Quality evaluation of ultra-thin samples: Application to graphene.

Many new materials emerging are strictly two dimensional (2D), often only one or two monolayers thick. They include transition metal dichalcogenides, such as MoS2 , and graphene. Graphene in particular appears to have many potential applications. Typically the crystalline film without contamination is of interest. Therefore, a reliable method is needed to routinely evaluate the quality of the synthesized samples. Here, we present one such candidate method that utilizes standard electron diffraction and low/medium magnification imaging in a rudimentary transmission electron microscope. The electron irradiation dose is very low thus reducing electron irradiation damage of the investigated samples. As an example, the method was applied to the evaluation of as-grown graphene sample quality and a study on heating-induced change in graphene. It can be used to evaluate the volume and areal ratio of crystalline to noncrystalline component. The method is amiable to automated film quality evaluation.

Validity of the dipole approximation in TEM-EELS studies.

Nondipole effects in electron energy-loss spectroscopy are evaluated in terms of deviation of the inelastic scattering from a Lorentzian angular distribution, which is assumed in established procedures for plural-scattering deconvolution, thickness measurement, and Kramers-Kronig analysis. The deviation appears to be small and may be outweighed by the effect of plural (elastic + inelastic) scattering, which is not removed by conventional deconvolution methods. In the core-loss region of the spectrum, non-Lorentzian behaviour stems from a reduction of the generalized oscillator strength from its optical value and (for energies far above an ionization threshold) formation of a Bethe-ridge angular distribution. At incident energies above 200 keV, retardation effects further distort the angular dependence, even for core losses just above threshold. With an on-axis collection aperture, non-dipole effects are masked by the rapid falloff of intensity with scattering angle, but they may become important for off-axis measurements. Near-edge fine structure is sensitive to nondipole effects but these can be minimized by use of an angle-limiting collection aperture.

Clinicopathologic features and treatment of postirradiation sarcoma of bone and soft tissue.

BACKGROUND AND OBJECTIVES: An analysis of the clinicopathologic features and treatment of patients with postirradiation sarcoma of bone and soft tissue was performed to guide modern evaluation and management. METHODS: A retrospective analysis of 135 sarcomas in 130 patients was performed. RESULTS: The mean age of the 130 patients was 48 years, and there was a female predominance because of irradiation for carcinomas of the breast and uterus. Indication for irradiation was a soft tissue lesion (such as lymphoma or breast cancer) in 58.5% of patients and a bone lesion (such as giant cell tumor or fibrous dysplasia) in 41.5%. The latent period (interval between irradiation and discovery of the sarcoma) ranged from 4-55 years (mean, 17 years). Of the lesions, 74% were stage IIB (high-grade extra-compartmental) and 24% were stage III (metastases). Ninety-four patients received their treatment at our institution. Of the 61 patients with resectable disease, 49 had amputations and 12 had limb salvage procedures. The 5-year cumulative survival rate was 68.2% for patients with peripheral (extremities, including proximal femur and hip) resectable lesions and 27.3% for patients with central (pelvis, head/neck, and ribs) resectable lesions. The local recurrence rate correlated with the surgical margin achieved: intralesional, 73%, marginal, 64%, and wide, 23%. CONCLUSIONS: The prognosis for patients with peripheral resectable postirradiation sarcomas is good if a wide surgical margin can be achieved. This group of patients should be treated aggressively because they have a new cancer.

Primary chondrosarcoma of long bones and limb girdles.

BACKGROUND: Chondrosarcomas are common solid malignant tumors of bone, second in incidence only to osteosarcomas. The biologic evolution of chondrosarcomas is slow, requiring long follow-up intervals for meaningful survival analysis. METHODS: This study describes the clinicopathologic profiles of 344 patients, 194 male and 150 female (M:F, 1.3:1.0), with primary chondrosarcoma of long bones and limb girdles seen at 1 institution over a period of 80 years. RESULTS: The average age at presentation was 46 years (range, 5-82 years). The pelvis was the most common location (1.7% of all patients). Local pain was the most frequently reported initial symptom (81.4%). Survival analysis was limited to 233 patients whose primary treatment was given at the Mayo Clinic. All 233 patients had potential follow-up of at least 5 years. The overall 5-year survival rate was 77% (the expected rate was 96%). Local recurrence developed in 19.7% of patients and metastatic lesions in 13.7%. The recurrence rate was higher for tumors of the shoulder and pelvis than for tumors of long bones. Radiographically, chondrosarcomas had a characteristic appearance, including a combination of bone expansion and cortical thickening. Entering the tumor at surgery increased the risk of local recurrence. Histologic tumor grade was an important predictor of local recurrence and metastasis. CONCLUSIONS: With adequate initial surgical intervention, chondrosarcoma is primarily a local disease with a low metastatic rate.

