Aggressive vertebral hemangiomas contain no adipose tissue resulting in thoracic spine kyphosis: A case report.

RATIONALE: Aggressive vertebral hemangiomas (AVHs) destroy continuous vertebral bodies and intervertebral discs and resulting in spinal kyphosis is extremely rare. The very aggressive behavior was attributable to its significant vascular component and contained no adipose tissue. PATIENT CONCERNS: We report a case of thoracic spine kyphosis of AVHs with multiple vertebral bodies and intervertebral disc destruction in a 45-year-old woman. DIAGNOSES: Based on the imaging studies, the patient underwent surgical removal of this lesion and spinal reconstruction. Histopathology consistent with vertebral hemangioma and contained no adipose. INTERVENTIONS: The patient underwent surgical removal of the lesion and spinal reconstruction. After subperiosteal dissection of the paraspinal muscles and exposure of the laminae, the laminae of the T5-7 vertebrae were removed and exposing the lesion. The lesion was soft and showed cystic changes, completely curetted and autogenous bone was implanted. Vertebroplasty was performed through T3-T9 pedicles bilaterally. Pedicle screw fixation was performed for segmental fixation and fusion. OUTCOMES: After 9 days of operation, the incision healed cleanly and free of pain. She was discharged in good general condition. The patient remained asymptomatic after follow-up 6 months of postoperative. LESSONS: AVHs destroy multiple vertebral bodies and intervertebral discs and resulting in spinal kyphosis is extremely rare.

The Origin and Course of the Blood Supply to the Lower Eyelid Orbital Fat: Anatomical Study and Clinical Significance.

PURPOSE: The aim of this study is to investigate the origin and course of the orbital fat arterial supply in the lower eyelid using traditional anatomy and three-dimensional computed tomography (CT). METHODS: Twenty-seven cadaver heads were infused with mercury sulfide contrast media through the ophthalmic artery, maxillary artery, transverse facial artery, and facial artery. CT images were obtained after contrast agent injection, three-dimensional CT scans were reconstructed, and the cadaver heads were dissected. RESULTS: Forty-five qualified hemifaces showed that the orbital fat arterial supply in the lower eyelid originates primarily from the inferomedial muscular trunk (IMT) of the ophthalmic artery and the orbital branch of the infraorbital artery. The medial branch of the IMT terminated at the medial fat pad (35.6%) or the orbital floor (64.4%). The lateral branch terminated at the inferior oblique (IO) muscle (28.9%) or the central and lateral fat pads (17.8%). In 53.3%, the lateral branch extended to the anterior part of the lateral fat pad and terminated in the orbital wall or the zygomaticoorbital foramina. The orbital branch of the infraorbital artery coursed between the orbital floor and the orbital fat, providing supply to the IO muscle, inferior rectus (IR) muscle, nasolacrimal duct, and orbital fat. CONCLUSION: This study elucidated the origin and course of the orbital fat arterial supply in the lower eyelid, which may help to avoid reducing the blood supply of the orbital fat pedicles during surgery. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Discovery of metal-binding proteins by thermal proteome profiling.

Metal-binding proteins (MBPs) have various and important biological roles in all living species and many human diseases are intricately linked to dysfunctional MBPs. Here, we report a chemoproteomic method named 'metal extraction-triggered agitation logged by thermal proteome profiling' (METAL-TPP) to globally profile MBPs in proteomes. The method involves the extraction of metals from MBPs using chelators and monitoring the resulting protein stability changes through thermal proteome profiling. Applying METAL-TPP to the human proteome with a broad-spectrum chelator, EDTA, revealed a group of proteins with reduced thermal stability that contained both previously known MBPs and currently unannotated MBP candidates. Biochemical characterization of one potential target, glutamine-fructose-6-phosphate transaminase 2 (GFPT2), showed that zinc bound the protein, inhibited its enzymatic activity and modulated the hexosamine biosynthesis pathway. METAL-TPP profiling with another chelator, TPEN, uncovered additional MBPs in proteomes. Collectively, this study developed a robust tool for proteomic discovery of MBPs and provides a rich resource for functional studies of metals in cell biology.

Intratumoral and peritumoral CT radiomics in predicting prognosis in patients with chondrosarcoma: a multicenter study.

