The use of patient specific polyetheretherketone implants for reconstruction of maxillofacial deformities.

PURPOSE: The aim of this study was to evaluate polyetheretherketone (PEEK) as a patient-specific implant (PSI) material in maxillofacial reconstructive surgery. MATERIALS AND METHODS: The retrospective study included a cohort of 24 patients who underwent maxillofacial surgery using PEEK PSIs. Each patient underwent preoperative multislice computed tomography (CT) with 0° tilt of gantry. Based on the CT scan, the PEEK PSIs were planned and manufactured using three-dimensional (3D) modeling and computer-aided design/computer-aided manufacturing (CAD/CAM) techniques. All procedures were performed under general anesthesia. Implants were placed intraorally, extraorally or through subciliary, transconjuctival or coronal incisions. RESULTS: In 22 of 24 cases, the PEEK PSI fit well without adjustments. Although the fit to the surrounding bone was perfect in almost all of the cases, the outer contour of the PSI was modified in nine cases before fixation. However, intraoperative implant modification did not affect the infection rate. In two cases, postoperative wound dehiscence and infection needed additional treatment and healed without removal of the implants. CONCLUSION: The follow-up data in this study showed good outcomes with reliable results for PSI made of PEEK in the maxillofacial region.

Tranexamic acid can inhibit tongue squamous cell carcinoma invasion in vitro.

OBJECTIVES: Tranexamic acid (TA) is an inhibitor of plasminogen activation commonly used in surgery. Plasmin, the end product of plasminogen activation, degrades fibrin in the thrombus, leading to thrombolysis. However, plasmin is also associated with progression of several cancers and with cancer-associated matrix metalloproteinase-9 (MMP-9) activation. As the gelatinases MMP-2 and -9 are involved in cancer progression, several antigelatinolytic drugs have been developed as potential anticancer therapeutics. We previously developed gelatinases targeting peptide CTT1 capable of inhibiting carcinoma growth. STUDY DESIGN: The effects of TA and CTT1 on tongue carcinoma aggressiveness were evaluated in an in vitro assay of human HSC-3 and SCC-25 cells. MATERIALS AND METHODS: The cells were cultured with or without TA and CTT1 and their proMMP-9 production and activation were analysed with Western immunoblotting and gelatin zymography. Their effects on tongue carcinoma invasion were analysed in a Matrigel assay. RESULTS: Tranexamic acid alone and in combination with CTT1 can inhibit tongue SCC invasion in vitro, at least partially explained by its property of reducing the plasmin-mediated activation of proMMP-9. CONCLUSIONS: These data suggest that patients undergoing surgical therapy for large oral malignancies may cobenefit from prolonged TA therapy, because of its antithrombolytic and antitumour properties.

Thrombus on indwelling central venous catheters: the histopathology of "Fibrin sheaths".

PURPOSE: Central venous catheters (CVC) may fail for many reasons, though "fibrin sheaths" blocking catheter ports are usually implicated. We examined the sheaths removed from dialysis catheters to determine their histopathology. METHODS: Ten catheter strippings were performed and the removed material was studied grossly and microscopically. RESULTS: The histologic specimens showed thrombus both with and without a proteinaceous sheath. CONCLUSION: Dialysis catheters fail because of thrombus formation. This can occur in either the absence or presence of a protein coating on the catheter, the so-called "fibrin sheath."

Complete MR angiography and Doppler ultrasound as the sole imaging modalities prior to carotid endarterectomy.

