Cirugía guiada para la colocación de implantes de longitud estándar en maxilar inferior posterior atrófico, sin regeneración ósea: informe de caso / Use of guided surgery for standard length implant placement in atrophic posterior mandible, without bone regeneration: case report

Objetivo: Presentar el uso de la cirugía guiada para la resolución quirúrgico-protética de un caso clínico con colocación de implantes de longitud estándar (>7 mm) en un maxilar inferior atrófico, sin regeneración ósea guiada. Caso clínico: Una paciente que requería terapia con implantes en sectores posteroinferiores se presentó en la Cátedra de Odontología Integral Adultos de la Facultad de Odontología de la Universidad de Buenos Aires. Primero se realizó una tomografía computarizada de haz cónico del maxilar inferior para evaluar la disponibilidad ósea. La planificación se efectuó siguiendo un protocolo digital a fin de optimizar la selección de los implantes y su instalación en función de la futura rehabilitación protética y el tejido óseo disponible. Después se escanearon ambos maxilares y el registro intermaxilar; estas imágenes ­junto con las correspondientes a la tomografía (DICOM)­ fueron importadas como archivos (STL) a un software específico de diseño para determinar digitalmente la posición 3D ideal de los implantes y diseñar una guía quirúrgica de precisión. Luego se realizó la cirugía de instalación de los implantes con la guía quirúrgica, y finalmente los implantes fueron rehabilitados por medio de coronas cemento-atornilladas. Conclusión: El uso de la cirugía guiada permitió optimizar el tejido óseo disponible para la instalación de implantes en función de la futura rehabilitación protética (AU)

Aim: To present the use of guided surgery for the prosthetic resolution of a clinical case with placement of implants of standard length (>7 mm) in an atrophic posterior mandible, with no need of bone regeneration. Clinical case: A patient who required implants in the posterior sectors of the mandible attended to the department of Odontología Integral Adultos, Facultad de Odontología, Universidad de Buenos Aires, Argentina. A dental cone beam computed tomography (CBCT scan) of the lower jaw was done to assess bone availability and was decided to perform guided surgery for accurate implant placement. Both maxillaries and intermaxillary occlusal registration were scanned and imported into files (STL) together with those of the CBCT scan (DICOM) into specific design software. Following the digital protocol using a surgical guide the implants were placed and then restored with cemented-screwed crowns. Conclusion: Guided surgery allowed planning implant placement, guided by the final position of the prosthetic restoration, and optimizing the available bone (AU)

Preliminary study on application of augmented reality visualization in robotic thyroid surgery

PURPOSE: Increased robotic surgery is attended by increased reports of complications, largely due to limited operative view and lack of tactile sense. These kinds of obstacles, which seldom occur in open surgery, are challenging for beginner surgeons. To enhance robotic surgery safety, we created an augmented reality (AR) model of the organs around the thyroid glands, and tested the AR model applicability in robotic thyroidectomy. METHODS: We created AR images of the thyroid gland, common carotid arteries, trachea, and esophagus using preoperative CT images of a thyroid carcinoma patient. For a preliminary test, we overlaid the AR images on a 3-dimensional printed model at five different angles and evaluated its accuracy using Dice similarity coefficient. We then overlaid the AR images on the real-time operative images during robotic thyroidectomy. RESULTS: The Dice similarity coefficients ranged from 0.984 to 0.9908, and the mean of the five different angles was 0.987. During the entire process of robotic thyroidectomy, the AR images were successfully overlaid on the real-time operative images using manual registration. CONCLUSION: We successfully demonstrated the use of AR on the operative field during robotic thyroidectomy. Although there are currently limitations, the use of AR in robotic surgery will become more practical as the technology advances and may contribute to the enhancement of surgical safety.

