Spatial and temporal registration of CT and SPECT images: development and validation of a technique for in vivo three-dimensional semiquantitative analysis of bone.

UNLABELLED: The combined use of postoperative 3-dimensional CT and SPECT imaging provides a means of relating anatomy and physiology for the semiquantitative in vivo analysis of bone. This study focuses on the development and validation of a technique that accomplishes this through the registration of SPECT data to a 3-dimensional volume of interest (VOI) interactively defined on CT images. METHODS: Five human cadaver heads served as anthropomorphic models for all experiments. Four cranial defects were created in each specimen with inlay and onlay split-skull bone grafts reconstructed to skull and malar recipient sites. To acquire all images, each specimen was landmarked with 1.6-mm ball bearings and CT scanned. Bone surfaces were coated with 99mTc-doped paint. The locations of the ball bearings were marked with paint doped with 111In. Separate SPECT scans were acquired using the energy windows of 99mTc and 111In. RESULTS: Serial SPECT images aligned with an average root-mean-square (RMS) error of 3.8 mm (i.e., <1 pixel). CT-to-SPECT volume matching aligned with an RMS error of 7.8 mm. Total counts in CT-defined VOIs applied to SPECT data showed a strong linear correlation (r2 = 0.86) with true counts obtained from a dose calibrator. CONCLUSION: The capability of this multimodality registration technique to anatomically localize and quantify radiotracer uptake is sufficiently accurate to warrant further assessment in an in vivo trial.

Comparison of laser Doppler flowmeter and radioactive microspheres in measuring blood flow in pig skin flaps.

Laser Doppler flowmetry is a noninvasive technique commonly used to monitor skin perfusion after free-tissue transfer or replantation in reconstructive surgery. Several investigators have expressed concern about the reliability of the quantitative value provided by laser Doppler flowmeters (LDF) and the extent to which they reflect nutrient blood flow. This experiment was designed to compare quantitatively the skin blood flow in the pig measured by LDF and by 15-micron radioactive microspheres (RMs). It was observed that the skin blood flow rates measured by LDF and RMs in the normal skin and in acute random-pattern and arterialized skin flaps were highly correlated (r = 0.93, P < .01). However, the skin blood flow rates measured by LDF were consistently higher (P < or = .05) than the corresponding flow rates measured by RMs, and this discrepancy increased considerably at low skin blood flow rates (< 2 mL/min/100 g). We speculated that the LDF most likely measured both nutrient and arteriovenous shunt flow in the skin and that this arteriovenous shunt flow at least in part caused the discrepancy in skin blood flow rates measured by the LDF and RMs because the 15-micron RMs are known to measure nutrient blood flow only. The inherent variations and errors in LDF technique were also discussed.

Three-dimensional facial anthropometry using a laser surface scanner: validation of the technique.

Three-dimensional measurement and characterization of facial surface anatomy are fundamental to the objective analysis of facial deformity. However, existing clinical tools are inadequate. Recent innovations in laser scanning technology provide a potentially useful technique for accurate three-dimensional documentation of the face. The purpose of this study is to evaluate the reliability of interactive anthropometric landmark localization based on digitized three-dimensional facial images and to identify sources of error associated with the technique. Three-dimensional surface data were acquired using a commercially available laser scanning device (Cyberware 3030RGB digitizer), and all subsequent anthropometric analyses were performed interactively on the computer monitor. Four experimental conditions were studied, with 10 observations for each condition. A stable anthropomorphic model with prelabeled anatomic landmarks was scanned repeatedly under varying conditions of head inclination and position within the scanning gantry to determine the effect of these variables on the reliability of the technique. The scanning protocol was then repeated with the labels removed to evaluate the reliability of interactive localization of anthropometric landmarks on a digitized three-dimensional image. Optimal results were obtained with the head positioned in the center of the scanning gantry and with the Frankfort plane elevated 10 degrees from the horizontal. Under these circumstances, all 22 labeled landmarks were visualized and the variance in landmark localization was less than 0.6 mm in the x (horizontal), y (vertical), and z (depth) dimensions. Varying head position or inclination caused significant degradation of the digitized image. The variance of interactive landmark localization was analyzed in three dimensions. The reliability and the spatial orientation of variability were determined for each anthropometric point. These findings have direct implications for the clinical adaptation of this diagnostic tool for quantitative evaluation of facial surface anatomy.

