatting techniques in MCT but for only 4 roots (22.2%) classified according to Weine and 6 (33.3%) classified according to Vertucci, when using the clearing technique. ConclusionsThe combination of 2D MinIP and 3D volume-rendered images showed the most detailed canal morphology and fine anatomic structures.

Mri-guided approach to localize and ablate gaps in repeated atrial fibrillation ablation procedure

Introduction: Recurrences of atrial fibrillation (AF) after pulmonary vein (PV) isolation may be related to gaps at the ablation lines. Delayed-enhanced cardiac magnetic resonance (DE-CMR) allows the identification of radiofrequency (RF) lesions and gaps (CMR gaps). The present study aimed to test the usefulness of a new DE-CMR guided approach to ablate gaps in re-do procedures. Methods: Using DE-CMR, a 3D volume-rendered left atrial reconstruction (3D model) was created, after manually segmenting endocardium and epicardium. A pixel signal intensity map was projected on the 3D model and color-coded. The 3D model was imported into the navigation system. RF was delivered targeting the CMR gaps, with the operator blinded to electrical data. Results: Twelve patients were analyzed (58±8 years, 7 with paroxysmal AF, median [IQR] time from prior PV isolation of 16.5 [9-25.5] months). Four patients had additional roof-line ablation. In total, 68 CMR gaps were identified around the PVs and 13 at the roof-line, with a mean of 6.8 gaps/patient and median length of 5.5 mm/gap. Of 43 PVs 38 were electrically reconnected (median of 3 PV/patient). All reconnected PVs presented CMR gaps, with functional electrical-CMR concordance of 88.9%. Guided by the 3D model, isolation of 95% of PVs and conduction block through the roof-line was achieved after a mean of 3.7±3.4 RF applications/gap (22.0±20.2/patient) and 2.8±2.2 min/gap (29.3±14.0 min/patient). Conclusion: DE-CMR is a useful tool to guide the repeat PV isolation procedure by accurately identifying and locating the gaps, with the potential of reducing procedure duration and RF application time.

A unique pulmonary vascular pattern: bilateral anomalous single pulmonary veins

A 56-year-old woman underwent chest x-ray for evaluation of a pelvic tumour. The x-ray showed a unique pattern of bilateral, anomalous, curvilinear vessels (figure 1A). CT with volume-rendered reconstruction (figure...

La classification histopathologique simplifiée des tumeurs présentée à l’aide d’un outil pédagogique collaboratif en ligne en mode zoom

To evaluate feasibility and image quality of time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium–pulmonary veins (LA–PV) complex with half dose of intravenous gadolinium-based contrast agent (GBCA) in patients candidate to percutaneous radiofrequency ablation of atrial fibrillation.Fifty-seven patients underwent CEMRA of the LA–PV complex on a 1.5 T MRI scanner. On 24/57 patients, a conventional fast-spoiled gradient-echo (FSPGR) CEMRA acquisition was run using 0.2 mL/kg of 0.5 M GBCA at 2 mL/s flow rate (protocol A), while in 33/57 patients a time-resolved multiphase CEMRA sequence (Time-Resolved Imaging of Contrast KineticS, TRICKS) was performed after intravenous injection of 0.1 mL/kg of the same GBCA at 3 mL/s flow rate (protocol B). Contrast enhancement was measured in the LA (LAe) and in the PA (PAe), and the LAe/PAe ratio was calculated. Diagnostic quality of Maximum Intensity Projection (MIP), Volume Rendering (VR), and Virtual Endoscopy (VE) reconstructions was also assessed visually using a semiquantitative score.LAe was comparable with both protocols, while PAe was lower with protocol B than with protocol A (p = 0.0217). Moreover, the LAe/PAe ratio was significantly higher with protocol B than with protocol A (p = 0.0044).Finally, image quality of MIP, VR, and VE reconstructions was significantly better with protocol B than with protocol A (p = 0.0005, p = 0.0001, and p = 0.005, respectively).CEMRA of the LA–PV complex is feasible with TRICKS and half-dose GBCA and yields better separation between the LA–PV complex and the PA, as well as better image quality of MIP, VR, and VE reconstructions than a conventional FSPGR sequence performed with full GBCA dose.

