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Results for “Anatomic Landmarks”

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PubMed2005

Tympanomastoid suture and digastric muscle in cadaver and live parotidectomy.

OBJECTIVES/HYPOTHESIS: To prove that the tympanomastoid suture (TMS) is a significantly closer and less variable anatomic landmark to the facial nerve than the posterior-superior margin of the posterior belly of the digastric muscle (PBD) in parotid surgery. MATERIALS AND METHODS: A prospective study of 14 cadaver specimens and 22 live patients comparing the closest measured distances between the TMS and PBD to the facial nerve. RESULTS: The mean closest distances from the TMS and PBD to the facial nerve were 1.8 (range 0-4) mm and 12.4 (range 7-17) mm, respectively (P < .05) for cadavers. The mean closest distances in live patients from the TMS and PBD to the facial nerve were 2.0 (range 0-4) mm and 10.7 (range 5-14) mm, respectively (P < .05). CONCLUSIONS: Facial nerve identification and preservation is the key to successful parotid surgery. The TMS is a significantly closer and less variable anatomic landmark compared with the PBD both in cadaver dissection and in live patients.

Cadaver↗

PubMed2006

The high variability of tibial rotational alignment in total knee arthroplasty.

Although various techniques are advocated to establish tibial rotational alignment during total knee arthroplasty, it is unknown which is most repeatable. We evaluated the precision and accuracy of five tibial rotational alignment techniques to determine whether computer-assisted navigation systems can reduce variability of tibial component rotational alignment when compared to traditional instrumentation. Eleven orthopaedic surgeons used four computer-assisted techniques that required identification of anatomical landmarks and one that used traditional extramedullary instrumentation to establish tibial rotational alignment axes on 10 cadaver legs. Two computer-assisted techniques (axes between the most medial and lateral border of the tibial plateau, and between the posterior cruciate ligament [PCL] and the anterior tibial crest) and the traditional technique were least variable, with standard deviations of 9.9 degrees, 10.8 degrees, and 12.1 degrees, respectively. Computer-assisted techniques referencing the tibial tubercle (axes between the PCL and the medial border or medial 1/3 of the tubercle) were most variable, with standard deviations of 27.4 degrees and 28.1 degrees. The axis between the medial border of the tibial tubercle and the PCL was internally rotated compared to the other techniques. None of the techniques consistently established tibial rotational alignment, and navigation systems that establish rotational alignment by identifying anatomic landmarks were not more reliable than traditional instrumentation.

Arthroplasty, Replacement, Knee↗

PubMed1996

Correlation between karyotype and ultrasound findings in patients with failed early pregnancy.

The aim of this retrospetive study was to identify any consistent patterns between ultrasound findings in failed pregnancies and either normal or abnormal karyotypes. The study involved 102 women in whom the diagnosis of early pregnancy failure was made sonographically. The criteria for a failed pregnancy were: a gestational sac with a mean diameter of > 12 mm without a yolk sac; a yolk sac of > 6 mm mean diameter with or without abnormal morphology that ultimately failed to develop an embryonic structure; and an embryo with a crown--rump length (CRL) of > 5 mm without cardiac activity, or the loss of previously identified cardiac activity. All patients underwent elective dilatation and curettage (D & C) and products of conception were sent for karyotyping. Forty-four pregnancies (43%) had abnormal karyotypes. Of these, 33 (75%) were trisomies. The other 11 included four triploidies, one tetraploidy, two with monosomy X, and four others (unbalanced complement, isochromosome, terminal deletion and translocation). Fifty-eight pregnancies (57%) had normal karyotypes, of which 52 were 46,XX and six were 46,XY. The furthest sonographic anatomic landmark achieved did not differ with respect to karyotypic findings. An abnormal yolk sac was found in 10/58 cases (17.2%) with normal karyotypes and 8/44 cases (18.2%) with abnormal karyotypes. There were eight cases of trisomy 16, of which only two manifested an embryonic structure, but neither of which had cardiac activity; the largest was 4 mm. There were four cases of trisomy 22, of which three developed embryos with a CRL of > 10 mm with cardiac activity (11, 11 and 18 mm, respectively). In three cases of mosaicism, embryos developed cardiac activity, and were 9, 19 and 16 mm. Two cases of monosomy X had embryos of 14 and 24 mm. Only one out of five cases with multiple trisomies developed to a point at which any embryonic structure was identifiable on ultrasound examination. The ultrasound appearance of early pregnancy failure in terms of furthest anatomic landmark reached was not significantly different in cases with normal or abnormal karyotype. An abnormally enlarged yolk sac, presumably secondary to hydropic change, is a non-specific finding of failed pregnancy, and did not correlate with karyotypic abnormality (trisomy 22, mosaic, monosomy X) seem to develop further prior to embryonic demise than those with certain others (trisomy 16, multiple trisomies and unusual other variants.

