Morphometric analysis of the petrous bone - A preliminary study of intra- and inter-observer variation of basic measurements.

Studies of cremated skeletal remains show that the petrous part of the temporal bone often survives the burning process due to its dense and robust structure. Because of its frequent occurrence and well preservation in skeletal material from archaeological and forensic context, it has repeatedly been investigated for patterns of sexual dimorphism and potential to estimate sex from skeletal remains. Although being a relatively small skeletal element, the posterior part of the petrous bone has several anatomical features that serve as characteristic landmarks for the application of metric studies. Furthermore, sex-specific differences have also been recognised for the dimensions of the medial and lateral angle of the Internal acoustic canal (IAC). However, the accuracy of estimating an individual's sex based on measurements of the petrous bone has met with varying degrees of success. The purpose of this study was to see how well certain variables were identified and measured, but also to recognise the reproducibility of the results. In an initial approach five variables were selected and measured on ten petrous bones from an archaeological context. In addition, a total of forty casts were prepared in order to measure the angular dimensions. It was found that the basic measurements of all variables show high variations, but in only one variable, measurements were very inconsistent as evidenced by the large intra- and inter-observer errors. In terms of the angle dimension the results show that the range of variation was higher for the lateral angle and that the intra-observer error was found to be much lower for the medial angle than for the lateral one. The results show potential in the use of these methods in terms of repeatability, but also indicate that the metric assessment is prone to false application caused by the morphological variations of the individual landmarks.

MRI of the TMJ: morphometric comparison of asymptomatic volunteers and symptomatic patients.

OBJECTIVE: Morphologic and morphometric differences in the anatomy of the temporomandibular joint (TMJ) between asymptomatic volunteers and patients with temporomandibular disorders (TMDs) were evaluated using magnetic resonance imaging (MRI). METHOD AND MATERIALS: Forty volunteers were examined using a 1.5-T MRI and double surface coils. Both temporomandibular joints were imaged simultaneously; 78 joints could be evaluated. Each TMJ was examined in the intercuspal position in a parasagittal plane. Images were analyzed morphometrically and morphologically and compared to data retrospectively obtained from 91 age-matched patients. RESULTS: Considering the position of the disc morphologically, 66.7% of the volunteers had a normal disc position while 28.6% of the patients did. Anterior disc displacement with reduction was diagnosed in 33.3% of volunteers and 31.0% of the patients. Anterior disc displacement without reduction was found only in patients (19.2%). Comparison of morphometric data between patients and volunteers revealed shortening of the disc and a thickening in the intermedial part and the posterior band in patients. In patients, the disc presented anteriorly and the condyle was positioned superiorly and posteriorly in the mandibular fossa when compared to the volunteers. Therefore, the posterior and superior joint spaces were smaller in patients. Women showed disc displacement and combined morphometric changes in the TMJ structures significantly more often than men. CONCLUSION: A large variation of morphometric parameters in temporomandibular joints could be demonstrated. However, reduced disc length, thickening of the disc, narrowed interarticular superior and posterior distances, and a superior-posterior position of the condyle are more commonly associated with joint pathology.

Intervertebral disc regeneration after implantation of a cell-free bioresorbable implant in a rabbit disc degeneration model.

Degeneration of the intervertebral disc is the most common cause of lower back pain. Interestingly, all available treatments are limited to treat the symptoms and not the underlying biologic alterations of the disc. Freeze-dried resorbable non-woven polyglycolic acid (PGA) - hyaluronan implants were used in a degenerated disc disease (DDD) model in New Zealand white rabbits. The constructs were immersed in allogenic serum and implanted into the disc defect. Animals with discectomy only served as controls. The T2-weighted/fat suppression sequence signal intensity of the operated discs as assessed by magnet resonance imaging decreased in both groups one week after the operation compared to a healthy disc. After 12 months the implanted group showed an increase of 51% in the signal intensity compared to the 1-week results whereas the signal intensity in the sham group remained on the same level from one week to 12 months. Histological and quantitative immunohistochemical examination after 12 months indicated cell migration into the defect and showed formation of disc repair tissue. In controls, repair tissue containing type II collagen was not evident. In conclusion, the implantation of polymer-based constructs after discectomy induces tissue regeneration resulting in improvement of the disc water content.

Prediction of postoperative outcome after hepatectomy with a new bedside test for maximal liver function capacity.

