[Imaging of the Inner Ear Before Cochlear Implantation]. / Bildgebende Diagnostik des Innenohrs vor Cochleaimplantation.

If sufficient speech understanding can no longer be achieved with conventional hearing aids, the indication for a cochlear implant is very often present. Imaging plays an important preoperative role, as it is the only way to decide whether a cochlear implant is possible or not. The preoperative evaluation of the temporal bone for the precise selection of the candidates for cochlear implant is including CT (Computed Tomography) and MRI (Magnetic Resonance Imaging).

[Facet infiltration and periradicular therapy]. / Facetteninfiltration und periradikuläre Therapie.

BACKGROUND: Spinal complaints affect a large proportion of the population and lead to numerous doctor visits. PURPOSE: The different techniques of CT-guided infiltration of spinal disorders, taking into account facet infiltration, periradicular infiltration and epidural flooding are demonstrated. MATERIALS AND METHODS: Discussion of basic work and expert recommendations as well as presentation of different treatment steps for everyday clinical practice. RESULTS: The CT-guided application of the different types of infiltration allows precise execution of the therapy. Both facet infiltration and periradicular infiltration and epidural flooding have their place depending on the clinical symptoms. The optimal combination of drugs to administer is still the subject of numerous studies and sometimes controversial discussions. CONCLUSION: An exact clinical and imaging evaluation of the pain symptoms in the back is the basic requirement for a targeted therapy.

Percutaneous cannulated screw fixation of sacral fractures and sacroiliac joint disruptions with CT-controlled guidewires performed by interventionalists: single center experience in treating posterior pelvic instability.

OBJECTIVE: The purpose of our study was to evaluate minimally invasive sacroiliac screw fixation for treatment of posterior pelvic instability with the help of CT controlled guidewires, assess its accuracy, safety and effectiveness, and discuss potential pitfalls. METHODS: 100 guidewires and hollow titan screws were inserted in 38 patients (49.6±19.5 years) suffering from 35 sacral fractures and/or 16 sacroiliac joint disruptions due to 33 (poly-)traumatic, 2 osteoporotic and 1 post-infectious conditions. The guidewire and screw positions were analyzed in multiplanar reconstructions. RESULTS: The mean minimal distance between guidewire and adjacent neural foramina was 4.5±2.01mm, with a distinctly higher precision in S1 than S2. Eight guidewires showed cortical contacts, resulting in a total of 2% mismatched screws with subsequent wall violation. The fracture gaps were reduced from 3.6±0.53mm to 1.2±0.54mm. During follow-up 3 cases of minor iatrogenic sacral impaction (<5mm) due to the bolting and 2 cases of screw loosening were observed. Interventional time was 84.0min with a mean of 2.63 screws per patient whilst acquiring a mean of 93.7 interventional CT-images (DLP 336.7mGycm). CONCLUSIONS: The treatment of posterior pelvic instability with a guidewire-based screw insertion technique under CT-imaging results in a very high accuracy and efficacy with a low complication rate. Careful attention should be drawn to radiation levels.

Multidetector computed tomography (MDCT): simple CT protocol for trauma patient.

The purpose of this retrospective monocenter study was to evaluate a monophasic multidetector computed tomography (MDCT) protocol with a fixed delay for patients with polytrauma. A total of 2086 patients were evaluated retrospectively. For the intravenous contrast media, we used a fixed protocol with an injection for an adult patient of 120 mL at a rate of 2 mL/s. In the venous phase, we detected injuries of parenchyma and localized ongoing bleedings in regard to the clinical follow-up, with regard to the easy feasibility and the quickness with only one scan. Monophasic venous injection protocol can detect all injuries in the whole-body MDCT for patients with polytrauma.

Outcome of long-axis percutaneous sacroplasty for the treatment of sacral insufficiency fractures with a radiofrequency-induced, high-viscosity bone cement.