Screen-film versus computed radiography imaging of the hand: a direct comparison.

OBJECTIVE: Computed radiography of the musculoskeletal system has the potential to become a powerful tool in the practice of diagnostic radiology. It addresses many of the geographic and film-distribution concerns facing diagnostic imaging. We undertook this study to compare and document the quality of computed radiographs and conventional screen-film images before widespread implementation. MATERIALS AND METHODS: We evaluated clinical images using direct comparison. Bilateral hand images from 50 patients were scored independently by six musculoskeletal radiologists. In each case one hand was imaged with a conventional screen-film technique and the other with computed radiography. Images were masked to eliminate as much bias as possible. The numeric scores assigned to the images by the observers were analyzed using Student's t test. RESULTS: Computed radiographs were judged with statistical significance to be better than conventional screen-film images in all features judged by the observers, including bone cortex, bone trabeculae, corticomedullary junction, distal phalangeal tuft, soft tissues, fat planes, bone-soft-tissue interface, and overall contrast and density. CONCLUSION: The statistically significant determination that the image quality of computed radiographs is at least as good as screen-film images allows confident use of computed radiography and enables radiologists to take advantage of its many other practical capabilities related to image distribution, storage, cost, and geographic coverage without sacrificing image quality.

Epithelioid hemangioendothelioma of bone.

Epithelioid hemangioendothelioma of bone is a rare tumor of vascular origin. A series of 40 cases from the Mayo Clinic files was studied to define the pathologic features of this disease and to evaluate any histologic or clinical factor influencing outcome. More than 50% of the tumors were multicentric, with a predilection for bones of a particular anatomical area. In this series, patients with multifocal tumors did not have a better prognosis than those with unicentric disease. We could not predict the outcome of cases on the basis of the histologic features. Visceral involvement was the most important criterion in predicting prognosis. Resection is still the primary treatment for these tumors. Radiotherapy may be useful for surgically inaccessible tumors. Too few patients have received adjuvant chemotherapy to evaluate its usefulness in this setting.

Elastofibroma dorsi: radiologic findings in 12 patients.

OBJECTIVE: We report radiologic findings in 12 patients with elastofibroma dorsi to heighten radiologist awareness of the imaging characteristics of these benign, often asymptomatic lesions. Because these lesions can usually be diagnosed on the basis of their imaging characteristics, increased awareness of these characteristics will decrease misdiagnosis of these lesions as malignancies and avoid unnecessary biopsies and surgeries. MATERIALS AND METHODS: We retrospectively reviewed the radiology and pathology of nine patients with surgically excised elastofibromas and the radiology of three patients with radiologically diagnosed elastofibromas. RESULTS: Twenty-one elastofibromas were imaged in 12 patients. Female-to-male ratio was 5:1; mean age was 65 years old. Of the nine patients in whom both sides of the chest wall were imaged, all (100%) had bilateral elastofibromas. Nineteen elastofibromas (90%) had the typical CT and MR appearances described in the literature: a poorly circumscribed, heterogeneous soft-tissue mass, with tissue of attenuation or signal intensity similar to that of skeletal muscle interlaced with strands of fat. One elastofibroma imaged twice over a 4-year period showed interval growth. All elastofibromas were sub- or infrascapular or in both locations. Of the 21 elastofibromas imaged, only four were perceived by the initial interpreting radiologist, and of these, only one was correctly diagnosed. CONCLUSION: Our study shows that many radiologists may not be aware of the diagnosis of elastofibroma, as few of the cases in our series were perceived or correctly diagnosed by the interpreting radiologist. Our cases show many of the classic findings of elastofibromas described in the literature. In addition, our series shows that elastofibromas are commonly bilateral, a feature that has not been strongly emphasized in the literature but one that is helpful in making the radiologic diagnosis. The finding of a similar contralateral lesion, when present, virtually eliminates malignancy from the differential diagnosis and further supports the presumptive diagnosis of elastofibromas. Increased awareness of the characteristic appearance and location of these benign, often asymptomatic lesions will increase radiologic diagnosis, decrease the need for biopsy, and decrease surgical removal of elastofibromas as presumed malignancies.