Preoperative vascular mapping with multislice CT of deep inferior epigastric artery perforators in planning breast reconstruction after mastectomy

Our aim was to evaluate the usefulness of computed tomography angiography (CTA) in vascular mapping for planning breast reconstruction after mastectomy using a free flap made with the deep inferior epigastric perforators (DIEP). We retrospectively evaluated 41 patients, mean age 57 years, scheduled for mastectomy. CTA was performed with a 64-row scanner (Aquilion 64, Toshiba Medical Systems, Japan), with injection of 100 ml of contrast medium (iomeprol 350 mgI/ml, Bracco, Italy) at 4.5 ml/s. Maximum intensity projection (MIP) and three-dimensional volume-rendering (VR) reconstructions were made to mark perforator positions. Presentation frequency, anatomy and artery opacification quality were evaluated. DIEP were always depicted (n=81) and subdivided according to Taylor's classification into type I (65%), type II (28%), and type III (7%). We observed a mean of three (range, 1-5) DIEP arteries on the right and two (range, 1-5) on the left side. The superficial inferior epigastric artery (SIEA) was depicted in 6/41 patients, bilaterally in three cases. Opacification was optimal in 30/41 cases, venous contamination due to late arterial phase in eight and low opacification due to early scan in three. Studying DIEP with CTA is useful in the surgical planning of breast reconstruction, even though it requires careful optimisation owing to the critical timing of opacification typical of that vascular district.

Effect of Three-Dimensional Computed Tomography Reconstructions on Reliability of Classification of Calcaneal Fractures

This study evaluated the impact of three-dimensional (3D) volume-rendering computed tomography (CT) reconstructions on the inter- and intraobserver reliability of six commonly used classification systems in the assessment of calcaneal fractures. Four independent observers with different levels of clinical training evaluated 64 fractures according to the classifications of the Orthopaedic Trauma Association (OTA), Essex-Lopresti, Sanders, Crosby, Zwipp, and Regazzoni, using two-dimensional (2D) CT scans with multiplanar reconstructions and 3D volume-rendering reconstructions. Interobserver reliability was moderate for the OTA, Essex-Lopresti, Sanders, Crosby, and Regazzoni classifications with 2D CT scans and 3D CT reconstructions. The Zwipp classification was poor with 2D CT scans and improved to moderate with 3D reconstructions. Intraobserver reliability with 2D CT scans was good for the Essex-Lopresti classification and moderate for the OTA, Sanders, Crosby, Zwipp, and Regazzoni classifications. After the addition of 3D reconstructions, all classifications showed moderate intraobserver reliability. According to the findings of this study, the additional use of 3D reconstructions is of minor value when used in conjunction with the classifications of the OTA, Sanders, Crosby, Regazzoni, and Essex-Lopresti. If calcaneal fractures are assessed with the Zwipp classification, 3D reconstructions could be used to achieve comparable reproducibility compared to other classifications. 3D reconstructions may have other benefits not evaluated in the presented study and may give useful information not captured by current classification systems.

3D morphometry of polyconitid rudist bivalves based on grinding tomography

Previous taxonomic studies have shown that polyconitid rudists have a characteristic arrangement of the myocardinal system with an ectomyophoral cavity on the posterior side of the left valve. The specific arrangement of the myophores and associated cavities defines the different genera. However, there has been little research on the three-dimensional spatial distribution and size of the internal features, for want of a technique that is suitable for large and low density-contrast specimens. The tomographic technique described herein is based on automatic serial grinding and serial scanning; the resulting images are treated with biomedical image software. The technique has been applied to a pair of well-preserved specimens of Polyconites verneuili from the Upper Aptian of Spain. Fifteen quantitative characters have been obtained using multiplanar virtual cuts, volume-rendering, and isosurfaces reconstructions. The study revealed the shape, size, and distribution of the ectomyophoral, body and accessory cavities, the lengths and volumes of the teeth, and the arrangement of the myophores. We conclude that this technique facilitates the description of rudist bivalves and is suitable for other fossils; moreover, it has the potential to be used in other fields of geology.

Computed tomography for detection and postoperative imaging of the left anterior descending artery occlusion incompletely visualized by conventional angiography

Fig. 1. LAO angiographic view failing to visualize the accurate course of distal LAD (black arrowheads) (A). CT curved multiplanar reconstruction demonstrating clearly the distal segment of LAD (B). Cx: circumflex artery; Dg: diagonal branch; LAD: left anterior descending artery. Fig. 2. CT sagittal maximum intensity projection performed 12 months after surgical revascularization confirmed good patency of the left internal mammary artery jump graft to the LAD (A). 3D volume-rendered reconstruction showing patent arterial jump graft to the LAD, first diagonal branch and second obtuse marginal branch (B). 3D volume-rendered reconstructions demonstrating non-stenotic anastomotic site to the LAD (C and D). LAD: left anterior descending artery; LIMA: left internal mammary artery.

