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PubMed2006

Evaluation of 3D Monte Carlo-based scatter correction for 99mTc cardiac perfusion SPECT.

UNLABELLED: Cardiac SPECT images are degraded by photons scattered in the thorax. Accurate correction for scatter is complicated by the nonuniform density and varied sizes of thoraxes and by the additional attenuation and scatter caused by female patients' breasts. Monte Carlo simulation is a general and accurate method for detailed modeling of scatter. Hence, for 99mTc we compared statistical reconstruction based on Monte Carlo modeling of scatter with statistical reconstruction that incorporates the more commonly used triple-energy-window scatter correction. Both of these scatter correction methods were used in conjunction with attenuation correction and resolution recovery. METHODS: Simultaneous attenuation, detector response, and Monte Carlo-based scatter correction were implemented via the dual-matrix ordered-subset expectation maximization algorithm with a Monte Carlo simulator as part of the forward projector (ADS-MC). ADS-MC was compared to (i) ordered-subset expectation maximization with attenuation correction and with detector response modeling (AD); (ii) like (i) but with scatter correction added using the triple-energy-window method (ADS-TEW). A dual-detector SPECT system equipped with 2 153Gd scanning line sources was used for acquiring 99mTc emission data and attenuation maps. Four clinically realistic phantom configurations (a large thorax and a small thorax, each with and without breasts) with a cardiac insert containing 2 cold defects were used to evaluate the proposed reconstruction algorithms. In these phantom configurations, we compared the performance of the algorithms in terms of noise properties, contrast-to-noise ratios, contrast separability of cold defects, and robustness to anatomic variation. RESULTS: Noise was found to be approximately 14% lower in the ADS-MC images than in the ADS-TEW and AD images. Typically, the contrast obtained with the ADS-MC algorithm was 10%-20% higher than that obtained with the other 2 methods. Furthermore, compared with the other 2 algorithms, the ADS-MC method was less sensitive to anatomic variations. CONCLUSION: Our results indicate that the imaging performance of 99mTc SPECT can be improved more by Monte Carlo-based scatter correction than by window-based scatter correction.

Computer Simulation↗

PubMed2003

Clinical predictors of long-term success after endoscopic sinus surgery.

OBJECTIVE: Determining the clinical predictors of long-term success after endoscopic sinus surgery (ESS) would better guide the management of patients. METHODS: One hundred-thirty chronic rhinosinusitis (CRS) patients were evaluated retrospectively. Overall subjective improvement was 83% with a mean follow-up of 60 months. Eighty percent had anatomic variations; 36.2%, allergy; 55.4%, nasal polyps; and 26.9%, history of previous operation. The improvement was 100%, 94%, 79.5%, and 69.7% in stages 0, I, II, and III, respectively. With other parameters, the success rates were 68.1% and 91.6% with and without allergy, 73.6% and 94.8% with and without polyps, 54.3% and 93.7% with and without previous history of surgery, 84.4% and 82.7% with and without anatomic variations, and 23.8% and 94.4% with and without recurrent polyps. CONCLUSION: In multivariate Cox regression analysis, allergy (P < 0.05; relative risk, 4.6) and previous polypectomy (P < 0.05; relative risk, 9.9) were found to be predictors of poor prognosis in the long-term follow-up.

Adolescent↗

PubMed1993

Introduction of a "safety zone" for the safety of laparoscopic cholecystectomy.

Anatomic variations of the biliary tract were found in 18 cases of 600 patients (3.0%) undergoing laparoscopic cholecystectomy. All bile duct anomalies were confirmed preoperatively by endoscopic retrograde cholangiography. In every case, the cystic duct and cystic artery were exposed in a "safety zone" near the gallbladder neck in Calot's triangle. Laparoscopic cholecystectomy was successfully performed on all 18 cases. Intraoperative cholangiography clearly demonstrated the anatomic variations in all cases, unequivocally identified the cystic duct, and confirmed the absence of bile duct injury. Preoperative endoscopic retrograde cholangiography and intraoperative cholangiography, which have been performed routinely in all patients, improve the safety of laparoscopic cholecystectomy. Moreover, the observance of the essential rule of "keep operating in the safety zone" protects against inadvertent complications, especially against bile duct injury during laparoscopic cholecystectomy. Laparoscopic cholecystectomy was thus successfully performed on all 600 cases in the present series, except for three cases, which were converted to open surgery (conversion rates, 0.5%), because of pin-hole bleeding on the portal vein in our first case of 600, and severe adhesion in two (46th and 302nd) cases.