Our goal was to assess the technical results in patients who underwent long-axis sacroplasty for the treatment of sacral insufficiency fractures (SIF) by radiofrequency-induced high-viscosity bone cement augmentation. Twelve patients with bilateral sacral fractures were treated by augmentation with radiofrequency-activated, high-viscosity polymethylmethacrylate (PMMA) bone cement under local anesthesia. CT-guided sacroplasty was performed by using a long-axis approach through a single entry point. Thirty-six vertebrae were treated in 12 sessions under a combination of CT and fluoroscopic guidance using a bilateral access and a cavity-creating osteotome prior to remote-controlled, hydraulically driven cement injection. The visual analogue scale (VAS) score before sacroplasty and at 1 and 3 months after the treatment was obtained. PMMA leaks were evaluated retrospectively using the post-interventional CT. The mean amount of high-viscosity PMMA injected per patient was 7.8 ml. No major adverse events were observed. In the first 4 days after the procedure, the mean VAS score decreased from 8.1 ± 1.9 to mean 3.1 ± 1.2 and was followed by a gradual but continuous decrease throughout the rest of the follow-up period at 24 weeks (mean 2.2 ± 1.1) and 48 weeks (mean 2.1 ± 1.4). CT fluoroscopy-guided sacral augmentation was safe and effective in all 12 patients with osteoporotic SIF.

Evaluation of MRI T1-based treatment monitoring during laser-induced thermotherapy of liver metastases for necrotic size prediction.

PURPOSE: The aim of this study was to evaluate the accuracy of real-time magnetic resonance imaging (MRI) T1-based treatment monitoring for predicting volume of lesions induced by laser-induced thermotherapy (LITT) of liver metastases. MATERIALS AND METHODS: This prospective study was approved by the institutional review board and informed consent from all included patients was obtained. In 151 patients, 237 liver metastases were ablated during 372 LITT procedures. 1.5 T MRI treatment monitoring was performed based on longitudinal relaxation time (T1) using fast low-angle shot (FLASH) sequences. Patients underwent additional contrast-enhanced MRI directly after LITT, 24 h after the procedure and during follow-up at 3, 6 and 12 months. The amount of energy necessary to induce a defined necrotic area was investigated within the various liver segments. RESULTS: The total amount of energy applied during LITT varied from 6.12-225.32 kJ (mean 48.96 kJ). Ablation in liver segments 5 (2.12 kJ/cm(3)) and 8 (2.16 kJ/cm(3)) required the highest energy. The overall pre-ablative metastasis volume ranged from 0.5-51.94 cm(3) (mean 1.99 cm(3), SD 25.49 cm(3)) while the volume measured in the last available T1 image varied from 0.78-120 cm(3) (mean 26.25 cm(3), SD 25.66 cm(3)). Volumes measured via MRI T1-based treatment monitoring showed a stronger correlation with necrosis 24 h after LITT (r = 0.933, p < 0.001) than contrast-enhanced MRI directly after the procedure (r = 0.888, p < 0.001). CONCLUSIONS: Real-time MRI T1-based treatment monitoring during LITT of liver metastases allows for precise estimation of the resulting lesion volume and improves control of the energy necessary during ablation.

Magnetic resonance-guided laser-induced thermotherapy in patients with oligonodular hepatocellular carcinoma: long-term results over a 15-year period.

GOALS: To prospectively evaluate the therapeutic potential of magnetic resonance (MR)-guided laser-induced thermotherapy (LITT) in patients with oligonodular hepatocellular carcinoma. STUDY: A total of 113 patients with 175 intrahepatic lesions were treated with MR-guided LITT. The Nd-YAG laser fiber was introduced with a percutaneously positioned irrigated laser application system. Qualitative and quantitative MR parameters and clinical data were evaluated. Survival data were calculated using the Kaplan-Meier method. RESULTS: All patients tolerated the procedure well under local anesthesia. The total procedure time was 90 minutes. All observed complications were minor and no further treatment was necessary. Online MR thermometry allowed exact visualization of the extension of laser-induced changes and their relationship to the neighboring anatomy. Lesions up to 2 cm in diameter could be efficiently treated with a single laser application; larger lesions were treated with a dual, triple, and quadruple simultaneous application. In 98% of the patients we achieved a complete necrosis of the tumor and up to 5 mm of safety margin. The mean survival rate for all patients, with calculation started on the date of diagnosis of the HCC nodules treated with LITT, was 4.9 years (95% confidence interval, 3.6, 5.1). The median survival rate for all patients, with calculation started on the date of diagnosis of the HCC nodules treated with LITT, was 3.5 years (95% confidence interval, 2.7, 4.2). One-year survival was 95%; 2-year survival 72%, 3-year survival 54%; and 5-year survival 30%. CONCLUSIONS: In intrahepatic oligonodular involvement of hepatocellular carcinoma LITT appears to be an effective therapeutic procedure.