OBJECTIVE: To evaluate the efficacy of the CT-based intratumoral, peritumoral, and combined radiomics signatures in predicting progression-free survival (PFS) of patients with chondrosarcoma (CS). METHODS: In this study, patients diagnosed with CS between January 2009 and January 2022 were retrospectively screened, and 214 patients with CS from two centers were respectively enrolled into the training cohorts (institution 1, n = 113) and test cohorts (institution 2, n = 101). The intratumoral and peritumoral radiomics features were extracted from CT images. The intratumoral, peritumoral, and combined radiomics signatures were constructed respectively, and their radiomics scores (Rad-score) were calculated. The performance of intratumoral, peritumoral, and combined radiomics signatures in PFS prediction in patients with CS was evaluated by C-index, time-dependent area under the receiver operating characteristics curve (time-AUC), and time-dependent C-index (time C-index). RESULTS: Eleven, 7, and 16 features were used to construct the intratumoral, peritumoral, and combined radiomics signatures, respectively. The combined radiomics signature showed the best prediction ability in the training cohort (C-index, 0.835; 95%; confidence interval [CI], 0.764-0.905) and the test cohort (C-index, 0.800; 95% CI, 0.681-0.920). Time-AUC and time C-index showed that the combined signature outperformed the intratumoral and peritumoral radiomics signatures in the prediction of PFS. CONCLUSION: The CT-based combined signature incorporating intratumoral and peritumoral radiomics features can predict PFS in patients with CS, which might assist clinicians in selecting individualized surveillance and treatment plans for CS patients. CRITICAL RELEVANCE STATEMENT: Develop and validate CT-based intratumoral, peritumoral, and combined radiomics signatures to evaluate the efficacy in predicting prognosis of patients with CS. KEY POINTS: • Reliable prognostic models for preoperative chondrosarcoma are lacking. • Combined radiomics signature incorporating intratumoral and peritumoral features can predict progression-free survival in patients with chondrosarcoma. • Combined radiomics signature may facilitate individualized stratification and management of patients with chondrosarcoma.

Response of vertebral fractures to treatment with denosumab in a patient with postpartum osteoporosis: a case report and literature review.

Postpartum osteoporosis (PO) is a rare condition characterized by low bone mineral density (BMD) and an increased risk of vertebral fragility fracture. We encountered a 34-year-old woman who developed back pain 1 week after delivery. Magnetic resonance imaging of the lumbar spine revealed three vertebral compression fractures. Pretreatment BMD evaluation by dual-energy X-ray absorptiometry revealed a low T-score and Z-score (-2.0 and -2.0, respectively; BMD, 0.876 g/cm2) in the affected region of the spine. The patient was diagnosed with PO and treated with subcutaneous injection of denosumab 60 mg (Prolia; Amgen, Inc., Thousand Oaks, CA, USA) every 6 months. After two treatments, the BMD had significantly increased and the back pain was improved; the patient therefore decided to terminate the treatment. Two months later, her back pain worsened and BMD decreased as measured by dual-energy X-ray absorptiometry examination of the lumbar spine. Therefore, the patient resumed treatment with denosumab, and the BMD of the lumbar spine increased after another two treatments. Therefore, we consider denosumab to be promising in the management of PO with respect to increased BMD and decreased pain.

Primary bone tumor detection and classification in full-field bone radiographs via YOLO deep learning model.

OBJECTIVES: Automatic bone lesions detection and classifications present a critical challenge and are essential to support radiologists in making an accurate diagnosis of bone lesions. In this paper, we aimed to develop a novel deep learning model called You Only Look Once (YOLO) to handle detecting and classifying bone lesions on full-field radiographs with limited manual intervention. METHODS: In this retrospective study, we used 1085 bone tumor radiographs and 345 normal bone radiographs from two centers between January 2009 and December 2020 to train and test our YOLO deep learning (DL) model. The trained model detected bone lesions and then classified these radiographs into normal, benign, intermediate, or malignant types. The intersection over union (IoU) was used to assess the model's performance in the detection task. Confusion matrices and Cohen's kappa scores were used for evaluating classification performance. Two radiologists compared diagnostic performance with the trained model using the external validation set. RESULTS: In the detection task, the model achieved accuracies of 86.36% and 85.37% in the internal and external validation sets, respectively. In the DL model, radiologist 1 and radiologist 2 achieved Cohen's kappa scores of 0.8187, 0.7927, and 0.9077 for four-way classification in the external validation set, respectively. The YOLO DL model illustrated a significantly higher accuracy for intermediate bone tumor classification than radiologist 1 (95.73% vs 88.08%, p = 0.004). CONCLUSIONS: The developed YOLO DL model could be used to assist radiologists at all stages of bone lesion detection and classification in full-field bone radiographs. KEY POINTS: • YOLO DL model can automatically detect bone neoplasms from full-field radiographs in one shot and then simultaneously classify radiographs into normal, benign, intermediate, or malignant. • The dataset used in this retrospective study includes normal bone radiographs. • YOLO can detect even some challenging cases with small volumes.