Bile Ducts↗

PubMed2003

Root canal treatment of three-rooted maxillary first and second premolars--a case report.

AIM: To report the diagnosis and successful clinical management of a patient with anatomical variation in maxillary first and second premolars. SUMMARY: Maxillary premolars have a highly variable root canal morphology, but it is rare, especially in the second premolar, to find three canals. This article describes the diagnosis and clinical management of first and second premolars with three canals and three separate roots, drawing particular attention to radiographic interpretation and access refinements. KEY LEARNING POINTS: Clinicians should be aware of anatomical variations in maxillary premolars and be able to apply this knowledge in radiographic and clinical interpretation. Access cavity refinements may be required for stress-free entry to complex anatomy. Complex premolar anatomy may be predictably managed following its identification and negotiation.

Adult↗

PubMed1988

Donor renal angiography: its influence on the decision to use the right or left kidney.

The left kidney from a living, related donor is preferred for kidney transplantation because it has a longer renal vein and thus is easier to implant in the recipient. However, anatomic variations in the renal arteries occasionally dictate the choice of the right kidney instead. To determine the influence of angiographic findings on the decision to use the right or the left kidney for transplantation, we assessed the role of preoperative angiography in the evaluation of living, related kidney donors. The records of 81 potential renal donors who underwent arteriography were reviewed. Three patients did not undergo donor nephrectomy, for reasons unrelated to the results of arteriography. Of the remaining 78 patients, two-thirds (52) underwent left nephrectomy as planned. A right nephrectomy was performed in the other 26 donors. In 19 of these 26 patients (24% of the 78 who underwent nephrectomy), the right kidney was chosen because of anatomic variations in the renal arteries seen on arteriography. Right donor nephrectomy was performed in the remaining seven of the 26 patients because of venous or collecting-system variants in the left kidney in three and because of better anatomic compatibility with the recipient in the other four. We conclude that donor angiography will dictate the choice of kidney in approximately one-fourth of prospective renal donors.

Adolescent↗

PubMedDate not supplied

Bifid mandibular condyles: report of four cases.

UNLABELLED: Anatomic variations in the condylar morphology, like bifid mandibular condyles, are a relatively uncommon anomaly. We report four cases (two in patients and two in archived specimens) of bifid mandibular condyles with emphasis on their aetiopathogenesis and radiographic features. A case of bifid mandibular condyles in a patient with rheumatoid arthritis is reported which, to the best of our knowledge, is the first reported case in the literature. CLINICAL RELEVANCE: Anatomical variations, like bifid mandibular condyles, may mimic a fracture/tumour. Therefore, knowledge and awareness about this entity is important for a general dental practitioner.

Arthritis, Rheumatoid↗

PubMed1997

Versatility of the free anterolateral thigh flap for reconstruction of head and neck defects.

OBJECTIVE: The anterolateral thigh flap has many advantages in head and neck reconstruction. However, it has not yet come into widespread use because of the anatomic variations of its perforators. Herein, we describe a safe operative technique related to the patterns of the perforators and discuss its wide versatility. SETTING: A national cancer center hospital. PATIENTS: Thirty-eight anterolateral thigh flaps were transferred. Confirmation and dissection of the flap pedicle were simultaneously performed with tumor resection. The design and elevation of the flap were carried out immediately after the tumor resection was completed. RESULTS: From the study of the anatomic variations of the perforators, septocutaneous patterns were recognized in 10 cases (26.3%) and musculocutaneous patterns in 28 cases (73.7%). All flaps were easily and safely elevated with our techniques. Thirty-six flaps survived. Partial necrosis was noted owing to excessive thinning procedure in one patient and total necrosis was noted owing to venous thrombosis at the anastomosis part in another patient. CONCLUSIONS: We found that the anterolateral thigh flap has numerous advantages. It is possible to perform the flap elevation and the tumor resection simultaneously. The flap is generally thin and is suitable for reconstruction of intraoral defects. Combined flaps with neighboring tissues and other, distant flaps can be used. Furthermore, since our technique minimizes the problems of confirmation and dissection of the perforators, we conclude that this flap can be successfully used to repair a variety of large defects of the head and neck.