Abortion, Spontaneous↗

PubMed2004

Effects of geometric distortion in 0.2T MRI on radiotherapy treatment planning of prostate cancer.

BACKGROUND AND PURPOSE: To evaluate the impact of two different methods of geometric distortion correction of MR images from a Siemens Magnetom Open Viva 0.2T resistive MR unit on the process of external beam radiotherapy treatment planning for prostate cancer. PATIENTS AND METHODS: A method for correction of system related and object induced distortions and one for correction of purely system related distortions have been evaluated. The latter used information extracted from MR images of a 3D phantom specifically designed for geometric distortion evaluation. An active shim procedure was performed prior to all phantom and patient scans. For each of five patients five standard treatment plans were compared using uncorrected and corrected MR images alone (density=water) and CT images alone. Finally internal anatomical landmarks were used for image registration between MR images (corrected and uncorrected) and CT images to evaluate the impact of distortion correction on the image registration process. RESULTS: Maximum distortions of 28 mm (mean 2.2 mm) were found within the FOV in frequency encode direction. Maximum distortions could be reduced by a factor of two (mean factor four) by our phantom measurement based technique. Distortion patterns were found to be stable and reproducible over several weeks with this MR unit. For 4/5 patients, relative doses at the normalization point as calculated on the distortion corrected MR images only (all tissues taken water equivalent) were all within 1% of the corresponding value from the standard CT-based plan (actual Hounsfield units). The largest differences in isocentric dose found in one case were 3.1% MR uncorrected vs. CT and 2.6% MR corrected vs. CT. Typical sites of internal anatomical landmarks chosen for image registration show distortions up to 3 mm. CONCLUSIONS: Object induced distortions are negligible at such low field strengths compared to system related distortions. Treatment plans for prostate cancer do not seem to differ significantly from "standard" plans calculated on CT images when calculated on distortion corrected MR images, even if all tissues are assigned the electron density of water. Distortion correction of MR images can theoretically improve the starting point for image registration of MR and CT images.

Humans↗

PubMed1994

Radiofrequency catheter ablation guided by intracardiac echocardiography.

BACKGROUND: Radiofrequency catheter ablation requires precise positioning of the ablation electrode. Fluoroscopically guided catheter manipulation has limitations, and there are risks of radiation exposure. The purpose of this study was to examine the feasibility of guiding catheter ablation within the right atrium with catheter-based intracardiac echocardiography. METHODS AND RESULTS: A 10F, 10-MHz intracardiac imaging catheter was used to direct an ablation electrode at four or five anatomic landmarks in the right atrium. Thirty-eight radiofrequency energy applications were performed in nine anesthetized dogs, and 38 lesions were identified on pathological examination. Lesions were created a mean of 1.9 +/- 2.1 mm from the ultrasound-guided site. Twenty-six of 38 lesions (68%) were less than 2.2 mm from the imaged site. Intracardiac echocardiography also was used to confirm stable electrode-endocardial contact in 37 energy applications (97%) and identified catheter movement in 9 energy applications (24%). Discrete lesions, microcavitations, and thrombi were observed in 13 (34%), 23 (61%), and 19 (50%) of 38 energy applications, respectively. Microcavitations predicted the appearance of thrombus. Fluoroscopy time required to create four or five lesions decreased from 23 minutes in the first study to less than 2 minutes in the last five studies. CONCLUSIONS: Catheter-based intracardiac echocardiography can accurately guide catheter ablation directed at anatomic landmarks and potentially reduced ionizing radiation exposure. Intracardiac imaging can be used to confirm endocardial contact, identify electrode movement, and directly visualize lesions. Intracardiac echocardiography also can be used to identify microcavitations, which predict thrombus formation during radiofrequency energy applications.

Animals↗

PubMed2004

An anteroposterior axis of the tibia for total knee arthroplasty.