MR-based thermometry of laser induced thermotherapy: temperature accuracy and temporal resolution in vitro at 0.2 and 1.5 T magnetic field strengths.

PURPOSE: To evaluate MR-thermometry using fast MR sequences for laser induced interstitial thermotherapy (LITT) at 0.2 and 1.5 T systems. METHODS & MATERIALS: In-vitro experiments were performed using Agarose gel mixture and lobes of porcine liver. MR-thermometry was performed by means of longitudinal relaxation time (T1) and proton resonance frequency shift (PRF) methods under acquisition of amplitude and phase shift images. Four different sequences were used for T1 thermometry: A gradient-echo (GRE), a True Fast Imaging with Steady Precession (TRUFI), a Saturation Recovery Turbo-FLASH (SRTF), and an Inversion Recovery Turbo-FLASH (IRTF) sequence (FLASH-Fast Low Angle Shot). PRF was measured with four sequences: Two fast-spoiled GRE sequences (one as WIP sequence), a Turbo-FLASH (TFL) sequence (WIP sequence), and a multiecho-TrueFISP sequence. Temperature was controlled and verified using a fiber-optic Luxtron device. The temperature was correlated with the MR measurement. RESULTS: All sequences showed a good linear correlation R(2) = 0.97-0.99 between the measured temperature and the MR-thermometry measurements. The only exception was the TRUFI sequence in the Agarose phantom that showed a non-linear calibration curve R(2) = 0.39-0.67. At 1.5 T, the Agarose experiments revealed similar temperature accuracies of 4-6°C for all sequences excluding TRUFI. During experiments with the liver, the PRF sequences showed better performance than the T1, with accuracies of 5-12°C, contrary to the T1 sequences at 14-18°C. The accuracy of the Siemens PRF-FLASH sequence was 5.1°C. At 0.2 T, the Agarose experiments provided the highest accuracy of 3.3°C for PRF measurement. At the liver experiments the T1 sequences SRTF and FLASH revealed the best accuracies at 6.4 and 7.0°C. CONCLUSION: The accuracy and speed of MR temperature measurements are sufficient for controlling the temperature-based tumor destruction. For 0.2 T systems SRTF and FLASH sequences are recommended. For 1.5 T systems SRTF and FLASH are the most accurate.

Dual-energy CT of head and neck cancer: average weighting of low- and high-voltage acquisitions to improve lesion delineation and image quality-initial clinical experience.

OBJECTIVES: Mixing low- and high-voltage acquisitions of dual-energy CT (DECT) scan using different weighting factors leads to differences in attenuation values and image quality. The aim of this work was to evaluate whether average weighting of DECT acquisitions could improve delineation of head and neck cancer and image quality. MATERIALS AND METHODS: Among 60 consecutive patients who underwent DECT scan of the head and neck, 35 patients had positive findings and were included in the study. Images were reconstructed as pure 80 kVp, pure Sn140 kVp, and weighted-average (WA) image datasets from low- and high-voltage acquisitions using 3 different weighting factors (0.3, 0.6, 0.8) incorporating 30%, 60%, 80% from the 80 kVp data, respectively. Lesion contrast-to-noise ratio (CNR), attenuation measurements, and objective noise were compared between different image datasets. Two independent blinded radiologists subjectively rated the overall image quality of each image dataset on a 5-point grading scale comprising lesion delineation, image sharpness, and subjective noise. RESULTS: Mean venous and tumor enhancement and muscle attenuation increased stepwise with decreasing tube voltage from Sn140 kVp through 80 kVp. CNR increased significantly from Sn140 kVp to weighting factor 0.3 then to weighting factor 0.6 (P < 0.0001). The increase in CNR from weighting factor 0.6 to 0.8 then to 80 kVp was nonsignificant (P = 1.00). The 0.6 weighted-average image dataset received the best image quality score by the 2 readers. CONCLUSION: Mixing the DE data from the 80 kVp and Sn140 kVp tubes using weighting factor 0.6 (60% from 80 kVp data) could improve lesion CNR and subjective overall image quality (including lesion delineation). This weighting factor was significantly superior to the 0.3 weighting factor which simulates standard 120 kVp acquisition.