OBJECTIVE: To assess the combination of duplex Doppler ultrasound (DUS) and complete carotid magnetic resonance angiography (MRA) for the non-invasive imaging of carotid disease and their effect on outcomes. Determine inter-reader agreement of carotid MRA. MATERIALS AND METHODS: One-hundred and ten carotid bifurcations were evaluated using DUS, 2D and 3D time-of-flight MRA from the aortic arch to the Circle of Willis in 55 patients. Percentage stenoses were determined by two blinded readers using standardized criteria. Clinical follow-up was by chart review. RESULTS: Correlation of Doppler and MRA was excellent (r=0.903, P<0.001). Inter-reader agreement (K) for MRA was good: internal carotid artery (ICA) (0.750), external carotid artery (ECA) (0.674) and common carotid artery (CCA) (0.410). Differences in CCA readings were due to minor differences in categorizing lesions as CCA versus ICA or ECA. MRA and Doppler detected nine occluded ICAs. Two DUS occlusions had ICA flow by MRA; one due to a reconstituted precavernous ICA, one a near occluded vessel. Five patients (9%) had surgical management modified by MRA with four not having surgery: three distal ICA/Siphon occlusions and one less severe stenosis by MRA. One tandem lesion not visualized by DUS was surgically significant. Nine aortic arch abnormalities had no surgical impact, possibly due to small sample size. Of 41 endarterectomies, there were no complications from errors of diagnosis. CONCLUSION: Carotid MRA correlates well with DUS with good inter-reader agreement. MRA confirms Doppler findings, expands anatomical information and identifies tandem lesions from the aortic arch to the Circle of Willis which can affect surgical management. This approach to carotid artery imaging appears to have no negative effect on surgical outcome.

Transfemoral repositioning of malpositioned central venous catheters.

PURPOSE: To determine the efficacy of the transfemoral vein approach to repositioning malpositioned central venous catheters. METHODS: During a 4(1/2)-year period, malpositioned central venous catheters were repositioned 91 times in 83 patients via the transfemoral vein approach. All repositioning was initially attempted with a Grollman catheter or other pigtail catheter and a tip-deflecting wire. If these techniques failed or the venous anatomy was unfavorable, gooseneck or long loop snares were used. RESULTS: During 48 repositionings, rotating a pigtail-type catheter alone was used successfully in 39 (81%). In 6 of 9 failures, the addition of a tip-deflecting wire also failed. A Grollman catheter and tip-deflecting wire were used initially in 39 repositionings (6 failures; 85% success). Successful repositioning required a snare in 8 (4 as the primary repositioning technique) and a long-loop technique in 5. All repositionings were ultimately successful and there were no complications. CONCLUSION: Central venous catheters can be repositioned consistently by the transfemoral route. Pigtail catheters or tip-deflecting wires alone are successful in over 80% of cases.

Comparison of dynamic and spiral CT for imaging the glottic larynx.

OBJECTIVE: Our goal was to prospectively compare dynamic CT (DCT) and spiral CT (SCT) for evaluating patients with suspected abnormalities of the glottic region and correlate the observed differences between the two techniques with phantom measurements. MATERIALS AND METHODS: Thirty-one patients suspected of having laryngeal abnormalities underwent DCT and SCT. The studies were evaluated by two head and neck radiologists for lesion detection, visualization of the paraglottic fat planes (PGFPs), motion artifact, respiratory misregistration, and overall image quality. Slice sensitivity profile (SSP) and image noise were measured for DCT and SCT for the imaging parameters used in this study. RESULTS: Artifacts due to motion and respiratory misregistration were reduced with SCT compared with DCT. Laryngeal abnormalities and the adjacent PGFPs were better visualized with DCT than SCT. With use of similar imaging parameters, SSP and image noise were both increased with SCT compared with DCT. CONCLUSION: SCT produces high quality images of the larynx with less motion and respiratory misregistration artifacts than DCT. DCT allows better visualization of lesions and subtle anatomic features of the glottic region. SCT may substitute for DCT in laryngeal imaging.

Cocaine-induced changes in time course of regional cerebral blood volume and transit time as determined by dynamic MR imaging.

We examined cocaine-mediated change in regional cerebral blood volume (rCBV) and mean transit time (MTT) in central brain structures of rats using functional MR imaging techniques. Changes in MTT and rCBV in animals who had previously been given cocaine depended on the length of time between the last pretreatment injection and the acute injection and seemed to parallel cocaine-mediated changes in extracellular dopamine concentrations.

MR imaging of myxopapillary ependymoma: findings and value to determine extent of tumor and its relation to intraspinal structures.