Atypical aggressive vertebral hemangioma of the sacrum with postoperative recurrence: A case report.

BACKGROUND: Aggressive vertebral hemangioma (VH) is an uncommon lesion in the adult population. The vast majority of aggressive VHs have typical radiographic features. However, preoperative diagnosis of atypical aggressive VH may be difficult. Aggressive VHs are likely to recur even with en bloc resection. CASE SUMMARY: A 52-year-old woman presented with a 3-mo history of numbness and pain in her right lower extremity. Physical examination showed sacral tenderness and limited mobility, and the muscle strength was grade 4 in the right digital flexor. Computed tomography revealed osteolytic bone destruction from S1 to S2. Magnetic resonance imaging (MRI) showed that the mass was compressing the dural sac; it was heterogeneously hypointense on T1-weighted MRI and hyperintense on T2-weighted MRI, and gadolinium contrast enhancement showed that the tumor was heterogeneously enhanced and invading the vertebral endplate of S1. The patient developed progressive back pain and numbness in the bilateral extremities 6 mo postoperatively, and MRI examination showed recurrence of the mass. The mass was larger in size than before the operation, and it was extending into the spinal canal. CONCLUSION: The radiographic findings of atypical aggressive VH include osteolytic vertebral bone destruction, extension of the mass into the spinal canal, and heterogeneous signal intensity on T1-, T2-, and enhanced T1-weighted MRI. These characteristics make preoperative diagnosis difficult, and biopsy is necessary to verify the lesion. Surgical decompression and gross total resection are recommended for treatment of aggressive VH. However, recurrence is inevitable in some cases.

Periosteal chondroma of the rib: A case report.

BACKGROUND: Periosteal chondroma is a very rare benign tumor that develops adjacent to the cortical surface of bone and beneath the periosteal membrane. Periosteal chondroma of the rib is an extremely rare entity. CASE SUMMARY: The patient was a 43-year-old man who had been incidentally found to have a mediastinal mass 1 mo earlier. Plain computed tomography showed a lobulated soft tissue mass on the right side of the T4/5 vertebra that measured about 47 mm × 28 mm in the transverse view and contained diffuse stippled calcification. The mass caused cortical scalloping of the right fourth rib and marginal bone sclerosis. Enhanced computed tomography showed mild enhancement of the mass. Magnetic resonance imaging showed a lobulated mass on the right side of the thoracic vertebra with long TI and T2 signals, mottling, and patchy long T1 and short T2 signals inside. The lesion had a hypointense rim. Enhanced magnetic resonance imaging showed enhancement predominantly at the periphery of the tumor. The tumor was approached through a right posterolateral thoracotomy, and parts of the fourth and fifth ribs were excised with the tumor. Postoperative pathological analysis revealed periosteal chondroma of the rib. CONCLUSION: Periosteal chondroma of the rib has a low incidence and typical imaging manifestations. Understanding its imaging features is helpful to ensure a correct preoperative diagnosis.

Giant cell tumors of the mobile spine with invasion of adjacent vertebrae: an unusual imaging finding.

BACKGROUND: Giant cell tumors of the mobile spine invasion of the adjacent vertebrae are an ignored imaging finding. METHODS: Nine patients with giant cell tumors of the mobile spine with invasion of the adjacent vertebrae confirmed by pathology were enrolled. Eight patients had pure giant cell tumors (GCTs), while one patient also had an aneurysmal bone cyst. All patients underwent conventional computed tomography, three-dimensional reconstruction, and conventional magnetic resonance imaging, while seven patients also underwent post-contrast magnetic resonance imaging. RESULTS: All patients showed GCTs of the mobile spine that arose from the vertebral body and extended to the vertebral arch. The tumors showed soft-tissue attenuation with no evidence of a mineralized matrix. Pathological fracture was seen in five patients. The margin of the original tumor showed partial sclerosis in four patients and involved an adjacent vertebral body with a sclerotic rim in two patients. The tumors showed a homogeneous and similar signal intensity to the normal spinal cord on T1WI (T1-weighted image) in five patients. The cystic area of the tumors was hyperintense on T2WI in the remaining four patients, while one patient showed hemorrhage that was hyperintense on T1WI. The solid components of the GCTs show marked enhancement in all cases, while the cystic area of the tumors was observed without enhancement on contrast-enhanced images in four patients. Bone destruction of the adjacent vertebral body showed a homogeneous signal on T1WI and T2WI and marked enhancement on contrast-enhanced images. CONCLUSIONS: Giant cell tumors of the mobile spine with invasion into adjacent vertebrae are an unusual imaging finding. Radiologists should be familiar with this imaging characteristic.