The objective of the current study was to identify a new extraarticular anatomic landmark indicating the anteroposterior orientation of the tibia using computed tomography. In 39 volunteers (20 males, 19 females), computed tomography scans for healthy right knees in extension were done perpendicular to the tibial shaft axis. The anteroposterior axis of the tibia was defined as a line perpendicular to the transepicondylar axis and passing through the middle of the posterior cruciate ligament. At the level of the tibial plateau and the patellar tendon attachment, the mean medial percentage width of intersecting point of the patellar tendon and the anteroposterior axis was 10.8% +/- 9.8% (range, -9.3% - +30.0%) and -0.2% +/- 10.4% (range, -23.6% -+23.0%), respectively. The mean angle between the anteroposterior axis and a line connecting the middle of the posterior cruciate ligament to the medial border of the patellar tendon attachment was 0.0 degrees +/- 2.8 degrees (range, -6.3 degrees -+5.2 degrees). The medial border of this attachment therefore can serve as a reliable anterior anatomic landmark to determine the anteroposterior axis of the tibia, and the line connecting the middle of the posterior cruciate ligament and the medial border of the attachment may be useful as a reference axis indicating the anteroposterior orientation of the tibia.

Adult↗

PubMed2003

Positioning internal jugular venous catheters using the right third intercostal space in children.

BACKGROUND: Central venous catheters are used for pressure measurement, and drug and fluid therapy in children. Several reports have described serious complications related to catheter positioning. We evaluated the possibility of using the right third intercostal space as an anatomic landmark for determining the optimal insertion depth of a central venous catheter from the right internal jugular vein. METHODS: The distance between the skin puncture site and the right third intercostal space (SK-ICS) was measured in 83 children. The catheter was inserted to a depth equal to the measured distance. Postoperatively, the distance between the catheter tip and the radiographic junction of the superior vena cava and the right atrium was measured. This was defined as the optimal catheter length, which placed the catheter tip at the SVC/RA junction (SK-SVC/RA). RESULTS: A significant correlation was found between the SK-ICS and SK-SVC/RA (regression equation: SK-SVC/RA = 0.35 + 0.98 x SK-ICS, r2 = 0.8554). Based on the data obtained, a simple formula, SK-ICS-1 (cm), predicted that a CVC would be positioned above the RA in 98.8% of patients. CONCLUSIONS: Using the right third intercostal space as an anatomic landmark allows positioning of the catheter tip in the SVC near to but not in the RA in children.

Catheterization, Central Venous↗

PubMed2005

The clinical risk of vertebral artery injury from cervical pedicle screws inserted in degenerative vertebrae.

STUDY DESIGN: Postoperative outcomes of cervical pedicle screw (CPS) placement were evaluated. The screws were inserted in degenerative vertebrae using anatomic landmarks. OBJECTIVE: To evaluate the risks of this procedure caused by misplacements and subsequent complications. SUMMARY OF BACKGROUND DATA: The CPS gives superior vertebral fixation but risks causing vertebral artery and spinal cord injury. However, few clinical reports have been published concerning CPS misplacement and subsequent complications. Therefore, the risk of this procedure is still unclear. METHODS: There were 18 consecutive patients, who submitted to CPS fixation of degenerative vertebrae C2-C6, evaluated using computerized tomography (CT). In 5 of 9 patients in whom the screw critically violated the transverse foramen, viability of the vertebral artery was evaluated using multi-detector row CT angiography. RESULTS: There were no intraoperative vertebral artery or spinal cord injuries and no serious postoperative complications. A total of 86 screws were inserted, and 25 (29%) breached the pedicle cortex. Of them, 84% deviated laterally and violated the transverse foramen. There were 13 screws (15%) that deviated more than 2 mm. However, multi-detector row CT angiography showed the continuity of the vertebral artery in all cases. CONCLUSIONS: The deviation rate of CPS placement using anatomic landmarks was higher than anticipated, although no serious complications were encountered. Refinement of the technique (e.g., using a computer-assisted navigation system) is strongly recommended.

Adult↗

PubMed2001

Radiofrequency catheter ablation of idiopathic left ventricular outflow tract tachycardia: utility of intracardiac echocardiography.