Controlled bending of cranial bone grafts: a simple surgical technique.

The cranium serves as a primary bone graft donor site in reconstructive craniofacial surgery. However, the mechanical properties of cranial bone predispose to fragmentation when excessive bending forces are applied, or to a return to the original shape when bending forces are insufficient. The precise and sustained contouring of cranial bone therefore remains a practical clinical problem. This paper describes a simple surgical technique which relies upon the application of a miniplate to the cortical surface of the cranial bone segment prior to bending. The miniplate serves to reinforce the segment, allowing accurate shaping of cranial bone and maintenance of the newly acquired contour.

The effects of temporalis muscle manipulation on skull growth: an experimental study.

Craniofacial reconstructive procedures are frequently associated with some dissection or transposition of the temporalis muscle. During active growth, such muscle manipulations may influence craniofacial development. The purpose of this study was to determine the effects of surgical manipulation of the temporalis muscle on craniofacial skeletal growth and morphology. Twenty-five New Zealand White rabbits underwent temporalis muscle surgery at 6 weeks of age. Group I (n = 6) underwent a sham procedure and served as a control group. Group II (n = 6) underwent simple elevation of the left temporalis muscle and immediate reapproximation. Group III (n = 7) underwent complete transection of the left temporalis muscle. Group IV (n = 6) underwent elevation of the left temporalis muscle and transposition to the left zygoma. Growth alterations were evaluated by standardized cephalometric x-rays. Baseline anteroposterior skull x-rays were performed preoperatively and every 3 weeks for the duration of the study. The study was terminated at 24 weeks of age. At this point, dry skull preparations were analyzed quantitatively by direct cephalometric evaluation. Manipulations of the temporalis muscle produce changes in local skull morphology and affect craniofacial growth. Skull length increases when the action of the temporalis muscle is interrupted either transiently or permanently, while skull width decreases. Temporalis muscle transposition to the orbit resulted in altered orbital dimensions. Qualitative analysis of local skull morphology further revealed posterior displacement of the external auditory meatus, a depressed temporalis fossa, and multiple resorption cavities following elevation of the temporalis muscle.

Growth potential in suture bone inlay grafts: a comparison of vascularized and free calvarial bone grafts.

The present study investigates transsutural growth in vascularized and free calvarial bone grafts and notes the effects of such growth on craniofacial development. The temporalis myoosseous flap served as a model of vascularized graft. In ten 8-week-old dogs, a standardized skeletal defect, including a segment of the zygomatico-maxillary suture, was created. The defect was reconstructed with a vascularized graft in half the animals and a corresponding free graft in the remaining animals. Growth was assessed by means of serial cephalometric radiography and direct osteometry. Vascularized bone grafts demonstrated persistent transsutural growth following transplantation. Growth at the recipient site was preserved, resulting in less restriction of vertical maxillary development.

Growth potential in onlay bone grafts: a comparison of vascularized and free calvarial bone and suture bone grafts.

Vascularized bone grafts are characterized by a viable cell population with osteogenic potential. These features suggest that continued growth can be anticipated following vascularized membranous bone transfer in a growing craniofacial skeleton. The present paper compares the potential for appositional bone growth in vascularized and free calvarial onlay bone grafts. In seven 8-week-old beagles, growth was assessed by direct caliper measurements of graft dimensions intraoperatively and 16 weeks postoperatively. Vascularized grafts demonstrated a 50 to 60 percent increase in size in all dimensions compared to 10 to 20 percent growth in free grafts (p less than 0.01). Microradiography revealed preservation of calvarial bony architecture and minimal resorption in vascularized grafts, while triple-fluorochrome labeling confirmed subperiosteal appositional bone formation. Free grafts were characterized by significant resorption and a delay in subperiosteal bone formation.

Cranioplasty: indications, technique, and early results of autogenous split skull cranial vault reconstruction.