OBJECTIVE: To validate the LiMAx test, a new bedside test for the determination of maximal liver function capacity based on C-methacetin kinetics. To investigate the diagnostic performance of different liver function tests and scores including the LiMAx test for the prediction of postoperative outcome after hepatectomy. SUMMARY BACKGROUND DATA: Liver failure is a major cause of mortality after hepatectomy. Preoperative prediction of residual liver function has been limited so far. METHODS: Sixty-four patients undergoing hepatectomy were analyzed in a prospective observational study. Volumetric analysis of the liver was carried out using preoperative computed tomography and intraoperative measurements. Perioperative factors associated with morbidity and mortality were analyzed. Cutoff values of the LiMAx test were evaluated by receiver operating characteristic. RESULTS: Residual LiMAx demonstrated an excellent linear correlation with residual liver volume (r = 0.94, P < 0.001) after hepatectomy. The multivariate analysis revealed LiMAx on postoperative day 1 as the only predictor of liver failure (P = 0.003) and mortality (P = 0.004). AUROC for the prediction of liver failure and liver failure related death by the LiMAx test was both 0.99. Preoperative volume/function analysis combining CT volumetry and LiMAx allowed an accurate calculation of the remnant liver function capacity prior to surgery (r = 0.85, P < 0.001). CONCLUSIONS: Residual liver function is the major factor influencing the outcome of patients after hepatectomy and can be predicted preoperatively by a combination of LiMAx and CT volumetry.

Regeneration of intervertebral disc tissue by resorbable cell-free polyglycolic acid-based implants in a rabbit model of disc degeneration.

STUDY DESIGN: : Different biologic strategies exist to treat degenerative disc disease. Tissue engineering approaches favor autologous chondrocyte transplantation. In our one-step-approach, a resorbable cell-free polyglycolic acid (PGA)-based implant is immersed in serum from whole blood and implanted into the disc defect directly after discectomy. OBJECTIVES: : The aim of our study was to investigate the capacity of a cell-free implant composed of a PGA felt, hyaluronic acid, and serum to recruit disc cells and stimulate repair tissue formation in vivo after microdiscectomy in a rabbit model. SUMMARY OF THE BACKGROUND DATA: : Disc tissue has a limited ability to regenerate after the degeneration process was once initiated. Therefore, we developed a cell-free resorbable implant that is able to attract local cells into the defect and induce proper repair tissue formation. METHODS: : The cell-free implant consisting of PGA and hyaluronic acid was immersed in allogenic serum and implanted into the disc defect after discectomy in New Zealand white rabbits. One week and 6 months after the operation, the disc height index and the T2-weighted signal intensity index were determined using plane radiographs and magnetic resonance imaging. Finally, discs were explanted and investigated histologically. Animals with discectomy only served as controls. RESULTS: : In our animal studies, we could demonstrate that the T2-weighted signal intensity of the operated discs decreased in both groups 1 week after surgery. However, after 6 months, the T2-weighted signal intensity index increased by 45% in the implanted group whereas the index decreased further by 11% in the sham group. This corresponded to changes in the disc height index. Furthermore, the histologic examinations indicated cell migration into the defect and showed tissue regeneration. CONCLUSION: : The implantation of a cell-free PGA-hyaluronic acid implant immersed in serum after discectomy induces regeneration, resulting in improvement of the disc water content and preservation of the disc height 6 months after surgery.

Retinoblastoma - MR appearance using a surface coil in comparison with histopathological results.

PURPOSE: The purpose of this work was to evaluate the characteristic appearance of untreated retinoblastoma on a large sample in comparison to the histological findings after therapeutical enucleation. MATERIALS AND METHODS: In a prospective clinical trial 46 children with retinoblastoma in 63 affected untreated eyes were examined under general anesthesia on MRI using a 1.5-T system. The examinations were performed with a special surface coil applying an examination protocol including fast T2- and T1-weighted spin echo sequences and additional fast T1-WI after intravenous injection of Gd-DTPA in different planes. The imaging results were compared to the histopathological findings in 29 patients with 30 affected eyes. RESULTS: Comparing MRI findings and histopathological results, optic nerve infiltration was detected with a sensitivity of 53.8% and a specificity of 82.3% on MRI, infiltration of the choroid with a sensitivity of 75.0% and a specificity of 100.0%, and the degree of tumor calcification with a sensitivity of 91.7% and a specificity of 88.9%. In this study the characteristic MR appearance of untreated retinoblastoma was evaluated. CONCLUSION: MRI was helpful in relevant aspects of pretherapeutical retinoblastoma staging, deficits remain regarding optic nerve infiltration.