INTRODUCTION: The site of origin of idiopathic ventricular tachycardia (VT) arising from the left ventricular outflow tract (LVOT) may be closely related to the aortic valve leaflets, and radiofrequency (RF) delivery potentially can damage them. Intracardiac echocardiography (ICE) can identify accurately the ablation electrode and anatomic landmarks, and contact with the endocardium can be easily assessed. The aim of this study was to define the utility and the accuracy of ICE in guiding RF ablation of idiopathic VT of the LVOT. METHODS AND RESULTS: Five consecutive patients (all men; mean age 20.4 years, range 16 to 25) symptomatic for idiopathic VT underwent RF ablation. A 9-French, in-sheath catheter with a 9-MHz ultrasound transducer was inserted through the femoral vein and positioned in the His-bundle region or right ventricular outflow tract to provide a clear view of the aortic root. Local earliest ventricular activation during tachycardia and pace mapping were used to identify the ablation site. Idiopathic VT was ablated successfully in all patients using a median of two RF pulses, delivered during tachycardia. High-resolution images of the aortic valve and ablation electrode were achievable in all cases. Direct vision of ablation electrode-endocardial contact in the outflow tract was assessed easily in all patients. CONCLUSION: Idiopathic VT of the LVOT can be treated successfully with RF ablation. ICE can accurately guide catheter ablation and identify anatomic landmarks, endocardial contact, and ablation electrode movement.

Adolescent↗

PubMed2001

The vascular anatomy anterior to the L5-S1 disk space.

STUDY DESIGN: Dissection of 37 human cadavers was performed to assess the variability in the vascular anatomy anterior to the L5-S1 disc space. OBJECTIVES: To determine the variability of the anterior vascular anatomy at the L5-S1 disc space, and to assess its reliability as an anatomic landmark for the placement of anterior interbody fusion devices. SUMMARY OF BACKGROUND DATA: Although multiple studies have defined both the lumbar spinal anatomy and the anatomy of the great vessels, the relation of the great vessels to the anterior L5-S1 disc space has not been quantified directly. METHODS: This study investigated 35 human cadavers (17 males and 18 females). The anterior L5-S1 disc space and great vessel bifurcation were exposed through a transabdominal approach. Two independent observers each obtained 10 measurements in each specimen. RESULTS: The middle sacral artery was present in 100% of the specimens, averaging 2.5 mm in width. Its location in relation to the midline was quite variable, with a range greater than 2 cm in both the top and bottom of the disc. The distance from the bifurcation to the top of the L5-S1 disc averaged 18 mm (range, 7-36 mm). The total width between the left common iliac vein and the right common iliac artery averaged 33.5 mm (range, 12-50 mm). CONCLUSIONS: The middle sacral artery, present in 100% of the specimens, is a poor anatomic landmark for locating the midline at L5-S1. Because the average space available between the left common iliac vein and the right common iliac artery is 33.5 mm, and because the left common iliac vein averages only 12 mm from midline, the surgeon must be prepared to mobilize the local vasculature in most cases to expose the L5-S1 disc space adequately.

Aged↗

PubMed2000

Comparison of two-dimensional and three-dimensional techniques for determination of facial motion--absolute movement in a local face frame.

BACKGROUND AND PURPOSE: Few studies have used motion analysis in the study of facial animation. A facial animation model using an expert vision motion analysis system was developed in this study to quantitatively evaluate absolute movement during five facial animations. METHODS: Skin markers were adhered to the face of each subject at 16 anatomic landmarks selected to represent the functional movement of the facial muscles. Three of the 16 skin markers were used to establish a local face frame with the origin in the mid-point of the face. All of the coordinates measured in the laboratory frame were rotated and translated to the local face frame for analysis. The trajectory of the facial markers was evaluated from the local face frame when comparing two-dimensional (2-D) displacement of skin markers (frontal plane) with three-dimensional (3-D) values by paired Student's t-test. RESULTS: Although the correlation of 2-D and 3-D displacements of skin markers was high (r > 0.69), the differences between 2-D and 3-D motion were significant (p < 0.001). The 2-D displacement of skin markers underestimated the 3-D facial animation in each marker and animation. There were no significant differences in the movement of both mouth angles or of the eyes. Thirty repeated measurements of a subject revealed good concentration in 3-D displacement, velocity, and angle of movement in smiling. The measurement error was less than 0.06 mm. The normative displacement of individual anatomic landmarks was evaluated to avoid size differences of individual faces. CONCLUSIONS: We suggest that the expert vision motion analysis technique is feasible for quantitative evaluation of absolute facial movement and would be useful for further clinical evaluation of patients with facial palsy.