Since 1990, fresh autogenous split skull cranioplasty has been the preferred method of reconstructing complicated cranial defects at the Sunnybrook Hospital. Eight cases of split skull cranioplasties were reviewed to illustrate the indications and technical considerations of the procedure. Clinical factors believed to be detrimental to the outcome of split skull cranioplasty were identified by: 1) a history of an infected, failed, previous cranial reconstruction, 2) inadequate scalp or skin to cover the external surface of an anticipated skeletal vault reconstruction, 3) the communication of adjacent paranasal sinuses with the epidural space, 4) the presence of an avascular dead space posterior to the reconstructed cranium. These potentially negative influences were systematically addressed as part of the surgical routine in autogenous split skull cranioplasty.

Early definitive bone and soft-tissue reconstruction of major gunshot wounds of the face.

The use of craniofacial surgical techniques, extended open reduction, rigid fixation with plates and screws, and the replacement of severely damaged or missing bone with immediate bone grafting in the treatment of complex facial fractures has been applied to the management of severe gunshot wounds of the face. Early definitive bone and soft-tissue reconstruction has been performed in 37 patients. One-hundred and seventy-seven primary bone grafts were utilized in 33 patients for orbital, nasal, zygomatic, and maxillary reconstruction. Twenty-six patients required mandibular repair with compression or reconstruction plates. Soft-tissue reconstruction was provided by a combination of flaps. Four patients had extensive soft-tissue loss replaced by free vascularized omental flaps. The omentum provided circumferential coverage of the mandibular reconstruction and reconstruction of the floor of the mouth and was then tunneled in a circle through both cheeks into the middle and upper face. The omentum reconstructed deficits in the hard palate and upper buccal sulcus and was then wrapped around all zygomatic, orbital, and midfacial bone grafts and used to fill in dead space in the maxillary, ethmoid, and frontal sinuses. The omentum is not used to provide contour and bulk, but to cover bone grafts and plates and fill in dead space. Carefully shaped bone grafts provide the correct craniofacial scaffold. Early restoration of a midfacial bony scaffold and the prevention of soft-tissue contraction facilitate secondary reconstruction. Four late total nasal reconstructions with tissue-expanded forehead skin wrapped around bone grafts were performed.

Blow-in fractures of the orbit.

A blow-in fracture is an inwardly displaced fracture of the orbital rim or wall resulting in decreased orbital volume. The purpose of this study is to classify orbital blow-in fractures, describe the distinguishing clinical and radiologic features, and review the result of treatment. The series consists of 41 patients with blow-in fractures (34 males and 7 females). The mean age of the patients was 36 years. All were treated between 1979 and December of 1986 at Sunnybrook Medical Centre in Toronto. Clinical features of blow-in fractures were primarily related to the decrease in volume of the orbital cavity. Proptosis was a consistent finding, and in 27 percent of patients, the globe was further displaced in a coronal plane. Restricted ocular motility and diplopia were documented in 24 and 32 percent of patients, respectively. Fracture fragments displaced into the orbit resulted in globe rupture in 12 percent of patients, superior orbital fissure syndrome in 10 percent, and optic nerve injury in 1 patient. Blow-in orbital injuries were classified as pure fractures, consisting of an isolated blow-in of a segment of the roof, floor, or walls, or impure fractures, where the orbital rim itself was disrupted. In all cases, early decompression of the orbit and open reduction of fractures was necessary. Late sequelae of blow-in fractures were primarily related to injuries of intraorbital contents. Twelve percent of patients underwent enucleation and 8 percent reported persistent diplopia. Despite the presence of superior orbital fissure syndrome and complete ophthalmoplegia in 10 percent of patients, early orbital decompression resulted in resolution of nerve palsies in all but one patient.

Facial asymmetry: three-dimensional analysis using laser surface scanning.