Time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium–pulmonary veins complex with half dose of intravenous gadolinium-based contrast agent. Technical feasibility and comparison with a conventional CEMRA, full contrast dose protocol

To evaluate feasibility and image quality of time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium-pulmonary veins (LA-PV) complex with half dose of intravenous gadolinium-based contrast agent (GBCA) in patients candidate to percutaneous radiofrequency ablation of atrial fibrillation. Fifty-seven patients underwent CEMRA of the LA-PV complex on a 1.5T MRI scanner. On 24/57 patients, a conventional fast-spoiled gradient-echo (FSPGR) CEMRA acquisition was run using 0.2 mL/kg of 0.5M GBCA at 2 mL/s flow rate (protocol A), while in 33/57 patients a time-resolved multiphase CEMRA sequence (Time-Resolved Imaging of Contrast KineticS, TRICKS) was performed after intravenous injection of 0.1 mL/kg of the same GBCA at 3 mL/s flow rate (protocol B). Contrast enhancement was measured in the LA (LAe) and in the PA (PAe), and the LAe/PAe ratio was calculated. Diagnostic quality of Maximum Intensity Projection (MIP), Volume Rendering (VR), and Virtual Endoscopy (VE) reconstructions was also assessed visually using a semiquantitative score. LAe was comparable with both protocols, while PAe was lower with protocol B than with protocol A (p = 0.0217). Moreover, the LAe/PAe ratio was significantly higher with protocol B than with protocol A (p = 0.0044). Finally, image quality of MIP, VR, and VE reconstructions was significantly better with protocol B than with protocol A (p = 0.0005, p = 0.0001, and p = 0.005, respectively). CEMRA of the LA-PV complex is feasible with TRICKS and half-dose GBCA and yields better separation between the LA-PV complex and the PA, as well as better image quality of MIP, VR, and VE reconstructions than a conventional FSPGR sequence performed with full GBCA dose.

Multiple Tracheal Diverticula Detected by Multidetector-row Computed Tomography

Multiple tracheal diverticula are rare. We report a case of a 62-year-old man who had multiple tracheal diverticula that were detected using multidetector-row computed tomography. Axial computed tomography images showed multiple air collections contiguous to the trachea. The multiple air collections were visible as outpouchings of the parts of the trachea between the cartilages, being located almost symmetrically on both lateral sides of the tracheal wall as seen on coronal multiplanar reconstruction images. Virtual bronchoscopy confirmed the presence of multiple openings in the tracheal wall of the diverticular necks. The alteration of the airway was better seen using volume-rendered reconstruction. Thin-slice multidetector-row computed tomography and advanced imaging techniques may increase the frequency of identification of multiple tracheal diverticula.

The Type 4 DIEA: A Newly Identified Branching Pattern of the Deep Inferior Epigastric Artery