Humoral immune response to circulating SARS-CoV-2 variants elicited by inactivated and RBD-subunit vaccines.

SARS-CoV-2 variants could induce immune escape by mutations on the receptor-binding domain (RBD) and N-terminal domain (NTD). Here we report the humoral immune response to circulating SARS-CoV-2 variants, such as 501Y.V2 (B.1.351), of the plasma and neutralizing antibodies (NAbs) elicited by CoronaVac (inactivated vaccine), ZF2001 (RBD-subunit vaccine) and natural infection. Among 86 potent NAbs identified by high-throughput single-cell VDJ sequencing of peripheral blood mononuclear cells from vaccinees and convalescents, near half anti-RBD NAbs showed major neutralization reductions against the K417N/E484K/N501Y mutation combination, with E484K being the dominant cause. VH3-53/VH3-66 recurrent antibodies respond differently to RBD variants, and K417N compromises the majority of neutralizing activity through reduced polar contacts with complementarity determining regions. In contrast, the 242-244 deletion (242-244Δ) would abolish most neutralization activity of anti-NTD NAbs by interrupting the conformation of NTD antigenic supersite, indicating a much less diversity of anti-NTD NAbs than anti-RBD NAbs. Plasma of convalescents and CoronaVac vaccinees displayed comparable neutralization reductions against pseudo- and authentic 501Y.V2 variants, mainly caused by E484K/N501Y and 242-244Δ, with the effects being additive. Importantly, RBD-subunit vaccinees exhibit markedly higher tolerance to 501Y.V2 than convalescents, since the elicited anti-RBD NAbs display a high diversity and are unaffected by NTD mutations. Moreover, an extended gap between the third and second doses of ZF2001 leads to better neutralizing activity and tolerance to 501Y.V2 than the standard three-dose administration. Together, these results suggest that the deployment of RBD-vaccines, through a third-dose boost, may be ideal for combating SARS-CoV-2 variants when necessary, especially for those carrying mutations that disrupt the NTD supersite.

Extraosseous spinal epidural plasmocytoma associated with multiple myeloma: Two case reports.

BACKGROUND: Multiple myeloma is a malignant hematological disease characterized by proliferation of monoclonal plasma cells mainly in the bone marrow. Extraosseous epidural plasmacytoma associated with myeloma arises from lymphoid tissue in the epidural space without focal vertebral involvement, and is rare. CASE SUMMARY: A 52-year-old woman was diagnosed with kappa subtype nonsecretory multiple myeloma and presented with bilateral arm weakness 11 mo after completing multiple courses of chemotherapy. Spinal magnetic resonance imaging (MRI) showed a posterior C7-T3 epidural mass with spinal cord compression. After five courses of chemotherapy, follow-up MRI showed resolution of cord compression. A 54-year-old man presented with paraplegia 15 mo after a diagnosis of IgD kappa subtype multiple myeloma and completing multiple courses of chemotherapy. He underwent Th11 and L1 laminectomies for tumor resection because MRI showed an epidural mass causing cord compression. His-topathologic examination was consistent with IgD multiple myeloma. The patients have currently survived for 33 mo and 19 mo, respectively. CONCLUSION: Isolated extraosseous epidural plasmacytoma associated with multiple myeloma without bony involvement is difficult to diagnose by imaging. Definitive diagnosis requires pathological and immunohistochemical examination.

A CT-based radiomics nomogram for differentiation of lympho-associated benign and malignant lesions of the parotid gland.