Image-quality perception as a function of dose in digital radiography.

OBJECTIVE: The purpose of this article is to determine the degree to which the skin entrance dose could be lowered, by adjusting exposure parameters and filtration, and the subsequent effect on readers' confidence levels of digital radiographs. MATERIALS AND METHODS: The study was prospectively performed on a cadaver. Digital radiographs of bones were evaluated and scored on a 9-point scale separately by four radiologists who were blinded to the types of filtration and doses used. The study entailed three phases: phase 1, random dose and filter; phase 2, fixed filter and varying radiation doses (100%, 75%, 50%, and 25% of the standard recommended dose); and phase 3, fixed dose and varying filtration (no filtration, aluminum filter, and aluminum-copper filter). Skin entrance dose was measured using a dosimeter placed on the skin. Differences in scores were tested using a Friedman test. RESULTS: The mean scores given to images with 100%, 75%, 50%, and 25% of the recommended standard dose were 6.18, 6.1, 5.11, and 4.07, respectively. No significant difference was noted between 100%- and 75%-dose images (p = 0.1). A significant difference (p < 0.0001) was noted when we compared the 100%- and 75%-dose images with the 50%- and 25%-dose images. The mean scores given for no filtration, aluminum filtration, and aluminum-copper filtration were 5.67, 5.43, and 5.18, respectively. No significant difference between no filtration and aluminum filtration (p = 0.411) was noted. A significant difference was detected between no filtration and aluminum-copper filtration (p = 0.012). The combination of an aluminum filter and a 75% standard dose achieved a 31.1% reduction in skin entrance dose. CONCLUSION: It is possible to achieve a 31.1% reduction in skin entrance dose for imaging bony structures by using 75% of the standard dose and aluminum filtration without significantly affecting image quality.

Perfusion CT of head and neck cancer: effect of arterial input selection.

OBJECTIVE: The purpose of this study is to evaluate the effect of arterial input selection on perfusion CT parameters of head and neck tumors. MATERIALS AND METHODS: Perfusion calculations were done for 50 cases using deconvolution-based software. Peak enhancement values of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) were recorded. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface area product were calculated using ipsilateral ECA, ipsilateral ICA, and contralateral ICA as input arteries. Values were compared using Wilcoxon's matched pair test and Pearson's correlation coefficients (r). RESULTS: A highly significant correlation was observed between peak enhancement values of the ICA and ECA (r = 0.97; p < 0.0001). A high correlation was observed between perfusion calculations obtained using ipsilateral ICA and ECA (BF, r = 0.98; BV, r = 0.92; MTT, r = 0.91; and permeability surface area product, r = 0.89), ipsilateral and contralateral ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.93; and permeability surface area product, r = 0.89), as well as left and right ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.94; and permeability surface area product, r = 0.88). All correlations were statistically significant (p < 0.0001). No significant differences were observed between perfusion calculations obtained using ipsilateral ICA versus ECA, ipsilateral versus contralateral ICA, or left versus right ICA (p > 0.05). CONCLUSION: Arterial input selection has no significant effect on perfusion CT calculation of head and neck cancer. For standardization and simplification of postprocessing, we recommend the use of the ICA instead of the ECA as the arterial input because of its better visualization, perpendicular course, and larger caliber, all of which decrease partial volume effects.

MR-compatible assistance system for biopsy in a high-field-strength system: initial results in patients with suspicious prostate lesions.