Impact of point spread function on image quality and SUV in FDG PET imaging / 中华核医学与分子影像杂志

Objective To discuss the impact of an iterative reconstruction algorithm (True X) implemented with point spread function (PSF) on image quality and SUV in 18F-FDG PET, and compare with other reconstruction algorithms.Methods A total of 79 hypermetabolic lesions from 37 cancer patients (23 males, 14 females, age (63.38±15.25) years) were retrospectively studied.The PET images were reconstructed using the following six reconstruction algorithms, including FBP, FBP+TOF, iteration, iteration+TOF, True X, True X+TOF.Paired t test was used for statistical analysis.Results All six reconstruction algorithms showed significant difference in lesion SUVmax.The adoption of PSF increased SUVmax by 15%-16%, and decreased the dispersion of SUV in the liver parenchyma remarkably.Conclusions Lesion SUVmax calculated from different reconstruction algorithms has significant differences.Caution should be taken in using PSF, as it can improve image quality but may also increase lesion SUVmax.

Normal Mastoid Air Cell System Geometry: Has Surface Area Been Overestimated?

OBJECTIVES: The aim of this study was to emphasize the necessity of a standard in segmentation threshold and algorithm for measuring volume and surface area of mastoid air cell system (MACS). METHODS: First, we obtained axial computed tomography scans of 54 normal temporal bones from 27 subjects. Then, we manipulated Hounsfield units (HU) image data in DICOM (digital imaging and communications in medicine) files directly using our program. The volume and surface area of MACS were computed and compared at segmentation thresholds (HU) from -700 to 0 at intervals of 50 using 2 algorithms; square pixel based (SP) algorithm and marching square (MS) algorithm. RESULTS: No significant difference was found between the volumes computed by SP and MS algorithms at each segmentation threshold. The surface area computed by SP algorithm, however, was significantly larger than that by MS algorithm. We could minimize this significant difference through a modification of the SP algorithm. As the lower HU threshold value was set, the smaller volume was measured. The surface area showed a plateau at a threshold of approximately -200 HU. The segmentation threshold had greater influence on the measured volume of MACS than the algorithm did. CONCLUSION: A standard method for measuring volume and surface area of MACS is thought to be necessary. We suggest that the MS algorithm and -200 HU of the threshold could be a standard in the measurement of volume and surface area of MACS.

Preliminary study of gastric carcinoma volume measurement using computed tomography for N staging evaluation / 实用放射学杂志

Objective To evaluate the value of volume measured by multi-slice spiral CT in preoperative N staging of gastric canc-er.Methods CT data of 1 93 cases of gastric cancer proven pathologically were collected and analyzed.Volume of the tumor was cal-culated in the portal phase,and the correlation between the results and N staging was evaluated.ROC curve was used to get diagnos-tic value to differentiate N stages.Results Intra-observer Kappa value was 0.77 (P < 0.05 ),0.72 (P < 0.05 ),Inter-observer Kappa value was 0.69 (P <0.05).The tumor volume data was positively correlated with different N stages (r=0.568,P <0.05). ROC curve showed that the volume could help differentiate between stage N0 and stage N1 - N3 (cutoff 12.06 cm3 ,sensitivity 55%,specificity 95%),stage N0-N1 and stage N2-N3 (cutoff 22.35 cm3 ,sensitivity 66%,specificity 86%),stage N0-N2 and stage N3 (cutoff 25.95 cm3 ,sensitivity 62%,specificity 89%)respectively.Conclusion The volume of gastric cancer measured by CT plays an important part in predicting lymph node metastasis staging and optimizing individualized clinical strategy for patients.

Angiotomografia computadorizada de coronárias com tomógrafo com 320 fileiras de detectores e utilizando o AIDR-3D: experiência inicial / Coronary computed tomography angiography with 320-row detector and using the AIDR-3D: initial experience