Low grade central osteogenic sarcoma. A long-term followup of 20 patients.

Osteogenic sarcoma is a heterogeneous family of tumors that has a variable biologic behavior. Low grade central osteogenic sarcoma is an uncommon form that is characterized by a long premorbid history and is compatible with prolonged survival after treatment. Twenty cases of low grade central osteosarcoma with long-term followup (16 [2.5-48] years) were studied retrospectively. The age distribution was broad (range, 15-83 years). All tumors arose in the lower limb. The primary symptom was pain; mean duration was 44 months (range, 1-180 months). A diagnosis of low grade central osteosarcoma was made primarily for 11 patients. For 9 others, fibrous dysplasia (3), nonossifying fibroma (2), fibroma (1), chondromyxoid fibroma (1), chondrosarcoma (1), and simple bone cyst (1) were diagnosed initially. Intralesional surgery was associated with recurrence in every case. Radical margins were not associated with local recurrence. Four recurrences were higher grade and 1 was dedifferentiated. Three of 4 patients with metastases died of their disease. Five- and 10-year survival was 90% and 85%, respectively. Histology and radiology are complementary for confirming the diagnosis. Low grade central osteosarcoma seems to be controllable by surgery alone if at least wide margins are used.

The importance of bone biopsy in managing renal osteodystrophy.

A case is presented in which bone biopsy results helped to resolve not only difficult issues in the clinical management of the patient's renal osteodystrophy but also disruptive psychosocial problems surrounding her clinical course. The outcome was a satisfactory resolution based on rational medical treatment and directed supportive care. The presentation highlights important principles in the procurement, processing, and interpretation of the bone biopsy, while also addressing the importance of accurate diagnosis in facilitating the overall long-term management by the entire renal team.

Osteoblastoma: clinicopathologic study of 306 cases.

The clinical, radiologic, and pathologic features of 306 osteoblastomas were analyzed. Seventy-five were Mayo Clinic cases and 231 were from consultation files. Males outnumbered females two to one. The age range was 6 months to 75 years (mean age, 20.4 years). The vertebral column including the sacrum was the most frequent site (32%). Pain was the usual complaint and neurologic findings were associated with vertebral tumors. Although most tumors were well circumscribed, cortical expansion and destruction were common radiographic findings (39%), and 12% had features suggestive of malignancy. Large, epithelioid osteoblasts were seen in 24% and were the predominant cellular element in 10%. A distinctive epithelioid multifocal pattern was recognized. Recurrence rates were 16% (Mayo Clinic cases) and 21% (consultation cases). Tumors involving the central neuraxis were associated with greater morbidity and mortality. Aggressive behavior is within the biologic spectrum of osteoblastomas, and histopathology alone does not appear to be a reliable predictor of aggressiveness. The most important differential diagnosis is osteosarcoma.

Osteofibrous dysplasia: clinicopathologic study of 80 cases.

A thorough review of the clinical, radiologic, and histologic features of 80 cases of long bone osteofibrous dysplasia is presented. Of the six cases of osteofibrous dysplasia immunostained with a cytokeratin antibody, two were cytokeratin positive; however, the five cases of fibrous dysplasia that were stained were all negative. Follow-up (mean, 5.4 years; range, 1 month to 31 years) data were available for 41 cases (51%). From the consultation series nine of the 18 patients studied had recurrences, regardless of the different treatment regimens. The average recurrence interval in these patients was 2.7 years. Two patients had incomplete excision and six had biopsy only. All eight of these patients had residual tumors. Among the 16 Mayo Clinic patients, one had recurrence 5 years after the initial treatment. In two cases, 7-year-old and 6-year-old boys, histologic maturation to fibrous dysplasia was observed 4 and 10 years later, respectively. Adamantinoma has not developed in any of the 41 cases of osteofibrous dysplasia for which we have follow-up information. It seems clear that osteofibrous dysplasia does not progress to adamantinoma. Our study suggests that osteofibrous dysplasia is probably a variant of fibrous dysplasia, as demonstrated by the maturation of two lesions of osteofibrous dysplasia to fibrous dysplasia. Surgical treatment may be appropriate in cases with an extensive lesion, pseudoarthrosis, and accentuated tibial bowing. The overall prognosis is good, even with recurrence.