Adult↗

PubMed2005

Measurement of the spatial shift of the pupil center.

PURPOSE: To evaluate the effectiveness of the pupil center as an anatomic landmark for excimer laser treatments. SETTING: Sekal-Microchirurgia-Rovigo Centre, Rovigo, Italy. METHODS: Pupillometry with the Costruzione Strumenti Oftalmici S.R.L. (CSO) pupil-measuring module (incorporated in Eye Top videokeratoscope) was performed in 52 patients with a diagnosis of myopia and in 25 patients with a diagnosis of hyperopia. Measurements both in mesopic and photopic conditions consisted of pupil diameters, spatial shift of the pupil center, and the distance between the pupil center and keratoscopic axis. RESULTS: The mean pupil diameter in photopic conditions of illumination in myopic eyes was 3.52 mm +/- 0.56 (SD), while in mesopic conditions it was 5.37 +/- 0.78 mm; in hyperopic eyes the mean photopic pupil diameter was 3.01 +/- 0.46 mm, while the mean mesopic diameter was 5.12 +/- 0.48 mm. The mean spatial shift of the pupil center in myopic eyes was 0.086 mm (maximum 0.269 mm), while in the hyperopic eyes it was 0.095 mm (maximum 0.283 mm). The mean distance between the pupil center and keratoscopic axis in myopic eyes was 0.226 +/- 0.13 mm (maximum 0.75 mm), while in hyperopic eyes it was 0.45 +/- 0.19 mm (maximum 0.8 mm). CONCLUSIONS: The mean of the measured pupil sizes was greater in myopic eyes than in hyperopic eyes. The spatial shift of the pupil center, as the pupil dilates, was relatively small in all groups; therefore, the pupil center is a good anatomic landmark for both traditional refractive surgery and wavefront-guided treatments. The mean distance between the keratoscopic axis and pupil center was greater in the hyperopic group than in the myopic group. Therefore, centration of any laser treatment on the basis of the keratoscopic analysis should be done carefully, especially in hyperopic eyes and in cases in which the pupil center is meaningfully shifted from keratoscopic axis, even in photopic conditions of illumination.

Adolescent↗

PubMed2001

Microsurgical anatomy of the superior and recurrent laryngeal nerves.

OBJECTIVE: To study the microsurgical anatomy of the superior laryngeal nerve (SLN) and recurrent laryngeal nerve (RLN) with respect to anatomic landmarks, and to identify their vascular supplies. METHODS: The microsurgical anatomy of the anterior neck, the course of the right and left SLN and RLN and their variations were studied in 21 cadavers. Fresh cadavers were perfused with colored silicon dye to investigate the microvasculature in detail. RESULTS: SLN originates from the inferior vagal ganglion at the C2 level and descends medially toward the thyrohyoid membrane. It branches into an external and an internal branch deep to the internal carotid artery at the C3 level. The external branch, along with the cricothyroid artery, descends deep to the superior thyroid artery toward the cricothyroid muscle. Accompanied by the superior laryngeal artery, the internal branch passes deep to the loop of the superior thyroid artery and pierces the thyrohyoid membrane. Both nerves reside in the fascia covering longus colli muscles and are supplied by their accompanying arteries. The loop of RLN is found at the T1-T3 level on the right, and more caudally at the T3-T6 level on the left, entering the larynx between C5-C7 levels on both sides. RLN receives arterial supply from the esophageal and tracheal branches of the inferior thyroid artery proximally, and by the inferior laryngeal artery distally. CONCLUSION: Incidental intraoperative injury to the SLN and RLN potentially could be avoided by understanding the detailed course of each nerve with respect to the surrounding anatomic landmarks and by recognizing their blood supplies.

Aged↗

PubMed2006

Anatomic guides to precisely localize the zygomatic branches of the facial nerve.