A angiotomografia computadorizada de coronárias (angioTC de coronárias) é um excelente método de imagem não invasivo para avaliar a doença arterial coronariana. Atualmente, a dose de radiação efetiva estimada da angioTC de coronárias pode ser reduzida em tomógrafos de última geração com múltiplos detectores, como o tomógrafo com 320 fileiras de detectores (320-CT), sem prejuízo na acurácia diagnóstica da angioTC de coronárias. Para reduzir ainda mais a dose de radiação, novos algoritmos de reconstrução iterativa foram recentemente introduzidos por vários fabricantes de tomógrafos, que atualmente são utilizados rotineiramente nesse exame. Neste trabalho, apresentamos nossa experiência inicial na angioTC de coronárias utilizando o 320-CT e o Adaptive Iterative Dose Reduction 3D (AIDR-3D). Apresentamos ainda as indicações mais comuns desse exame na rotina da instituição bem como os protocolos de aquisição da, angioTC de coronárias com as atualizações relacionadas a essa nova técnica para reduzir a dose de radiação. Concluímos que a dose de radiação da angioTC de coronárias pode ser reduzida seguindo o princípio as low as reasonable achievable (tão baixo quanto razoavelmente exequível), combinando a indicação de exame com técnicas bem documentadas para a diminuição da dose de radiação, como o uso de betabloqueadores e a redução do kV, com os mais recentes aplicativos de reconstrução iterativa para redução da dose de radiação, como o AIDR-3D.

Coronary computed tomography angiography (coronary CTA) is a powerful non-invasive imaging method to evaluate coronary artery disease. Nowadays, coronary CTA estimated effective radiation dose can be dramatically reduced using state-of-the-art scanners, such as 320-row detector CT (320-CT), without changing coronary CTA diagnostic accuracy. To optimize and further reduce the radiation dose, new iterative reconstruction algorithms were released recently by several CT manufacturers, and now they are used routinely in coronary CTA. This paper presents our first experience using coronary CTA with 320-CT and the Adaptive Iterative Dose Reduction 3D (AIDR-3D). In addition, we describe the current indications for coronary CTA in our practice as well as the acquisition standard protocols and protocols related to CT application for radiation dose reduction. In conclusion, coronary CTA radiation dose can be dramatically reduced following the "as low as reasonable achievable" principle by combination of exam indication and well-documented technics for radiation dose reduction, such as beta blockers, low-kV, and also the newest iterative dose reduction software as AIDR-3D.

Anatomical variations of trabecular bone structure in intraoral radiographs using fractal and particles count analyses

PURPOSE: This study was performed to evaluate possible variations in maxillary and mandibular bone texture of normal population using the fractal analysis, particles count, and area fraction in intraoral radiographs. MATERIALS AND METHODS: Periapical radiographs of patients who had full mouth intraoral radiographs were collected. Regions of interest (100x100 pixels) were located between the teeth of the maxillary anterior, premolar, and molar area, as well as the mandibular anterior, premolar, and molar areas. The fractal dimension (FD) was calculated by using the box counting method. The particle count (PC) and area fraction (AF) analyses were also performed. RESULTS: There was no significant difference in the FD values among the different groups of age, gender, upper, and lower jaws. The mean FD value was 1.49+/-0.01. The mean PC ranged from 44 to 54, and the mean AF ranged from 10.92 to 11.85. The values of FD, PC, and AF were significantly correlated with each other except for the upper molar area. CONCLUSION: According to the results, patients with normal trabecular pattern showed a FD of approximately 1.5. Based on these results, further investigation would be recommended if the FD value of patient significantly differenct from this number, since the alteration of this value indicates microstructural modification of trabecular pattern of the jaws. Additionally, with periapical radiographs, simple and cost-effective, PC and AF could be used to assess the deviation from the normal.

Dual-energy CT in the evaluation of solitary pulmonary nodules by virtual non-enhanced images:initial experience / 中华放射学杂志