Adult↗

PubMed2005

Bifid mandibular canal: literature review and case report.

OBJECTIVES: The objective is to call attention to and to review the literature of the anatomical variation: bifid mandibular canal. METHODS: A review of the literature is summarized. Additionally, the clinical and radiographic findings of a patient who presented a unilateral bifid mandibular canal are recorded. RESULTS: Bifid mandibular canals can be detected on a panoramic radiograph. More precise information about the course of the canal can be revealed on cross sectional CT images perpendicular to the alveolar ridge. CONCLUSIONS: Bifid mandibular canals are often unrecognized. The detection of these anatomical variations is important because of its clinical implications. Special attention has to be paid in surgical procedures involving the lower jaw.

Adult↗

PubMed2006

Living-donor hepatectomy in right-sided round-ligament liver: importance of mapping the anatomy to the left medial segment.

Left-sided gallbladder (LSGB) and right-sided round ligament (RSRL) are very infrequent findings, mostly described in Oriental patients, that have associated anatomical variations. An abnormal portal vein branching, mainly to segment IV, is strongly associated with RSRL. Living-donor liver transplantation requires that both the graft and the remnant liver have adequate vascular supply and volumes. Abnormal vascularization of segment IV then threatens this goal. There have been scarce reports of the feasibility of living-donor hepatectomy under these conditions, all in Oriental populations. We present a case of an Occidental living liver donor with RSRL, and discuss the associated anatomical variations of the portal vascular supply of the liver, with its implications in planning a living-donor hepatectomy.

Adult↗

PubMed1986

A mathematical model of the flow in the circle of Willis.

A mathematical model of the flow in the circle of Willis has been designed and the effects of (a) the large anatomical variation of the communicating arteries and (b) physiological changes of the resistances of the vertebral arteries have been studied. The influence of the posterior perforating arteries on the flow in the posterior communicating arteries has been investigated as well, with special attention being paid to the possible occurrence of a 'dead point'. In the model, the influence of diameters of the communicating arteries on the flow in the afferent vessels and the segments of the circle turns out to be considerable, especially in the range of the anatomical variation of the diameters. Within this range flow reductions due to an increased resistance of the vertebral artery will be compensated for by the system. Assuming that the values and ratios of the peripheral resistances are within the physiological range, a dead point is not to be expected in the flow in the posterior communicating arteries.

Cerebrovascular Circulation↗

PubMedDate not supplied

Evaluation of the hepatic artery in potential donors for living donor liver transplantation by computed tomography angiography using multidetector-row computed tomography: comparison of volume rendering and maximum intensity projection techniques.

PURPOSE: To compare the volume rendering (VR) and maximum intensity projection (MIP) computed tomography angiography (CTA) techniques using multidetector-row CT for hepatic artery evaluation of potential donors for living donor liver transplantation (LDLT). METHOD: Over a 9-month period, CTA using multidetector-row CT and conventional angiography was performed in 62 consecutive potential donors for LDLT. Acquisition of arterial phase scans was initiated within 5 seconds after reaching enhancement of the descending aorta up to 70 HU as measured by a bolus-tracking technique (collimation = 1.25 mm, table speed = 7.5 mm, reconstruction interval = 0.625 mm). Postprocessing was performed on a commercially available workstation. Computed tomography angiography images of the hepatic artery were made using the VR and MIP techniques. A total of 10 to 30 images of various planes were generated to reveal the origins and branching patterns of hepatic arteries. With a 2-week interval, two reviewers separately evaluated CTA using VR and MIP techniques, specifically evaluating anatomic variations and hepatic arterial conspicuity. The results of conventional angiography were considered to represent the gold standard. The difference in postprocessing time between the two techniques was statistically analyzed by the Student t test, and the differences in arterial conspicuity and in the identified number of the hepatic artery to segment IV of the liver were analyzed by the chi2 test. RESULTS: Two CT examinations (3%) were technically inadequate for generating CTA because of respiratory motion artifact. The average times for postprocessing of VR and MIP images were 8.1 +/- 3.8 minutes and 5.0 +/- 0.7 minutes, respectively. Variations of hepatic arterial anatomy were present in 19 patients (32%) on conventional angiography. In 8 patients (13%), there was discrepancy in the variations of hepatic arterial anatomy between the two techniques: MIP was correct in 7 patients, and VR was correct in 1 patient. The dominant artery supplying segment IV was identified in 51 patients (85%) with MIP and in 39 patients (65%) with VR. There was no significant difference in conspicuity of the hepatic arteries using either the MIP or VR technique. CONCLUSION: In CTA techniques using multidetector-row CT, MIP is superior to VR for the hepatic arterial evaluation of potential LDLT donors in terms of depicting anatomic variations and postprocessing time.