Correlative imaging strategies implementing CT, MRI, and PET for staging of childhood Hodgkin disease.

BACKGROUND: The value of different correlative imaging strategies with F18-fluorodeoxyglucose positron emission tomography (FDG-PET) and conventional imaging modalities (CIM) for initial staging of pediatric Hodgkin disease (HD) was assessed. METHODS: Thirty-three patients (age, 4 to 18 y) with histologically proven HD underwent initial staging with computed tomography (thorax), magnetic resonance imaging (neck, abdomen, pelvis), and FDG-PET in a prospective study. Image fusion (PET-CIM) was performed using a semiautomatic voxel-based algorithm. Analysis of separate, side-by-side (SBS) and fused PET and CIM was performed evaluating 21 nodal and 6 extranodal regions per patient for presence of lymphoma, applying a 5-point confidence scale. The reference data was clinical follow-up (>12 mo). RESULTS: Concerning lymph node regions above and below the diaphragm the accuracy of CIM, PET, SBS, and image fusion was 86%, 89%, 94%, 97%, and 94%, 94%, 97%, 98%. In extranodal regions, the accuracy was 96%, 96%, 100%, and 100%. The reviewers' confidence was improved significantly by image fusion. Staging and therapy assignment on the basis of CIM was correctly modified by SBS in 5 and 4, by image fusion in 7 and 5 patients. CONCLUSIONS: Combined reading of FDG-PET and CIM is crucial for accurate staging in pediatric HD. Image fusion improves the observers' confidence and has impact on the therapeutic management.

Living donor right liver lobes: preoperative CT volumetric measurement for calculation of intraoperative weight and volume.

PURPOSE: To prospectively develop equations for the calculation of expected intraoperative weight and volume of a living donor's right liver lobe by using preoperative computed tomography (CT) for volumetric measurement. MATERIALS AND METHODS: After medical ethics committee and state medical board approval, informed consent was obtained from eight female and eight male living donors (age range, 18-63 years) for participation in preoperative CT volumetric measurement of the right liver lobes by using the summation-of-area method. Intraoperatively, the graft was weighed, and the volume of the graft was determined by means of water displacement. Distributions of pre- and intraoperative data were depicted as Tukey box-and-whisker diagrams. Then, linear regressions were calculated, and the results were depicted as scatterplots. On the basis of intraoperative data, physical density of the parenchyma was calculated by dividing weight by volume of the graft. RESULTS: Preoperative measurement of grafts resulted in a mean volume of 929 mL +/- 176 (standard deviation); intraoperative mean weight and volume of the grafts were 774 g +/- 138 and 697 mL +/- 139, respectively. All corresponding pre- and intraoperative data correlated significantly (P < .001) with each other. Intraoperatively expected volume (V(intraop)) in millilliters and weight (W(intraop)) in grams can be calculated with the equations V(intra)(op) = (0.656 . V(preop)) + 87.629 mL and W(intra)(op) = (0.678 g/mL . V(preop)) + 143.704 g, respectively, where preoperative volume is V(preop) in milliliters. Physical density of transplanted liver lobes was 1.1172 g/mL +/- 0.1015. CONCLUSION: By using two equations developed from the data obtained in this study, expected intraoperative weight and volume can properly be determined from CT volumetric measurements.

Proton therapy of uveal melanomas: intercomparison of MRI-based and conventional treatment planning.