OBJECTIVE: Myxopapillary ependymomas are highly vascular tumors that arise almost exclusively in the thoracolumbar region and produce symptoms that may mimic discogenic pathology. The purpose of our study was to define the typical MR features of myxopapillary ependymoma and to determine the value of MR imaging in identifying the tumor, establishing its extent, and defining its relationship to intraspinal structures. MATERIALS AND METHODS: MR studies performed on 20 patients (13 men and seven women; mean age, 35 years) with 24 pathologically proven myxopapillary ependymomas were evaluated retrospectively for size and location of lesions, expansion of the central spinal canal and neural foramina, and MR signal characteristics and enhancement patterns. T1-weighted (16 patients), proton density-weighted (15 patients), T2-weighted (14 patients), and enhanced T1-weighted (nine patients) sequences were examined. RESULTS: In all patients, masses were detected on MR images. MR imaging defined solitary masses in 17 patients and multiple lesions in three. Of the 24 tumors, MR imaging characterized 21 as predominately intradural extramedullary, two as intramedullary and intradural extramedullary, and one as extradural postsacral. Two lesions had associated syrinxes. Lesions occurred most often at the level of the L2 vertebral body, and no tumor extended above T9. Tumors spanned an average of four vertebral segments. MR imaging showed expansion of the spinal canal in five of eight tumors that extended over five or more vertebral segments. Two tumors extended into the neural foramina. The T1-weighted signal of the tumor was isointense in 12 patients, hypointense in three patients, and hyperintense in one patient. The T2-weighted signal was always hyperintense. All tumors imaged after administration of IV contrast material showed enhancement. CONCLUSION: MR imaging was valuable in identifying the extent of tumors and in defining their relationship to the intraspinal structures. Although the MR findings in myxopapillary ependymoma are nonspecific, the diagnosis can be suggested by a large, intensely enhancing, intradural extramedullary thoracolumbar mass that extends for several vertebral levels. Imaging protocols should examine the entire thoracolumbar region and include IV contrast.

Computed tomography of hamartoma of the epiglottis.

We present the computed tomography (CT) findings of a hamartoma of the epiglottis occurring in a 58-year-old man. Although hamartomas are particularly uncommon in this site. CT identification of fat within the complex mass facilitated diagnosis without recourse to an invasive biopsy.

Pre-operative imaging of esthesioneuroblastoma.

The pre-operative images of three patients with biopsy proven esthesioneuroblastoma are presented. The role of computed tomography (CT) and magnetic resonance imaging (MRI) in the pre-operative determination of tumour extent is discussed.

Osteosarcoma of the hard palate.

We present the appearances of a primary osteosarcoma of the maxilla in a 26-year-old man. The role of computed tomography--specifically, sagittal and 3-D reconstructions--and the differential diagnosis of bone lesions occurring at this site are discussed.

Spiral CT scanning of the paranasal sinuses.

Because of the interest in reducing the time and radiation required for screening sinuses with CT, we compared the quality of conventional coronal CT images with coronally reconstructed, axially acquired spiral CT images. The spiral reconstructions compared favorably with the conventional images and had significantly less motion and dental amalgam artifacts.

Comparison of spiral CT and conventional CT in 3D visualization of facial trauma: work in progress.

Spiral computed tomography (SCT) differs from conventional CT (CCT) in that regions of the body can be rapidly imaged via continuous scanning. This is accompanied by simultaneous advancement of the patient, thus allowing volumetric data acquisition of up to 60 cm in less than a minute. Thus motion is minimized and slice misregistration is minimized when multiplanar and three dimensional reconstructions are performed. This paper compares the utility of SCT and CCT in facial trauma. A total of six patients were studied with either CCT or SCT of the face after trauma. SCT scans were obtained using a Siemens Somatom Plus-S CT scanner (2 mm thick collimation and 3 mm/sec table feed for 32 s). Three-dimensional (3D) and multiplanar reconstruction images of the facial bones were generated after appropriate thresholds were selected by the radiologist; similar images generated with a CCT (GE quick 9800) were compared using a three point scale with kappa analysis. SCT is able to generate axial and reformatted images of comparable quality to CCT (k = 0.47-0.89) in less than half the time to perform an examination (26 min vs 63 min). SCT can rapidly produce (3D) and multiplanar reformatted images of facial trauma with minimal motion, or misregistration artifact when compared to CCT.

Reversible visual deficit following debulking of a Rathke's cleft cyst: a tethered chiasm?