Objective To determine the accuracy and radiation dose of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules (SPNs) by virtual non-enhanced images.MethodsSixty-one patients with SPNs including 39 malignant and 18 benign nodules proved by pathology underwent DECT scans. The CT values of SPNs on enhanced weighted average and virtual non-enhanced images were compared by using Liver VNC processing unit in terms of their diagnostic accuracy for distinguishing malignant and benign nodules with a 20 HU threshold. Diagnostic accuracy was compared. In 28 patients of all patients, image noise and quality score of the non-enhanced and virtual non-enhanced images were compared, and radiation doses of each patient were recorded. The paired t test was used to analyze the noise difference between the plain scan and virtual non-enhanced scan. The Mann-Whitney U test was used to analyze statistically significant differences of the image quality score and radiation dose between the non-enhanced scan and virtual non-enhanced scan. ResultsThe sensitivity, specificity and accuracy for distinguishing benign and malignant nodules by using the virtual non-enhanced image of were 89. 7％(35/39), 72.2％ (13/18), 84.2％ (48/57)respectively.The noise of common CT and virtual nonenhanced images were(8. 49 ± 1. 94) HU and( 10. 14 ± 2. 18 ) HU, and there were statistically difference (t＝9.45,P＜0. 01 ). The quality scores of common CT and virtual non-enhanced images were (4.71 ±0. 46 ) and ( 4.42 ± 0. 57 ), and there were no statistical difference ( U ＝ 290. 00, P ＞ 0. 05 ). The radiation doses of common CT and DECT were ( 3. 72 ± 0. 48 ) mSv and ( 3.78 ± 0. 45 ) mSv, and there were no statistical difference ( U ＝ 350. 50,P ＞ 0. 05 ). ConclusionDECT by using virtual non-enhanced images is useful tool to distinguish the benign and malignant SPN without additional radiation dose.

Value of 18FDG PET-CT in the determination of treatment regimen in lung cancer / 中华放射肿瘤学杂志

can improve the accuracy of clinical staging and help to choose a proper treatment regimen. Moreover, it can clearly differentiate tumor from normal tis-sue and reduce the risk of geographic misses.

Value of ~(18)FDG PET-CT in detecting recurrence and metastasis in post-treatment esophageal carcinoma / 中华放射肿瘤学杂志

Objective To evaluate the clinical value of 18-fluoro-deoxyglucose positron emission tomography-CT(~(18)FDG PET-CT) for recurrence and metastasis in treated esophageal carcinoma (EC). Methods A retrospective study is done on 37 previously treated EC patients who underwent PET-CT scans to detect recurrent or metastatic lesions.The diagnostic accuracy of ~(18)FDG PET-CT was assessed with the help of pathological finding as well as clinical or follow-up data.Results Fourty-six sites of recurrence were finally confirmed in 37 patients by cytology,pathology or follow-up data.The sensitivity,specificity and accuracy of PET-CT in detecting recurrence of all sites were 93.5% (43/46),76.9% (20/26) and 87.5% (63/72),respectively.Two false-positive findings were found both at the anastomosis and hilar nodes,which caused the decrease in the overall specificity,especially that locally.The analysis of standard uptake value (SUV) demonstrated that patients with recurrence or who died during follow-up had higher SU- Vs compared with the control group.Condusions ~(18)FDG PET-CT is highly effective in detecting recur- rence in previously treated EC patients despite the low specificity at local sites.The analysis of stardard up- take value(SUV) provides incremental value in prognosis for this patient cohart.

Value of ~(18)FDG PET-CT in defining the length of esophageal cancer / 中华放射肿瘤学杂志

Objective To assess the value of 18-fluoro-deoxy-glucose positron emission-CT(FDG PET-CT) in defining the length of primary esophageal cancer.Methods Thirty-two patients had underg- one esophagoscopy,esophagography and FDG PET-CT scans one week before esophagectomy.There was one tumor located in the upper thoracic esophagus,22 in the middle thoracic esophagus,and 9 in the lower tho- racic esophagus.The location and length of primary lesion of the tumor was determined by esophagoscopy, esophagography,and FDG PET-CT.The length of the abnormality seen on the CT portion of the PET-CT scan was determined separately and independently by two radiologists.All results were compared with the resected specimen.Results According to esophagography,CT and PET-CT,all lesion lengths were compared with that of the resected specimen.It was found that the tumor location determined by esophagoscopy was not in accordance with the resected specimen in 2 patients.The mean length of the primary tumor,being from short to long,were (3.8?1.4),(4.1?1.5),(4.4?1.6),(5.3?1.9) and (4.7?1.7) cm,as determined by esophagoscopy,esophagography,CT,actral length of the resected specimen and PET-CT.Compared with the resected specimen,there was obvious difference (P=0.000,0.007,0.025,0.001).Considering that there might be some kind of shrinkage in the resected specimen (about 83.59%,as reported by Ma et al), we rectified the length of resected specimen and compared with other findings again.It was found that insig- nificant difference existed between PET-CT and rectified length value of the resected specimen (P=0.082). Conclusions FDG PET-CT is effective in the length determination of primary esophageal cancer.It may he used to determine the length of esophagus to be resected for patients indicated for esophagectomy.It may also be used to ac- curately delineate the gross tumor volume for patients eligible for radiotherapy.