OBJECTIVES: Preoperative differentiation between benign lymphoepithelial lesion (BLEL) and mucosa-associated lymphoid tissue lymphoma (MALToma) in the parotid gland is important for treatment decisions. The purpose of this study was to develop and validate a CT-based radiomics nomogram combining radiomics signature and clinical factors for the preoperative differentiation of BLEL from MALToma in the parotid gland. METHODS: A total of 101 patients with BLEL (n = 46) or MALToma (n = 55) were divided into a training set (n = 70) and validation set (n = 31). Radiomics features were extracted from non-contrast CT images, a radiomics signature was constructed, and a radiomics score (Rad-score) was calculated. Demographics and CT findings were assessed to build a clinical factor model. A radiomics nomogram combining the Rad-score and independent clinical factors was constructed using multivariate logistic regression analysis. The performance levels of the nomogram, radiomics signature, and clinical model were evaluated and validated on the training and validation datasets, and then compared among the three models. RESULTS: Seven features were used to build the radiomics signature. The radiomics nomogram incorporating the clinical factors and radiomics signature showed favorable predictive value for differentiating parotid BLEL from MALToma, with AUCs of 0.983 and 0.950 for the training set and validation set, respectively. Decision curve analysis showed that the nomogram outperformed the clinical factor model in terms of clinical usefulness. CONCLUSIONS: The CT-based radiomics nomogram incorporating the Rad-score and clinical factors showed favorable predictive efficacy for differentiating BLEL from MALToma in the parotid gland, and may help in the clinical decision-making process. KEY POINTS: • Differential diagnosis between BLEL and MALToma in parotid gland is rather difficult by conventional imaging modalities. • A radiomics nomogram integrated with the radiomics signature, demographics, and CT findings facilitates differentiation of BLEL from MALToma with improved diagnostic efficacy.

Compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition: A case report and review of literature.

RATIONALE: Compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition is a rare condition. Vertebral body compression fracture and high serum progesterone lead to extraosseous hemangioma enlargment cause narrowing the spinal canal which contribute to compressive myelopathy relate to pregnancy. PATIENT CONCERNS: We report a case of compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition in a 35-year-old woman. The patient complained unable to walk and experienced intense pain in the back. DIAGNOSIS: Based on the clinical features and imaging studies, the patient underwent a T4-T6 laminectomy. Histopathology consistent with vertebral hemangioma. INTERVENTIONS: The patient underwent laminectomy for decompression. After subperiosteal dissection of the paraspinal muscles and exposure of the laminae, there was no involvement of the lamina by the tumor. The epidural tumor was removed through the spaces lateral to the thecal sac. Vertebroplasty was performed through T5 pedicles bilaterally and 7 ml of polymethylmethacrylate (PMMA) cement was injected. T4-T6 pedicle screw fixation was performed for segmental fixation and fusion. OUTCOMES: Six months after resection of the tumor the patient remained asymptomatic. She reported no low back pain and had returned to her normal daily activities, with no radiographic evidence of recurrence on MRI. Physical examination revealed that superficial and deep sensation was restored to normal levels in the lower extremities. LESSONS: The occurrence of compressive myelopathy of pregnancy related vertebral hemangiomas is quite unusual. It can lead to serious neurologic deficits if not treated immediately. So, prompt diagnosis is important in planning optimal therapy and preventing morbidity for patients.

Intradural cervical chordoma with diffuse spinal leptomeningeal spread: case report and review of the literature.

PURPOSE: Chordoma is a low-grade malignant bone tumor derived from embryonic notochord remnants along the axial skeleton. About 50% of chordomas occur in the sacral vertebrae and 35% in the skull base. Most chordomas are extradural and cause extensive bone destruction. Intradural spinal tumors without bone involvement are rare. METHODS: We herein describe the clinical features of a patient with a chordoma as well as the imaging and pathological manifestations of the tumor. RESULTS: We encountered an unusual presentation of a C6 and C7 spinal intradural chordoma in a 23-year-old man. He presented with a 5-day history of discomfort over the lumbosacral region. Magnetic resonance imaging and enhanced scanning of the cervical spine showed an intradural soft tissue mass at C6 and C7 and linear enhancement of the spinal meninges. The tumor was excised because the patient had been previously misdiagnosed with an intraspinal neurogenic tumor with spinal meningitis. Postoperative pathological examination confirmed the diagnosis of chordoma. On postoperative day 7, the patient underwent brain magnetic resonance imaging because of severe headache. The images showed multiple soft tissue nodules in the skull base cistern. To the best of our knowledge, this is the first case report of an entirely extraosseous and spinal intradural chordoma with diffuse spinal leptomeningeal spread. The patient died 2 months postoperatively. CONCLUSIONS: An intradural spinal chordoma is difficult to distinguish from a neurogenic tumor by imaging. When the lesion is dumbbell-shaped, it is easily misdiagnosed as a schwannoma. In the present case, the tumor was intradural and located at the level of the C6 and C7 vertebrae. Preoperative diagnosis was difficult, and the final diagnosis required pathological examination.