Adolescent↗

PubMed2004

Radiological study of the intumescentia septi nasi anterior.

Intumescentia septi nasi anterior (ISNA) is a common anatomical variation that is not routinely noticed by surgeons or radiologists. ISNA is a mucosal bulging located on each side of the anterior part of the septum. The aim of this study was to investigate the prevalence of ISNA in different ages and sexes. In this study, computerized tomography (CT) scans of the paranasal sinus were obtained from 595 patients who had symptoms of chronic sinusitis. Among 595 subjects, ISNA was found in 332 (55.79 per cent) of subjects. It was found more frequently in males than females in every age group. Although ISNA is a common anatomical variation, it is generally overlooked. This is the first report on ISNA in different age groups and sexes.

Adolescent↗

PubMed2002

Versatility of the free anterolateral thigh flap for reconstruction of soft-tissue defects: review of 140 cases.

From August 1995 to June 1999, 140 free anterolateral thigh (ALT) flaps were transferred to reconstruct a variety of soft-tissue defects. The size of ALT flap ranged from 10 to 33 cm in length and 4 to 14 cm in width. Based on the anatomic variations of the perforators, the blood supply to the skin island came from the septocutaneous perforators only in 19 patients (13.6%), arising from the descending or transverse branch of the lateral circumflex femoral artery (LCFA), or originating directly from LCFA. The other flaps were supplied by musculocutaneous perforators that were elevated as a true perforator flap via intramuscular dissection (N = 34, 24.3%), or used a cuff of vastus lateralis muscle for added bulk (N = 87, 62.1%). The overall success rate was 92% (129 of 140). After a 2-year follow-up, all flaps have healed unevenffully and donor thigh morbidity is minimal. Anatomic variations must be considered if the ALT flap is to be used safely and reliably.

Adult↗

PubMedDate not supplied

[The middle turbinate as the cause of sinusal pathology].

The middle turbinate and its anatomical variations (concha bullosa and paradoxically bent middle turbinate) may be the site of different pathologies due to the alteration of the sinus function at the key area of the osteomeatal complex. In the present work we study 4 cases of concha bullosa and 4 cases of paradoxically bent middle turbinates, associated to recurrent sinusitis and/or headaches, which underwent endoscopic surgery. Improvement was achieved in all recurrent circumscribed sinusitis. One of the patients with bilateral paradoxically bent middle turbinate had an associated pansinusitis, and he only improved in his right side. An aspergilloma was found inside one of the conchae bullosae. Headaches improved in all the cases analyzed. Anatomic variations may be the cause of recurrent sinusal pathology or isolated headaches and it should be noted that, in correctly selected groups, a dramatic improvement can be achieved with a minor surgical procedure on the middle turbinate or ethmoidal infundibulum.

Adolescent↗

PubMedDate not supplied

Virtual CT cholangiography in patients with choledocholithiasis.