This study evaluates six different techniques with respect to their ability to quantitatively describe facial asymmetry in three dimensions. Three-dimensional facial images were acquired using a Cyberware 3030RGB laser surface scanner. Image processing was performed on a Silicon Graphics Indigo computer workstation. The following techniques for facial asymmetry analysis were developed: asymmetry in the location of anthropometric landmarks, Euclidean distance matrix analysis (EDMA), scalar measurement of the lower ciliary margin and palpebral fissure area, clearance vector mapping, and determination of the volume of asymmetry. Techniques were applied and validated in three anthropometric models: a perfectly symmetrical plastic head model and a plaster head model with and without a unilateral cheek augmentation. In each of the anthropometric test models, each analytical technique was validated by means of static anthropometric facial models and was evaluated for intraobserver and interobserver reliability. Asymmetries in the location of anthropometric landmarks can be accurately determined to within 2 mm in x, y, and z directions of the Cartesian space. EDMA is a useful technique in describing both size and shape changes of discrete areas of the face. Measurement of the lower ciliary margin and palpebral fissure area is reliable. Clearance vector mapping is especially useful in quantifying facial surface asymmetries in facial areas where anthropometric landmarks are scarce. Volume of asymmetry is potentially useful in those patients for whom the use of injections or implants of known volume may be helpful in correcting unilateral facial deficiencies.

Tissue expansion in head and neck reconstruction.

The present study reviews our clinical experience with tissue expansion in head and neck reconstruction. The clinical series consists of 33 expansions performed in 29 patients between 1983 and 1986. The results of tissue expansion in the head and neck were distinguished by a high complication rate, necessitating some revision in the original treatment plan in 48 percent of patients. Despite this high incidence of complications, sufficient tissue was generated to successfully complete the planned reconstruction in 79 percent of patients. Specific complications were observed with particularly high frequency within distinct anatomic sites. The highest incidence of complications occurred in the cheek and neck (69 percent) and forehead (50 percent) regions. Complications in the eyelid region (33 percent) and scalp (17 percent) were less common. Implant exposure was the most frequently observed complication. Other sequelae noted in this series included intractable pain, infection, and bone resorption.

Use of a new anchoring device for tendon reinsertion in medial canthopexy.

This paper describes the use of the Mitek Mini GII Anchor System for tendon reinsertion in medial canthopexy. The system is simple, fast to insert, and easy to use. It allows precise placement with minimal dissection, which is limited to the ipsilateral orbit.

The importance of the zygomatic arch in complex midfacial fracture repair and correction of posttraumatic orbitozygomatic deformities.

Collapse of the zygomatic arch following trauma results in inadequate anteroposterior projection of the zygomatic body and an increase in facial width. Accurate assessment of the position of the zygomatic arch in relation to the cranial base posteriorly and the midface anteriorly is the key to the acute repair of complex midfacial fractures and the secondary reconstruction of posttraumatic deformities of the orbitozygomaticomaxillary complex. Loss of projection of the zygomatic arch may occur with injuries confined to the orbitozygomaticomaxillary region or in association with complex midfacial fractures. A safe anatomic approach to the zygomatic arch allows exact anatomic restoration of the zygomatic arch using miniplates and screws and results in the reconstruction of an outer facial frame with a correct anteroposterior projection and facial width. The zygomatic arch injury is diagnosed using axial CT scanning. Three-hundred and seventeen arches have been exposed through a coronal incision following acute trauma and 47 arches have been exposed in patients requiring late correction of a posttraumatic orbitozygomaticomaxillary deformity. Permanent palsy to the frontal branch of the facial nerve has occurred in one patient following the exact definition of the anatomy of this region.

The temporalis myo-osseous flap: an experimental study.

The present paper investigates the anatomy and vascularization of the temporalis myo-osseous flap. This is a calvarial bone flap that employs temporalis muscle and its distal pericranial extension as a pedicle. In six human cadavers the flap was raised as an island on the anterior deep temporal artery after transecting the zygomatic arch and coronoid process. Maximal mobilization was thus obtained, allowing rotation of the flap into the mouth for intraoral reconstruction. The arc of rotation and potential surgical applications were noted. A comparative study of the temporalis myo-osseous flap and free calvarial bone graft was then conducted in a rabbit model. Vascularization of the calvarial bone flap was confirmed by technetium scintigraphy performed on the first postoperative day. The uptake of fluorochrome labels immediately after transfer verified the adequacy of the periosteal circulation in maintaining viability and new osteoid formation throughout the full thickness of calvarial bone. The transplantation of free calvarial bone grafts was followed by necrosis of most cellular elements. This was demonstrated by an absence of fluorochrome uptake up to 19 days postoperatively and a predominance of empty lacunae and nonviable marrow.