PURPOSE: To examine the feasibility and safety of magnetic resonance (MR)-guided biopsy by using a transgluteal approach in patients with suspicious prostate lesions by using an MR-compatible robotic system and a 1.5-T MR system. MATERIALS AND METHODS: The study was approved by the institutional review board of University Frankfurt, and informed consent was obtained from each patient. A total of 20 patients (age range, 57.8-71.9 years; mean age, 65.1 years) underwent biopsy in a closed-bore high-field-strength MR system. Biopsy was performed with an MR-compatible pneumatically driven robotic system. T1-weighted gradient-echo fast low-angle shot and T2-weighted true fast imaging with steady-state precession sequences were used to plan and guide the intervention with a transgluteal access on the external planning computer of the assistance system. The system calculated the trajectory and then moved the guiding arm to the insertion point. The cannula was advanced manually, and biopsies were performed with the coaxial technique by using a 15-gauge pencil tip needle. Intervention time, complications, and biopsy findings were documented. RESULTS: The MR-compatible robotic system did not interfere with image quality, nor did MR imaging cause dysfunction of the robot. In one patient, the interventionist caused a fail-safe system shutdown. This was due to inadvertent displacement of the guiding arm during cannula insertion. This problem was solved by increasing the displacement threshold. Accurate coaxial cannula biopsy could be performed in all subsequent patients. Sufficient histopathologic assessment was performed in 19 patients. Insufficient material was retrieved in the patient who experienced fail-safe system shutdown. The median intervention time was 39 minutes (23-65 minutes). No procedure-related complications were observed. CONCLUSION: Preliminary results indicate that MR-guided robot-assisted biopsy is feasible and can be performed safely with highly accurate cannula placement.

Low-dose computed tomography of the paranasal sinus and facial skull using a high-pitch dual-source system--first clinical results.

OBJECTIVE: Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. METHODS: Examinations were performed on a second-generation dual-source CT with a pitch factor of 3.0 (dual-source mode). Images were compared with those with a pitch factor of 0.9 on the same system (single-source mode) and with those of 16-slice CT. Image quality was evaluated by four blinded readers using a 5-point scale (1=poor, 5=excellent). Comparison of the dose length product (DLP) was used to estimate radiation exposure. RESULTS: Seventy-three consecutive patients underwent imaging with the proposed CT protocols. The viewers rated the image quality of the dual-source image sets as nearly as good (3.62) as the single-source images on the same device (4.18) and those on 16-slice CT (3.7). DLP was cut to half of the dose [51 mGycm vs. 97.8 mGycm vs. 116.9 mGycm (p<0.01)]. CONCLUSIONS: Using the proposed dual-source mode when examining the paranasal sinus, diagnostic image quality can be achieved while drastically lowering the patient's radiation exposure.

Repeated chemoembolization followed by laser-induced thermotherapy for liver metastasis of breast cancer.

OBJECTIVE: The purpose of this study was to evaluate local tumor control and survival after use of a downstaging protocol of repeated transarterial chemoembolization (TACE) with two chemotherapeutic combinations followed by laser-induced thermotherapy in the care of patients with liver metastasis of breast cancer. SUBJECTS AND METHODS: This prospective study included 161 patients with liver metastasis of breast cancer origin. TACE (mean, 3.5 [SD, 1.3] sessions per patient; range, 1-9 sessions) was performed as downstaging treatment to achieve the size and number of metastatic lesions that met the requirements for laser-induced thermotherapy (diameter < 5 cm, number ≤ 5). The TACE protocol was performed with either mitomycin C alone (n = 53) or mitomycin C in combination with gemcitabine (n = 108). RESULTS: In response to TACE overall, the mean reduction in diameter based on the longest diameter of the target lesions was 27%. The difference between diameter reduction in the mitomycin C group and that in the mitomycin C-gemcitabine group was not statistically significant (p = 0.65). The mean survival time of all patients was 32.5 months, calculation starting from the first TACE treatment. The mean local tumor control period calculated as of completion of therapy was 13 months, and the mean time to progression was 8 months. In the mitomycin-gemcitabine group, mean time to progression was 10.7 months, and in the mitomycin group it was 6.9 months (p = 0.5). CONCLUSION: TACE can be used for sufficient downstaging of liver metastatic lesions of breast cancer to allow laser-induced thermotherapy. A combination of mitomycin C and gemcitabine seems to improve the reduction achieved with TACE.