BACKGROUND: We evaluated the feasibility and accuracy of virtual computed tomographic cholangiography (VCTC) in detecting choledocholithiasis and imaging anatomic variations of the biliary tree. METHODS: Thirty-three consecutive patients with clinical and biological signs of choledocholithiasis underwent spiral CT after intravenous infusion of iotroxindimeglumine. Patients with total serum bilirubin levels above 3 mg/dL were not included in this study. Spiral data sets were used to construct intralumenal images of the biliary tree. The images were reviewed by two abdominal radiologists. The biliary ducts were divided into three segments, so the analysis was based on 99 segments. The diagnosis obtained by VCTC was compared with the final diagnosis established by endoscopic retrograde cholangiography or intraoperative cholangiography. RESULTS: VCTC correctly depicted biliary stones in nine of 10 patients and anatomic variations in all five patients, and no false-positive cases were observed. VCTC showed excellent endolumenal visualization of 87 of 99 segments of the biliary tree. The processing time (9.3 +/- 2.1 min) was particularly short. CONCLUSION: VCTC with intravenous infusion of iotroxindimeglumine may be a feasible clinical tool, with acceptable accuracy in selected cases.

Cholangiography↗

PubMed1992

Injury to an accessory bile duct during laparoscopic cholecystectomy.

Anatomic variations of the bile duct system are frequent. Accessory cholecystohepatic ducts have been reported, but remain unrecognized in most patients. We present the case of an 53-year-old woman suffering from cholecystolithiasis. Five days after laparoscopic cholecystectomy, symptomatic bile collection in the peritoneal cavity was found. Endoscopic retrograde cholangio-pancreatography (ERCP) with papillotomy showed a bile leak in the gallbladder bed. During relaparoscopy, we were able to identify and to clip an accessory bile duct in the caudal part of the gallbladder bed. Symptomatic injury of an accessory bile duct is a rare complication of laparoscopic cholecystectomy and difficult to prevent. Intraoperatively we recommend the use of operative cholangiography to reveal anatomic variations. Postoperatively the leak can be identified by ERCP, but sphincterotomy should be done simultaneously. If necessary, however, the injury can be repaired by laparoscopic means.

Bile Ducts↗

PubMed2005

The posterolateral corner of the knee: evaluation under microsurgical dissection.

PURPOSE: The posterolateral corner (PLC) has been described by several authors, but there are still controversies. We assumed that a microanatomic dissection of this region could answer some of the questions about its complex anatomy. We therefore conducted an anatomic study using microsurgical techniques, aiming at a precise anatomic description of all the structures that form the posterolateral complex. TYPE OF STUDY: Cadaveric study. METHODS: Ten fresh-frozen human adult cadaveric knees were used for the study. Dissection of the knees was performed using microsurgical instruments, magnifying loupes, and an operative microscope. Anatomic variations, ligament shape, separated bundles of the ligaments, and topography of ligament attachments were described and recorded. RESULTS: The rate of the presence of the popliteofibular ligament (PFL), the fabellofibular ligament, and the arcuate ligament were 100%, 40%, and 70%, respectively. The connective attachments of the popliteus muscle to the other posterolateral structures are the PFL and the 2 popliteomeniscal fascicles. Our dissections show that the shape and the fibula attachment of the PFL can vary. Using the surgical microscope, we were able to dissect and identify 2 different fiber groups of the popliteus tendon at its attachment to the lateral femoral condyle. Also, we were able to confirm in 20% of our knees an anatomic variation of the lateral collateral ligament. CONCLUSIONS: Our study may answer some of the questions about the complex anatomy of the PLC. The PFL is well established, always recognizable, and significant in size. CLINICAL RELEVANCE: Being aware of the complex anatomy of the posterolateral corner and its variations may prove useful in repair and reconstruction.

Adult↗

PubMed1990

Anterior tibial tendon insertion: an anatomical study.

Anatomical variations of the anterior tibial tendon insertion were studied by dissection in 44 normal feet of 22 embalmed adult cadavers. Three types of insertion were found. The most common insertion (56.8%) was a division of the tendon into two slips, equal in width, the one slip being inserted into the first cuneiform and the other slip into the base of the first metatarsal. The next most common (27.3%) was a division of the tendon into a large slip, inserted into the first cuneiform, and a small slip, inserted into the base of the first metatarsal. The third type, and least common tendon insertion (15.9%), was by a single slip into the first cuneiform only. Knowledge of these anatomical variations will assist surgeon in performing anterior tibial tendon transposition for recurrent congenital clubfoot.

Adult↗