CT evaluation and classification of the Le Fort fracture / 中华放射学杂志

Objective To evaluate the CT findings and classification of the Le Fort fracture. Methods Sixty-two cases with Le Fort fractures were studied with thin-slice high-resolution CT scanning and analyzed with three-dimensional(3D)imaging reconstruction.Results Of the 62 patients,10 had Le Fort type Ⅰ fracture,9 had Le Fort type Ⅱ fracture,8 had Le Fort type Ⅲ fracture,and 35 had various combinations of the three types of Le Fort fractures,including 18 Le Fort Ⅰ+Ⅱ fracture,7 Le Fort Ⅰ+ Ⅱ+Ⅲ fracture and 10 Le Fort Ⅱ+Ⅲ fracture.Fifty-five cases had associated multiple fractures in the maxillofacial region.On 2D CT images,Le Fort fracture manifested as multiple and complex fractures. Though 2D image was better than 3D image in accurately defining tiny fractures and fractures of deep structures,the diagnosis of Le Fort fracture could not be correctly made solely on 2D image.3D CT clearly and stereoscopically demonstrated the entire shape and orientation of Le Fort fracture,thus facilitating the correct classification of Le Fort fracture.Conclusion 3D CT image is important in providing information about the space relationship of Le Fort fracture,thus very valuable for the preoperative planning.

Three-dimensional contrast-enhanced MR angiography in diagnosis of cerebral arteriovenous malformation / 中华放射学杂志

Objective To evaluate the value of three-dimensional contrast-enhanced angiography (3D CE MRA) and MRI in the diagnosis and delineation of cerebral arteriovenous malformation(AVM). Methods Twenty-two cases of cerebral AVM examined by MRI and 3D CE,MRA.DSA was performed in 17 cases.A three-dimensional fast low angle shot (3D FLASH) was used for 3D CE MRA with Gd-DTPA dosage of 0.2 mmol per kilogram for body weight.The source images were subtracted from mask images and transferred to computer workstation using three-dimensional reconstruction.Results Among 22 cases, 19 showed typical AVM“flow void”signal on MR images.3D CE MRA clearly displayed the nidus,feeding artery and draining vein.All of the foci were above the cerebellum tentorium.13 located within one lobe, 3 exceeded one lobe and 3 situated in the deep of cerebrum.Feeding arteries were derived from single artery in 9 cases,and mixed supply in 10 cases.Draining veins diverted to sagittal sinus and/or sigmoid sinus in 6,deep cerebral veins in 8 and mixed in 5.In the 14 cases examined by both DSA and 3D CE MRA,3D CE MRA was superior to DSA in three-dimensional demonstration of the nidus,but inferior to DSA in demonstration of some details.3D CE MRA depicted 78.4% feeding arteries and 84.0% draining veins in addition,tiny pathologic blood vessels smaller than 1 centimeter were detected by DSA,but could not be found by 3D CE MRA and were only shown as hemorrhage lesions on MR images in 3 cases.Conclusion As a non-invasive technique,3D CE MRA combined with MRI is accurate in diagnosis and localization of cerebral AVM,and should be used as the first choice for those clinically suspected of AVM.But DSA remains needed for demonstration of details and tiny AVM.