Spinal Epidural Cavernous Hemangioma: A Clinical Series of 7 Patients.

OBJECTIVE: To investigate imaging characteristics of spinal epidural cavernous hemangiomas (ECHs) and improve understanding of this rare disease. METHODS: This retrospective study included 7 cases of ECH, confirmed with surgical pathology and imaging. All patients underwent computed tomography and conventional magnetic resonance imaging. One patient underwent diffusion-weighted imaging. RESULTS: ECH originated from vertebrae with coarsened trabeculae in 5 patients. Among these, 1 tumor was mainly in the intervertebral foramen and paravertebral space, 2 extended to the intraspinal and paravertebral spaces and appeared dumbbell-shaped, and 2 were located in the intraspinal space. Purely epidural hemangiomas were present in 2 patients; 1 of these patients had adjacent bony erosion. Epidural hemangiomas were isointense in 6 patients and hyperintense in 1 patient on T1-weighted images; lesions were hyperintense on T2-weighted images in all 7 patients. Peripheral fat was present in 4 ECHs; 2 were of vertebral origin, and 2 were of epidural space origin. In the patient who underwent diffusion-weighted imaging, the lesion showed restricted diffusion. The affected vertebra had coarsened trabeculae, which may be a critical finding for differentiating ECHs of vertebral origin from foraminal nerve sheath tumors. Peripheral fat around hemangiomas of vertebral origin and primary epidural space hemangiomas indicates chronicity. CONCLUSIONS: ECHs are classified either as epidural hemangiomas of vertebral origin or as primary epidural hemangiomas. Awareness of imaging characteristics of ECHs may facilitate diagnosis and treatment of these lesions.

Lack of association between SLC5A7 polymorphisms and Tourette syndrome in a Chinese Han population.

Although Tourette syndrome (TS) is a chronic neuropsychiatric disorder whose pathogenesis remains unclear, genetic factors play an important role in the occurrence and development. A variety of studies have been shown that the candidate genes related to cholinergic neurons may be associated with the onset of TS. To investigate the association between the SLC5A7 polymorphisms and Tourette syndrome (TS) in the Chinese Han population, the SNP rs1013940, rs2433718, and rs4676169 were genotyped in 401 TS trios and 400 controls. The transmission disequilibrium test (TDT) and haplotype relative risk (HRR) compared genetic distributions of trios, while the chi-square test compared patients and controls. However, no transmission disequilibrium was found between the three SLC5A7 SNPs and TS. Therefore, we think that this gene may not be the main risk factor on the onset of TS. However, these results should be further validated in different populations.

Low-grade chondrosarcoma of the cricoid cartilage: a case report and review of the literature.

We report the case of a 60-year-old man with a 12-day history of vomiting whenever he had a meal. Computed tomography revealed a calcified mass in the right cricoid cartilage with intraluminal and extraluminal extension. The patient underwent surgical resection of the trachea with end-to-end anastomosis. Pathological examination of the surgical specimen showed a low-grade chondrosarcoma. Eighteen months after surgery, the patient is alive and disease-free.

A Study of Electrochemical Machining of Ti-6Al-4V in NaNO3 solution.

The titanium alloy Ti-6Al-4V is used in many industries including aviation, automobile manufacturing, and medical equipment, because of its low density, extraordinary corrosion resistance and high specific strength. Electrochemical machining (ECM) is a non-traditional machining method that allows applications to all kinds of metallic materials in regardless of their mechanical properties. It is widely applied to the machining of Ti-6Al-4V components, which usually takes place in a multicomponent electrolyte solution. In this study, a 10% NaNO3 solution was used to make multiple holes in Ti-6Al-4V sheets by through-mask electrochemical machining (TMECM). The polarization curve and current efficiency curve of this alloy were measured to understand the electrical properties of Ti-6Al-4V in a 10% NaNO3 solution. The measurements show that in a 10% NaNO3 solution, when the current density was above 6.56 A·cm-2, the current efficiency exceeded 100%. According to polarization curve and current efficiency curve, an orthogonal TMECM experiment was conducted on Ti-6Al-4V. The experimental results suggest that with appropriate process parameters, high-quality holes can be obtained in a 10% NaNO3 solution. Using the optimized process parameters, an array of micro-holes with an aperture of 2.52 mm to 2.57 mm and maximum roundness of 9 µm were produced using TMECM.