Sir: The deep inferior epigastric artery (DIEA) is a reliable vessel used routinely as the basis for DIEA perforator flaps, with anatomical variations infrequent and operative success widespread.1 Although the perforating branches of the DIEA may show significant individual variability in size, location, and course, the DIEA itself has been shown to be ever present as a vascular pedicle and highly dependable.1–3 Despite this consistency, the DIEA exhibits a variable branching pattern as it ascends cranially within the rectus sheath, with this pattern classified by Moon and Taylor in 1988 (Fig. 1) into three patterns: a single trunk (type 1), a bifurcating trunk (type 2), or trifurcating trunk (type 3).4Fig. 1.: Schematic diagrams of the original classification system of the branching patterns of the DIEA by Moon and Taylor. The DIEA is shown as a single, bifurcating, or trifurcating trunk below the umbilicus. The arcuate line is dotted. These schematics present the findings of the original study by Moon and Taylor. (Reproduced from Moon HK, Taylor GI. The vascular anatomy of rectus abdominis musculocutaneous flaps based on the deep superior epigastric system. Plast Reconstr Surg. 1988;82:815–829.)Previous studies assessing this anatomy have been limited by both postmortem analysis and the number of available cadaveric specimens; however, with the widespread use of preoperative imaging before abdominal wall free flaps, particularly with computed tomographic angiography, this anatomy has become routinely visualized in large numbers.5 We describe a unique case in which four major DIEA trunks were identified, suggesting a new addition to the current nomenclature. A 42-year-old woman presented for delayed autologous breast reconstruction following previous mastectomy for breast cancer. She underwent routine preoperative imaging with computed tomographic angiography, using a standardized protocol as reported previously.5 She had a body mass index in the normal range and had not undergone any previous abdominal surgery. Three-dimensional volume-rendered technique reconstructions of the computed tomographic angiograms were performed to demonstrate the DIEA, its branching pattern, and its communications. Multiple images were assessed to confirm major branches. The scan demonstrated bilateral DIEAs originating from the external iliac artery as a single trunk on each side. Although the left side ascended cranially as a single trunk (a type 1 branching pattern), the right side branched into four major branches above the arcuate line (Fig. 2). This finding does not fit the previous classification system by Moon and Taylor, but by extension would be classified as a “type 4” pattern.Fig. 2.: Computed tomographic angiogram, volume-rendered technique reconstruction of the anterior abdominal wall vasculature. The DIEA on the right side is shown to divide into four major trunks (type 4). The left-sided DIEA ascends as a single trunk (type 1).The DIEA is a consistent vessel supplying the lower anterior abdominal wall integument. Originating from the external iliac artery, the artery pierces the transversalis fascia to enter the rectus sheath. After supplying two large branches, a pubic branch that may represent an accessory obturator artery and an early muscular branch to the rectus abdominis, the artery ascends within the rectus sheath to display a variable branching pattern before anastomosing with branches of the deep superior epigastric artery. The Moon and Taylor nomenclature was the first such classification system described. Although this system describes three branching patterns of the DIEA, either a single, bifurcating, or trifurcating trunk,4 the current case highlights a fourth branching pattern. These variations in the branching pattern of the DIEA can have a significant impact on the surgical approach to DIEA perforator flap harvest, with perforators arising from a single branch preferred. Such an approach can spare rectus abdominis muscle damage, preserve vascular supply, and potentially spare motor nerve damage where a medial branch is harvested. DISCLOSURE The authors have no conflicts of interest to disclose. Warren M. Rozen, M.B.B.S., B.Med.Sc., P.G.Dip.Surg.Anat., Ph.D. Mark W. Ashton, M.B.B.S., M.D. Damien Grinsell, M.B.B.S. Jack Brockhoff Reconstructive Plastic Surgery Research Unit Department of Anatomy and Cell Biology University of Melbourne Parkville, Victoria, Australia

Flat-detector computed tomography with intravenous contrast material application in experimental aneurysms: Comparison with multislice CT and conventional angiography

Despite limited soft tissue resolution flat-detector computed tomography (FD-CT) provides substantial superior spatial resolution in comparison with multislice computed tomography (MS-CT). This may add value in the visualization of small vascular structures if intravenous contrast application leads to substantial opacification and visibility of intracranial vessels or aneurysms. To evaluate the feasibility of visualization of vascular structures by FD-CT angiography (FD-CTA) after intravenous contrast injection compared with MS-CTA and intra-arterial digital subtracted angiography (IADSA) in an animal model. Aneurysms were created in the right common carotid artery in six New Zealand White Rabbits using the elastase technique. Imaging was performed using FD-CTA, MS-CTA (injection of 1 ml/kg body weight) and IADSA. Anonymized volume rendering reconstruction (VRT), maximum intensity projection (MIP), and multiplanar reconstruction (MPR) images were reconstructed and evaluated by two experienced reviewers for aneurysm geometry and vascular structure anatomy using standard tools of a dedicated workstation. Aneurysms could be successfully created in all animals. Measurements of aneurysm geometry (aneurysm height, width, neck width) and vascular structures (brachiocephalic trunk, carotid artery diameter and plane) were nearly identical in all three modalities. Intra- and inter-observer correlations of the different parameters showed high r values between 0.83 and 0.99. Our results show the feasibility of FD-CTA in comparison with MS-CTA and IADSA in an animal model. Despite limited soft tissue resolution, opacification of vascular structures with sufficient contrast to the surrounding structures was possible in all animals. Vascular structures appeared better delineated in FD-CTA than in MS-CTA, probably due to the superior spatial resolution.