BACKGROUND AND PURPOSE: Proton therapy for uveal melanoma provides high-conformal dose application to the target volume and, thus, an optimal saving of the organs at risk nearby. Treatment planning is done with the model-based treatment-planning system EYEPLAN. Tumor reconstruction is based only on a fundus composite, which often leads to an overestimation of the clinical target volume (CTV). The purpose was to exploit MRI on trial in a proton therapy-planning system by using the novel image-based treatment-planning system OCTOPUS. PATIENTS AND METHODS: Ten patients with uveal melanomas received both a high-resolution planning CT and MRI of the eye. MR examinations were made with an eye coil. EYEPLAN requires eye geometry data for modeling, and tantalum marker clips for submillimeter positioning and additional information from ultrasound and 3-D imaging. By contrast, OCTOPUS provides the full integration of 3-D imaging (e. g., CT, MRI). CTVs were delineated in each slice. For all patients, CTVs (EYEPLAN vs. OCTOPUS) were compared intraindividually. RESULTS: OCTOPUS planning led to a mean reduction of the target volume by a factor of 1.7 (T1-weighted [T1w]) and 2.2 (T2w) without compromising safety. The corresponding field size could be scaled down on average by a factor of 1.2 (T1w) and 1.4 (T2w), respectively. CONCLUSION: Compared with the conventional EYEPLAN, MRI-based treatment planning of ocular tumors with OCTOPUS could be a powerful tool for reducing the CTV and, consequently, the treatment volume and the field size. This might be translated into a better patient compliance during treatment and a decreased late toxicity.

Development and evaluation of phantom for verification of section thickness at thin-section MR imaging.

The purpose of this study was to construct and evaluate a phantom for measurement of magnetic resonance (MR) imaging sections with thicknesses of 0.3-0.6 mm. The phantom consisted of 304 0.1-mm-thick disks, each of which had a single notch filled with a diluted solution of gadopentetate dimeglumine. Qualitative and quantitative evaluations of T1-weighted images with section thicknesses of 0.3-0.6 mm were performed. A computer simulation was performed to evaluate the influence of different examination angles. At quantitative evaluation, the difference between nominal and measured section thicknesses ranged from 11% (nominal section thickness, 0.6 mm) to 18% (nominal section thickness, 0.4 mm). Computer simulations revealed that the phantom's positioning along the z-axis had a negligible influence at quantitative evaluation.

Eye imaging with a 3.0-T MRI using a surface coil--a study on volunteers and initial patients with uveal melanoma.

MRI of uveal melanoma using 1.5-T technology and surface coils has developed into a standard procedure. The purpose of the study was to evaluate the feasibility of 3.0-T technology in eye imaging. To optimize the MRI sequences for clinical eye imaging with 3.0-T, six healthy volunteers were conducted using a 4.0-cm surface coil. Evaluation criteria were the signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR) and image quality. A further six patients with uveal melanoma were examined with 1.5- and 3.0-T under retrobulbar anesthesia. During 3.0-T examinations of volunteers, eye movements caused significant artifacts. On the contrary, excellent imaging quality was reached in examinations of patients under retrobulbar anesthesia at 3.0 T. Subjective assessment showed no significant difference between 1.5 and 3.0 T in patients. Due to the increased SNR, the 3.0-T technique has the potential to improve eye imaging, but the higher susceptibility to motion artifacts limits the clinical use of this technique to patients receiving retrobulbar anesthesia.

Retrospective digital image fusion of multidetector CT and 18F-FDG PET: clinical value in pancreatic lesions--a prospective study with 104 patients.

UNLABELLED: Differential diagnosis of pancreatic lesions still remains a problem. Whereas CT provides high spatial resolution, PET detects malignant lesions with high sensitivity. The objective of this study was to evaluate the clinical benefit of PET/CT image fusion in the diagnostic workup of pancreatic cancer. METHODS: One hundred four patients with suspected pancreatic lesion underwent triple-phase multidetector CT and (18)F-FDG PET scanning. Voxel-based retrospective registration and fusion of CT and PET were performed with recently developed software. CT, PET, and fused images were assessed by 2 radiologists with regard to the detection of malignancies, possible infiltration of adjacent tissue or lymph nodes, or distant metastases. RESULTS: Fusion of CT and PET images was technically successful in 96.2%. In 2 cases, paraaortic lymph node infiltration was detected only by image fusion; in a further 8 cases, lymph node metastases were confirmed with improved localization. In 5 patients, additional pancreatic tumors or distant metastases only suspected during PET scanning were confirmed. Image fusion improved the sensitivity of malignancy detection from 76.6% (CT) and 84.4% (PET) to 89.1% (image fusion). Compared with CT alone, image fusion increased the sensitivity of detecting tissue infiltration to 68.2%, but at the cost of decreased specificity. CONCLUSION: The most important supplementary finding supplied by image fusion is a more precise correlation with focal tracer hot spots in PET. Image fusion improved the sensitivity of differentiating between benign and malignant pancreatic lesions with no significant change in specificity. All image modalities failed to stage lymph node involvement.