The diagnostic value of three-dimensional dynamic contrast-enhanced MR angiography for intracranial aneurysms / 中华放射学杂志

Objective To assess the clinical value of three dimensional dynamic contrast enhanced MR angiography (3D DCE MRA) in the detection for intracranial aneurysm. Methods 3D DCE MRA was performed in 54 patients highly suspected with intracranial aneurysms. Then conventional digital subtraction angiography (DSA) and feasible endovascular treatment were performed simultaneously. A three dimensional fast imaging with steady state precession (3D FISP) was used for 3D DCE MRA(Gd DTPA dose, 0.2 mmol per kilogram for body weight; acquisition time, 10 seconds). The source images were subtracted from mask images and transferred to computer workstation. All images were subsequently post processed using three dimensional reconstruction. 3D DCE MRA images and DSA images were compared for demonstration of the aneurysm, its neck, and relationship with parent artery, and the usefulness for endovascular treatment was evaluated. Results There were 39 cases with 45 intracranial aneurysms. The sensitivity, specificity, and accuracy of 3D DCE MRA were 96%, 73%, and 90%, respectively. Aneurysm and its neck depiction at 3D DCE MRA was significantly better than that at DSA, especially for aneurysms adjacent to the cavernous sinus and near the PICA of vertebral artery. 3D DCE MRA could guide neurosurgeons to the desired DSA projection, and helped them make plan for interventional or surgical treatment in advance. But the diagnosis should be very carefully made for small aneurysms located in the periphery and the arterial bifurcation. Conclusion 3D DCE MRA is a fast, noninvasive and efficient technique for diagnosing intracranial aneurysms. Its three dimensional information is helpful for DSA demonstration and treatment planning. Any uncertain diagnosis requires DSA confirmation.

The value of multi-direction adjusting multi-planar reformation in displaying the ossicles / 中华放射学杂志

Objective To study the positions and ways of displaying the panorama of the ossicles in one plane respectively by multi-direction adjusting multi-planar reformation (MPR). Methods Fifty normal middle ears were scanned by using the HRCT isotropic parameters, and multi-direction adjusting MPR was performed to find out the basic positions, the rotating central point of reformation basic line, and the anatomic structure orientated the adjusting directions. The angles between adjusting lines and reformation baselines were measured. The axial, coronal, sagittal and multi-adjusting MPR images were graded according to the display of the ossicles. Then Ridit analyses and X2 test were performed. Results The demonstrating ratios of the panoramas of the malleus, incus, and stapes in one plane in multi-adjusting MPR images were 100% (50 middle ear) . The ratios were higher than those of axial (6 stapes, 0 malleus, 0 incus) , coronal (3 malleus, 0 incus, 0 stapes) , and sagittal images (0 malleus, 0 incus, 0 stapes) (Ridit analysis, P

Clinical value of ~(18)FDG PET-CT in the detection of Ivmoh node metastasis from advanced esophageal carcinoma / 中华放射肿瘤学杂志

Objective To evaluate the clinical value of 18floro-deoxyglucose positron emission tomography-CY(~(18)FDG PET-CT)in the diagnosis of lymph node metastasis from advanced esophageal carcinoma. Methods A prospective study is perfonued here to assess whether ~(18)FDG PET-CT can improve the diagnostic accuracy in lymph node metastasis for patients with advanced esophageal carcinoma.Thirty patients had undergone esophagectomy with extensive lymph node dissection.PET-CT findings were compared with that d CT with pathological finding as the final say.Results All patients were operated successfully without peri-operative complications.The pathological examination conformed metastasis in 22 patients and 49 out of 243 excised lymph nodes.In CT analysis,the sensitivity was 40.8%,specificity was 96.9%,with a diagnostic accuracy of 85.6%, The positive and negative predictive value was 76.9%,86.4% respectively;PET-CT resulted in a sensitivity of 93.9%,specificity of 91.2%,accuracy of 91.8%.The positive predictive value was 73.0% and negative predictive value was 98.3%,The difference of sensitivity(P＜0.001),accuracy(P＜0.05)and negative predictive value between the two radiological modalities was statistically significant(P＜0.001).Conclusions With a high sensitivity and accuracy in the diagnosis of lymph node metastasis,PET-CT appears necessary in preoperative examination for advanced esophageal carcinoma in the hope that surgical treatment be guided by the results of PET-CT,especially for the elder patients with poor pulmonary function or heart or brain complications. Moreover,it could be used as the basis of the conformal radiation therapy planning for inoperable patients.