Delayed chiasmal syndromes after emptying of a Rathke's cleft cyst have not been reported previously. When these deficits occur following the treatment of parasellar lesions they are usually associated with the descent of a scarred optic system into an empty sella, and vision often improves promptly when the optic system is elevated. Two months after transsphenoidal surgery with emptying of a large intrasellar cyst, a 22-year-old man developed recurrent bitemporal visual field deficits over a 3-day period. Sagittal magnetic resonance images demonstrated an enhancing band of tissue extending anteriorly from the normally placed chiasm down to the anterior portion of the sella turcica. At craniotomy the enhancing tissue was found to be scar extending from the anterior border of the chiasm to the diaphragma sellae. The anterior portion of the diaphragm was resected as widely as possible without dissecting the scar itself from the chiasm. A membrane consistent with the wall of a Rathke's cleft cyst was found attached to the resected tissue. The patient's vision was improved 2 days after surgery. This case illustrates that traction by scar extending from the chiasm to the diaphragm, even when the chiasm is in its normal anatomical location, may cause progressive visual loss; and that untethering of the chiasm by resecting the diaphragm while leaving the scar intact can result in improved vision.

Spiral CT of the larynx.

PURPOSE: To compare conventional and spiral CT studies of the larynx. METHODS: Ten patients had both conventional and spiral CT studies of the neck using 5-mm section collimation and 5-mm increments. The spiral scans also were reconstructed at 2-mm increments. Five patients had two spiral CT larynx studies with 5-mm and 2-mm collimation. Two observers independently rated the visibility of laryngeal structures and absence of motion artifact in the studies and assigned values from 1 (poor) to 4 (excellent). RESULTS: The spiral scan images showed less motion artifact (1.9 versus 3.6) and better anatomic detail (2.3 versus approximately 2.6). Thinner reconstruction intervals and sections gave better anatomic detail (2.3 versus approximately 3.3). Interobserver kappa was 0.65. CONCLUSION: Spiral is better than conventional CT scanning when studying the larynx.

Spontaneous calcific embolization to the supraclinoid internal carotid artery from a regurgitant bicuspid aortic valve.

Calcific brain embolization leading to stroke is rarely recognized. We report a case of spontaneous embolization to the right cerebral circulation from a severely regurgitant, calcified bicuspid valve. Bicuspid aortic valves constitute the most common congenital heart abnormality, and have a tendency to become stenosed, regurgitant, calcified, or infected. The presence of heavy calcification in a noninfected bicuspid valve may lead to dislodgement of calcific embolic material which is not necessarily heralded by acute valvular rupture. Accurate localization of the calcific embolus to the right supraclinoid internal carotid artery was provided by spiral CT imaging in this case.

Spiral CT in evaluation of head and neck lesions: work in progress.

Spiral computed tomography (CT) was used in the evaluation of 21 patients with head and neck lesions. Scanning time ranged from 24 to 36 seconds, and high-quality diagnostic scans with excellent anatomic resolution and minimal motion artifact were produced. Vascular opacification was optimized with substantially less contrast medium than used in conventional studies. These preliminary results show spiral CT to be at least comparable with conventional CT in the evaluation of the head and neck.

Cocaine- and methamphetamine-induced acute cerebral vasospasm: an angiographic study in rabbits.

Stroke is a frequently reported, though uncommon, complication of drug abuse, primarily cocaine. The pathogenesis is uncertain, although such cerebrovascular events may result from sympathetically mediated vasoconstriction of cerebral vessels. Amphetamine, another sympathomimetic amine that is commonly abused, may also cause strokes by producing cerebral vasospasm and/or vasculitis. Amphetamine and its derivatives are frequent adulterants of illegally obtained cocaine and may also be used concurrently; the effect(s) of this combination of drugs upon the cerebral vasculature is not known. Our aim was to develop an animal model that would enable us to study the ability of these drugs to produce acute cerebral vasospasm and to observe the response to IV administration of amphetamine and cocaine, either alone or together. Magnified basilar artery arteriograms were obtained in 12 New Zealand white rabbits before and after IV administration of cocaine, methamphetamine, or both, at various dosages. Low doses produced mild vasodilatation. At higher doses, the animals who received cocaine and methamphetamine alone showed little or no basilar artery spasm, but coadministration produced definite basilar artery vasospasm, reflecting a synergistic vasoconstrictive effect. If a similar response exists in the human cerebral vasculature, then this could help explain the cause of strokes associated with drug abuse.