CT-guided pericardiocenteses: clinical profile, practice patterns and clinical outcome.

OBJECTIVE: To assess the effectiveness and clinical outcome and technique of CT-guided pericardiocenteses in the treatment of pericardial effusions in adults and children. METHODS: 20 drainages were performed in Seldinger-technique under CT-guidance on 20 patients suffering from pericardial effusions and haematomas. In 85%, the etiology of effusion was postoperative. The mean age of the patients was 59 years (minimum 9 years, maximum 86 years).There were 12 male and eight female patients. The inclusion criterion was an echocardiographically relevant proved pericardial effusion. RESULTS: All catheters could be placed successfully (20/20) in the pericardial effusion and allowed for draining of the effusion in all cases under CT-guidance. The overall 30-day mortality rate was 0%. CT-guided pericardiocentesis was successful for withdrawing pericardial fluid and/or relieving tamponade in 100% of all procedures. No major complication was occurred. A total of one minor complication (5%) occurred that required no specific interventions, except for monitoring and appropriate follow-up. We observed one pneumothorax as a minor complication. CONCLUSIONS: Pericardial effusions of various causes can be safely, effectively, and quickly managed with CT-guided pericardiocenteses in adults and children. The ventrolateral entry side for the puncture should be preferred to reach the whole effusion and avoid complications, like a pneumothorax.

An exploratory pilot study into the association between microcirculatory parameters derived by MRI-based pharmacokinetic analysis and glucose utilization estimated by PET-CT imaging in head and neck cancer.

OBJECTIVES: To examine the feasibility of deriving quantitative microcirculatory parameters and to investigate the relationship between vascular and metabolic characteristics of head and neck tumours in vivo, using dynamic contrast-enhanced (DCE) MRI and fluorodeoxyglucose (FDG) PET imaging. METHODS: Twenty-seven patients with primary squamous cell carcinoma (SCCA) underwent DCE-MRI and combined PET/CT imaging. DCE-MRI data were post-processed by using commercially available software. Transfer constant (K (trans)), extravascular extracellular blood volume (v (e)), transfer constant from the extracellular extravascular space to plasma (k (ep)) and iAUC (initial area under the signal intensity-time curve) were calculated. 3D static PET data were acquired and standardised uptake values (SUV) calculated. RESULTS: All microcirculatory parameters in tumours were higher than in normal muscle tissue (P ≤ 0.0019). Significant correlations were shown between k (ep) and K (trans) (ρ = 0.77), v (e) and k (ep) (ρ = -0.7), and iAUC and v (e) (ρ = 0.53). Significant correlations were observed for SUV(mean) and v (e) as well as iAUC (ρ = 0.42 and ρ = 0.66, respectively). SUV(max) was significantly correlated with iAUC (ρ = 0.69). CONCLUSIONS: The demonstrated relationships between vascular and metabolic characteristics of primary SCCA imply a complex interaction between vascular delivery characteristics and tumour metabolism. The lack of correlation between SUV and K (trans)/k (ep) suggests that both diagnostic techniques may provide complementary information.

Cuff overinflation and endotracheal tube obstruction: case report and experimental study.

BACKGROUND: Initiated by a clinical case of critical endotracheal tube (ETT) obstruction, we aimed to determine factors that potentially contribute to the development of endotracheal tube obstruction by its inflated cuff. Prehospital climate and storage conditions were simulated. METHODS: Five different disposable ETTs (6.0, 7.0, and 8.0 mm inner diameter) were exposed to ambient outside temperature for 13 months. In addition, every second of these tubes was mechanically stressed by clamping its cuffed end between the covers of a metal emergency case for 10 min. Then, all tubes were heated up to normal body temperature, placed within the cock of a syringe, followed by stepwise inflation of their cuffs to pressures of 3 kPa and > or =12 kPa, respectively. The inner lumen of the ETT was checked with the naked eye for any obstruction caused by the external cuff pressure. RESULTS: Neither in tubes that were exposed to ambient temperature (range: -12 degrees C to +44 degrees C) nor in those that were also clamped, visible obstruction by inflated cuffs was detected at any of the two cuff pressure levels. CONCLUSIONS: We could not demonstrate a critical obstruction of an ETT by its inflated cuff, neither when the cuff was over-inflated to a pressure of 12 kPa or higher, nor in ETTs that had been exposed to unfavorable storage conditions and significant mechanical stress.