Arteriovenous fistulas after replantation surgery.

The delayed appearance of congenital arteriovenous fistula precipitated by local trauma is a rare event. However, these reports may provide some insight into pathogenetic mechanisms responsible for the opening of subclinical arteriovenous communications. This case of multiple arteriovenous fistulas in a previously "normal" hand followed a sharp, incomplete amputation at the wrist level with replantation.

Extramammary Paget disease: review of patients seen in a non-melanoma skin cancer clinic.

Extramammary Paget disease (EMPD) is a rare skin disease commonly found in the anogenital region. In this study, we aimed to identify EMPD patients seen in the non-melanoma skin cancer clinic at Odette Cancer Centre and to describe the treatments delivered and outcomes achieved. From 2000 to 2009, 14 patients were seen. Initial treatment recommendations included imiquimod and surgical excision, although half the patients required more than one treatment modality, highlighting the difficulty of achieving complete eradication of this disease.

Advanced technology in the management of fibrous dysplasia.

BACKGROUND: The aim of this paper is to describe the applications of advanced imaging technology in optimising the surgical management of complex craniofacial fibrous dysplasia (FD). METHODS: Preoperative planning involved a number of advanced technologies. Haptic modelling was used to simulate tumour excision and the design of the osteotomies, on a virtual 3D computerised tomographic (CT) scan. Rapid prototyping was employed in fabricating a physical prototype of the skull, featuring the ideal, symmetrical reconstruction. Tumour extirpation was carried out with the aid of stereotactic navigation. Intraoperatively, resorbable mesh is moulded precisely to the shape of the skull prototype, thereby transferring the surgical simulation to the patient in the operating room. The resorbable mesh serves as a template which guides the shape and spatial orientation of an autologous bone graft reconstruction. Pre- and postoperative volumetric differences were assessed to determine the accuracy of the final results. RESULTS: Short and long term follow-up examinations show excellent cosmetic outcome, with significant restoration of volumetric symmetry. CONCLUSIONS: The added complexity of using the new technologies increases preoperative planning time, but we believe that this is offset by the improved safety during the resection of the tumours as well as the excellent aesthetic outcomes.

Soft tissue deformity after craniofacial fracture repair: analysis and treatment.

BACKGROUND AND OBJECTIVES: The primary repair of facial fractures requires sufficient subperiosteal dissection and mobilization of soft tissues to permit accurate fracture reduction. Improper repositioning of soft tissues predisposes the site to deformities with subsequent adverse effects on the aesthetics of the final result. The purpose of this paper is to describe these deformities, the modification of surgical approaches to avoid them, and the various techniques for secondary soft tissue reconstruction. METHODS AND MATERIALS: The paper reviews the assessment of soft tissue deformity and the principles of soft tissue reconstruction in addressing temporal contour deformity, cheek ptosis, eyelid deformities, and medial and lateral canthal dystopia. RESULTS AND/OR CONCLUSIONS: The morbidity of remote incisions and soft tissue degloving used in primary facial fracture repair can be minimized by using a meticulous technique and precise soft tissue repositioning at closing.

Use of porous high-density polyethylene implants in temporal contour reconstruction.

A temporal contour deformity is characterized by a concavity or depression in the soft-tissue contour of the temporal region and is associated with exaggerated relief of the lateral orbital rim and the zygomatic arch. The etiology of the deformity is varied, comprising any condition that results in displacement, atrophy, or absence of the temporalis muscle or the superficial temporal fat pad. We describe reconstruction of this deformity with porous high-density polyethylene implants in 16 consecutive patients, treated between July 1988 and September 1990. The etiology of the deformity and the surgical treatment are described. The results of treatment are assessed on long-term follow-up, ranging from 2 to 4 years postoperatively.