UNLABELLED: Descriptions of superficial anatomic landmarks for the identification of the zygomatic branches of the facial nerve, and their relevance for plastic surgery, are lacking in the literature. This paper provides such a description and discusses its relevance to facial surgery. MATERIALS AND METHODS: Sixty-six specimens, including the parotid region, from 33 adult cadavers were dissected and studied. All specimens were fixed in formaldehyde, and the superficial tissues were removed and the zygomatic branches of the facial nerve, the parotid gland, the tragus and the lateral palpebral commissure were identified. The vertical and horizontal relationships were recorded and analyzed. RESULTS AND CONCLUSIONS: A total of 69.7% of the cadavers had two branches, 25.8% had three branches, and 4.5% had a single zygomatic branch. The mean horizontal distance of the zygomatic branch (the most upper one) as it emerged from the anterior border of the parotid gland and the tragus was 30.71 mm, whereas the mean vertical distance of the zygomatic branch from the midpoint between the tragus and the lateral palpebral commissure was 19.29 mm. The branching patterns with the buccal branches were reported. There were no statistical differences between the left and right sides or between the sexes. The zygomatic branches of the facial nerve were always under the oblique line between the tragus and the lateral palpebral commissure and have a close relationship with the buccal branches of the facial nerve under this anatomic landmark. Application of the results in facial surgery is discussed.

Adult↗

PubMed2004

Prospective evaluation of thoracic pedicle screw placement using fluoroscopic imaging.

BACKGROUND: In this prospective 18-month study, 29 patients underwent posterior thoracic instrumentation with placement of 209 transpedicular screws guided by intraoperative fluoroscopic imaging and anatomic landmarks. We assessed the safety, accuracy, complications, and early stability of this technique. METHODS: Pedicle and pedicle-rib units were measured, and screw cortical penetrations were graded on anatomy and depth of penetration. All 29 patients underwent preoperative computed tomographic (CT) imaging, and 28 underwent postoperative CT imaging (199/209 screws). RESULTS: From T2 to T12, screw diameters were >or=5 mm with mean medial screw angulation measuring 20-25 degree. Of the 209 screws placed from T1 to T12, 111 had diameters greater than or equal to the pedicle width. From T3 to T9, the mean diameter of the pedicle screws exceeded the mean pedicle width. Lateral pedicle wall penetration occurred significantly more often than superior, inferior, and medial pedicle wall penetrations and anterolateral vertebral body penetration. Five of six high-risk screw penetrations occurred in one patient when intraoperative technique was compromised. We observed no new postoperative neurologic deficits, visceral injuries, or pedicle screw instrumentation failures. The three high-risk anterolateral vertebral body penetrations at T1 and T2 were associated with a significantly decreased mean screw transverse angle; the three high-risk medial pedicle wall penetrations occurring from T3 to T9 were associated with a significantly increased mean screw transverse angle. Among all 26 patients available at postoperative follow-up (mean 11.9 months), the mean loss of kyphosis correction was 2.0 degree. CONCLUSIONS: Guided by intraoperative fluoroscopic imaging and anatomic landmarks, thoracic pedicle screws can be placed safely. Early clinical follow-up reveals excellent results with minimal loss of kyphosis correction.

Adult↗

PubMed2006

Inserting pedicle screws in the upper thoracic spine without the use of fluoroscopy or image guidance. Is it safe?

Several studies have looked at accuracy of thoracic pedicle screw placement using fluoroscopy, image guidance, and anatomical landmarks. To our knowledge the upper thoracic spine (T1-T6) has not been specifically studied in the context of screw insertion and placement accuracy without the use of either image guidance or fluoroscopy. Our objective was to study the accuracy of upper thoracic screw placement without the use of fluoroscopy or image guidance, and report on implant related complications. A single surgeon inserted 60 screws in 13 consecutive non-scoliotic spine patients. These were the first 60 screws placed in the high thoracic spine in our institution. The most common diagnosis in our patient population was trauma. All screws were inserted using a modified Roy-Camille technique. Post-operative axial computed tomography (CT) images were obtained for each patient and analyzed by an independent senior radiologist for placement accuracy. Implant related complications were prospectively noted. No pedicle screw misplacement was found in 61.5% of the patients. In the remaining 38.5% of patients some misplacements were noted. Fifty-three screws out of the total 60 implanted were placed correctly within all the pedicle margins. The overall pedicle screw placement accuracy was 88.3% using our modified Roy-Camille technique. Five medial and two lateral violations were noted in the seven misplaced screws. One of the seven misplaced screws was considered to be questionable in terms of pedicle perforation. No implant related complications were noted. We found that inserting pedicle screws in the upper thoracic spine based solely on anatomical landmarks was safe with an accuracy comparable to that of published studies using image-guided navigation at the thoracic level.

Adolescent↗

PubMed2001

[Computer-assisted video-endoscopic endonasal surgery].