Comparison of bipartite versus tripartite osteotomy for maxillary transversal expansion using 3-dimensional preoperative and postexpansion computed tomography data.

PURPOSE: To evaluate tripartite paramedian versus bipartite median osteotomy in surgically assisted rapid maxillary expansion. Tripartite osteotomy was performed between the lateral incisors and canines at the former premaxillary junction to avoid midline diastema, septal and columellar dislocation, and asymmetric expansion, minimizing high-distraction forces through bilateral doubled osteotomy on periodontia and thus reducing vestibular attachment loss and producing stable callus formation to avoid relapse. PATIENTS AND METHODS: The preoperative and postexpansion computed tomography data from 50 patients were analyzed in multiplanar viewing for bodily segment movement, vestibular bone loss, and transverse skeletal and dental widening with predefined landmarks. Of the 50 patients, 22 had undergone tripartite and 28 had undergone bipartite osteotomy. RESULTS: Using an independent t test, both osteotomies permitted adequate transverse skeletal expansion in the premolars, converging, however, in the molars. Bipartite osteotomy resulted in less symmetry in transverse skeletal widening, greater bodily segment movement in the first premolar/molar, and greater vestibular bone loss. Tripartite osteotomy resulted in greater overall expansion and less bone remodeling. On variance analysis, tripartite bone-borne distraction resulted in the greatest decrease of transverse expansion in patients older than 20 years. The tripartite osteotomy also provoked distractor- and age-independent outward segmental movement. Bipartite osteotomy resulted in distractor- and age-independent inward segmental movement. Bipartite osteotomy showed the greatest bone resorption in patients younger than 20 years old in the molars and tripartite osteotomy in patients older than 20 years in the premolars. CONCLUSIONS: Tripartite paramedian osteotomy allowed greater overall symmetric expansion compared with bipartite median osteotomy, with, however, a decline in transverse widening to the posterior. Bipartite osteotomy should be preferred whenever good periodontal status permits greater vestibular bone loss and a midline diastema and asymmetric expansion and a midline shift will be tolerated by the patient. Tripartite osteotomy should be chosen whenever a midline diastema and shift, septal and columellar dislocation, asymmetric expansion, and larger distraction forces on the paradontia, resulting in vestibular attachment loss, are to be avoided.

Evaluation of surgically assisted rapid maxillary expansion with or without pterygomaxillary disjunction based upon preoperative and post-expansion 3D computed tomography data.

UNLABELLED: PURPOSE, METHODS: This study (50 patients; Ø 25 years) compared surgically assisted rapid maxillary expansion (SARME) with (+/-PP) to SARME without pterygomaxillary (-PP) disjunction due to dentoskeletal effects in 3D CT preoperatively and Ø 11 weeks post-expansion. RESULTS: In t test, SARME-PP declined in transverse width from anterior to posterior but more symmetrically than SARME+PP. It produced more segmental inclination and vestibular bone resorption in the premolars. SARME+PP also declined in transverse width from anterior to posterior but more asymmetrically with an extreme convergence to the molars. It produced more segmental inclination and vestibular bone resorption (second molar) in the molars and a palatal bone plate thickness increase in the second premolar. With variance analysis, a further differentiation between the two independent groups due to secondary variables was made: SARME+PP produced the biggest decline in transverse width (patients <20 years) and the biggest segmental outward inclination from anterior to posterior in patients with bone-borne devices. SARME-PP in patients <20 years and SARME+PP in patients >20 years both produced the biggest lateral pterygoid bending. CONCLUSION: Pterygomaxillary disjunction should be based on patient age and individual requirements, i.e., in patients <20 years (SARME-PP) and >20 years (SARME+PP).