Treatment of giant-cell tumor of the pelvis.

Nineteen patients who had a giant-cell tumor of the pelvis were managed from 1944 through 1989. Thirteen of the patients were in the third or fourth decade of life. The ileum was involved in thirteen patients; the pubis, in two; the ischium, in three; and the pubis and ischium, in one. Five patients who had an initial Stage-II (active) lesion were managed with curettage; in one of the five, a local recurrence developed at twelve months, and the other four had no evidence of disease from nine to forty-six years after the curettage. Eight patients who had a Stage-III (aggressive) lesion were managed with resection of most of the lesion followed by curettage of any remaining positive margins; four of the eight also received adjuvant irradiation. None of the eight had a local recurrence; six had no evidence of disease from eight to twenty-seven years after the operation, one died because of a metastatic post-radiation sarcoma thirteen years after the operation, and one was asymptomatic but had pulmonary metastases three years after the operation. Four patients who had a Stage-III recurrent local tumor when they were first seen were managed with hemipelvectomy, wide resection, resection and curettage, and curettage and arthroplasty (one procedure each). Three had no evidence of disease seven to twenty years after the operation and one had died because of a post-radiation metastatic osteosarcoma eight years after the operation. Two patients who had Stage-III disease were managed with external beam radiation alone. One had no evidence of disease twenty-six years later. The other had a recurrence one year later, which was treated with additional irradiation; a second recurrence was treated with curettage and bone-grafting. Twenty-eight years after the initial radiation treatment, this patient had no evidence of disease. External beam irradiation was used for a total of eight patients; a post-radiation sarcoma developed in two.

Chondroblastoma.

Chondroblastoma of the bone is a benign tumor that has well-characterized radiographic and histologic features. It tends to affect the epiphyseal ends of long bones in men during the second and third decades of life. The tumor is located more frequently at other sites in older patients. The treatment of choice is complete curettage with bone grafting, which in our series provided local control in 82% of patients at 2 years' follow-up. Recurrent tumors usually can be treated in the same manner.

Interim results of a phase II multicenter clinical trial evaluating the activity of a therapeutic allogeneic melanoma vaccine (theraccine) in the treatment of disseminated malignant melanoma.

A total of 139 patients with disseminated malignant melanoma were enrolled in an uncontrolled Phase II trial evaluating the activity of Melacine, allogeneic vaccine incorporating Detox, immunologic adjuvant. Nineteen patients, including 18 with progressive disease, dropped out of the study prior to receiving one full vaccination course of five injections over 6 weeks. Disease presentation among study participants included skin or lymph nodes (34%), pulmonary (24%), visceral (34%), and no evidence of disease (NED) (7%). One documented metastatic site was seen in 41%, two sites in 24%, and three or more sites in 27% of the patients studied. Objective clinical response rates for evaluable patients were CR 3%, PR 5%, minor response 4%, stable 23%, and progressive disease 65%. Median survival from time of diagnosis for patients treated with Melacine is presently estimated at 23 months (45/139 patients censored). Median date from diagnosis of metastatic disease to study entry was 3 months. Side effects were generally mild to moderate with pain at injection site (37%), granulomas (13%), erythema (6%), and flu-like symptoms (14-29%) predominating. Precursor antimelanoma cytotoxic T cell (pre-CTL) titers, in comparison with prestudy evaluations, clearly increased in 42% of the patients evaluated. Significantly extended survival characteristics were observed among patients who displayed an expansion of a population of CD57, CD8 co-positive lymphocytes during therapy in comparison with those patients not displaying this peripheral blood lymphocyte (PBL) population expansion (34 mo vs. 12 mo, respectively, p = 0.04) and among those patients displaying disease stabilization or better as a clinical response (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)