UNLABELLED: To make the surgical procedure safer and more precise in FESS, a non-invasive markerless computer-assisted system (CAS) is described for intra-operative navigation whenever the critical regions may be affected by surgical manipulation. PATIENTS AND METHODS: Twenty patients with benign diseases of the paranasal sinuses were treated by Computer Assisted Video-endoscopic surgery, between December 1997 and March 1998. For the determination of accuracy and reproducibility of the system, ten anatomical landmarks on each side of the paranasal sinuses were chosen and measured. All of these points were identified on the direct live video-endoscopy image and compared to those obtained with the Optical Digitizing System (Flashpoint 5000(R)), on axial, coronal and sagittal view. The Optical Localizer we used detects the position of the relative coordinates of two rigid bodies made of IR-LED's each, one rigid body is secured to the head' of the patient with a headset, so that patient motion can be tracked, and the second rigid body attached to the operating instrument, leading to direct localization of the tip of the instrument. We use a markerless, skin surface-based registration method, which has the advantage to avoid doing a second CT scan examination usually performed to process the position of the fiducial markers. We register the data from the patient's usual paranasal CT scan. RESULTS: Computer-assisted surgery does not increase significantly the duration of the operation. Our markerless skin surface points registration method is reliable enabling of the movements patient's head during the procedure. Computer assistance can be used in almost any type of endoscopic sinonasal procedure. We obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% of cases. CONCLUSION: CAS enables the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Due to the passive optical technology (Passive Polaris(R)), we are continuing clinical studies in ENT surgery in order do improve the system and to simplify its current management.

Adult↗

PubMed1998

Comparison of rigid and flexible transbronchial needle aspiration in the staging of bronchogenic carcinoma.

In staging bronchogenic carcinoma by transbronchial needle aspiration (TBNA), rigid histology needles are generally preferred to flexible cytology needles owing to the widespread opinion that rigid needles have higher diagnostic yield and less false-positive results. The objective of this study was to compare the efficacy and safety of the rigid and flexible TBNAs in staging bronchogenic carcinoma to establish whether a flexible cytology needle method can replace the rigid needle. A prospective study was conducted in 138 consecutive patients with extra- or endobronchial masses suggestive of bronchogenic carcinoma and amenable to surgical procedures. All 8 mm and larger paratracheal, carinal, hilar and/or main bronchial lymph nodes determined before bronchoscopy by computed tomography (CT) were sampled by successive 18-gauge rigid and 21-gauge flexible TBNAs in the same session. The anatomic landmarks were followed precisely during TBNAs, and a proper technique applied in sampling and specimen processing. Malignant lymph node involvement was specified in 97 (72%) cases of bronchogenic carcinoma by rigid, and in 89 (66%) by flexible TBNA. There were 4 (100%) benign cases (3 with tuberculosis and 1 with sarcoidosis) of 101 (73%) with positive rigid TBNAs (82 with histological and 19 with cytological specimens). TBNAs determined malignant lymph node involvement in a total of 104 (78%) patients. Of 30 TBNA-negative patients, 14 were proven to have false-negative TBNAs by mediastinoscopy/mediastinotomy/minithoracotomy, and 16 to have true-negative TBNAs by thoracotomy. Thoracotomy confirmed true positivity in 52 rigid and 49 flexible TBNAs, and false negativity in 4 rigid and 7 flexible TBNAs. Further staging was confirmed in these 7 cases. Four had proven false-negative results by both methods. The presence of small cell carcinoma (21) or N3 disease (27) presented a contraindication to thoracotomy in 48 TBNA-positive patients. Adequate-quality and malignant lymph node specimens were more frequently obtained by both techniques at advanced tumor and node stages. However, malignant lymph node invasion was significantly more frequent in rigid and flexible TBNA specimens only in the presence of advanced tumor status and abnormal endoscopic appearance. The sensitivities of rigid and flexible TBNAs were 74 and 70%, respectively (p > 0.05), but both had a specificity of 100%. Neither false-positive results nor serious complications other than hemorrhage of 30-100 ml (rigid: 5%, flexible: 2%) were encountered with either technique. These results indicate that in bronchogenic carcinoma, hilar and mediastinal lymph nodes can be staged by 21-gauge flexible TBNA (76%) as accurately as by 18-gauge rigid TBNA (79%) if a proper technique is applied and anatomic landmarks are followed precisely (p > 0.05).

Adult↗