Associative white matter tracts selectively predict sensorimotor learning.

Human learning varies greatly among individuals and is related to the microstructure of major white matter tracts in several learning domains, yet the impact of the existing microstructure of white matter tracts on future learning outcomes remains unclear. We employed a machine-learning model selection framework to evaluate whether existing microstructure might predict individual differences in learning a sensorimotor task, and further, if the mapping between tract microstructure and learning was selective for learning outcomes. We used diffusion tractography to measure the mean fractional anisotropy (FA) of white matter tracts in 60 adult participants who then practiced drawing a set of 40 unfamiliar symbols repeatedly using a digital writing tablet. We measured drawing learning as the slope of draw duration over the practice session and measured visual recognition learning for the symbols using an old/new 2-AFC task. Results demonstrated that tract microstructure selectively predicted learning outcomes, with left hemisphere pArc and SLF3 tracts predicting drawing learning and the left hemisphere MDLFspl predicting visual recognition learning. These results were replicated using repeat, held-out data and supported with complementary analyses. Results suggest that individual differences in the microstructure of human white matter tracts may be selectively related to future learning outcomes.

Associative white matter tracts selectively predict sensorimotor learning.

Human learning is a complex phenomenon that varies greatly among individuals and is related to the microstructure of major white matter tracts in several learning domains, yet the impact of the existing myelination of white matter tracts on future learning outcomes remains unclear. We employed a machine-learning model selection framework to evaluate whether existing microstructure might predict individual differences in the potential for learning a sensorimotor task, and further, if the mapping between the microstructure of major white matter tracts and learning was selective for learning outcomes. We used diffusion tractography to measure the mean fractional anisotropy (FA) of white matter tracts in 60 adult participants who then underwent training and subsequent testing to evaluate learning. During training, participants practiced drawing a set of 40 novel symbols repeatedly using a digital writing tablet. We measured drawing learning as the slope of draw duration over the practice session and visual recognition learning as the performance accuracy in an old/new 2-AFC recognition task. Results demonstrated that the microstructure of major white matter tracts selectively predicted learning outcomes, with left hemisphere pArc and SLF 3 tracts predicting drawing learning and the left hemisphere MDLFspl predicting visual recognition learning. These results were replicated in a repeat, held-out data set and supported with complementary analyses. Overall, results suggest that individual differences in the microstructure of human white matter tracts may be selectively related to future learning outcomes and open avenues of inquiry concerning the impact of existing tract myelination in the potential for learning. Significance statement: A selective mapping between tract microstructure and future learning has been demonstrated in the murine model and, to our knowledge, has not yet been demonstrated in humans. We employed a data-driven approach that identified only two tracts, the two most posterior segments of the arcuate fasciculus in the left hemisphere, to predict learning a sensorimotor task (drawing symbols) and this prediction model did not transfer to other learning outcomes (visual symbol recognition). Results suggest that individual differences in learning may be selectively related to the tissue properties of major white matter tracts in the human brain.

Periosteal chondroid tumors: radiologic evaluation with pathologic correlation.

OBJECTIVE: The purpose of this study was to determine whether the imaging features of periosteal chondroid tumors correlate with histopathology. MATERIALS AND METHODS: Twenty-two patients (nine women and 13 men; mean age, 33 years) with pathologically proven periosteal chondroid lesions were retrospectively reviewed. The imaging modalities included conventional radiography (n = 17), CT (n = 10), and MR imaging (n = 14). The images were reviewed by two osteoradiologists, with agreement by consensus. Evaluation criteria included lesion location, mineralization, and size; periosteal reaction; and cortical response. Intramedullary extension, adjacent intramedullary edema, soft-tissue edema, and intrinsic characteristics were also evaluated on MR imaging. After the evaluation, a radiologic diagnosis of chondroma or chondrosarcoma was obtained. An experienced osteopathologist who was unaware of the patient's medical history and radiologic findings reviewed all histopathology. Agreement between the radiologic and the histopathologic diagnosis was tested using the kappa analysis. Imaging features were correlated with the pathologic findings, and a statistical analysis was performed. RESULTS: Using strict pathologic criteria, we diagnosed 11 chondromas and 11 chondrosarcomas (nine, grade I; two, grade II). Moderate agreement was reached between the radiologic and the pathologic diagnosis (kappa = 0.55). The size of periosteal chondrosarcomas (range, 3-14 cm; median, 4 cm) was considerably larger than the size of the chondromas (range, 1-6.5 cm; median, 2.5 cm; p < 0.05). Other imaging features did not significantly correlate with benign versus malignant disease at pathology (all p > 0.05). CONCLUSION: A variable overlap existed in the imaging appearances of benign and malignant periosteal chondroid lesions, with size being the most reliable indicator in distinguishing the two lesions. This and the fact that histologic differentiation of the entities can be difficult, suggests that surgical wide excision may be the most appropriate procedure in treating patients with lesions greater than 3 cm.

Tibial turn-up for long distal femoral bone loss.

Since 1990, seven patients have been treated by the authors with the tibial turn-up procedure. They have ranged in age from 8 to 37 years; four were skeletally mature adults and three were children. All seven patients were faced with a clinical situation that required surgical removal of a long portion of their affected distal femur. Three of the adult patients initially were treated for osteosarcoma with long distal femoral resections and allograft arthrodesis of the knee. The allografts ultimately failed, two because of aseptic failure and one because of infection. One patient required distal femoral removal for chronic osteomyelitis and pathologic fracture. Of the three children who were treated, two had turn-ups after long resection of the distal femur for bone malignancy, and one had a secondary turn-up after failure of a long distal femoral endoprosthesis. The technique uses the normal ipsilateral tibia as a vascularized pedicle graft to restore femoral length. The ultimate result, even after very high above knee resection, is a long above knee amputation stump. The followup of the patients in the current study ranged from 2 to 8 years. All patients achieved healing and were able to wear above knee prostheses. The tibial turn-up is an effective procedure that results in a long functional above knee amputation stump even after very high above knee resections.

Imaging findings in pseudocystic osteosarcoma.

OBJECTIVE: Our purpose was to describe four female patients with osteosarcoma whose clinical and imaging findings primarily suggested either simple or aneurysmal bone cyst. All lesions were osteolytic, intracompartmental, and expanded bone without periosteal reaction. None of the patients presented during the peak age incidence for osteosarcoma. From imaging to histologic diagnosis, the discovery of osteosarcoma ranged from 1 week to 3 years. CONCLUSION: Atypical osteosarcoma may rarely mimic simple or aneurysmal bone cyst radiologically and may show a nonmalignant rate of growth. It may be more frequently encountered in females and may not present during the peak age incidence for osteosarcoma. Microscopically, the tumors were not cystic, necrotic, or telangiectatic but were conventional osteosarcoma and osteoclast-rich osteosarcoma.

Unsuspected metastases presenting as solitary soft tissue lesions: a fourteen-year review.

OBJECTIVE: To describe a series of patients with no known primary malignancy who presented with a solitary unsuspected soft tissue metastasis masquerading as a soft tissue sarcoma, and secondarily to describe the imaging appearance of these lesions. DESIGN: Records of two academic hospitals with active orthopedic oncology services were reviewed for patients meeting the above criteria. Clinical charts were examined, and the imaging appearance of the soft tissue lesions retrospectively reviewed. PATIENTS: Of 1421 patients examined for soft tissue lesions, 11 were found who met the above criteria. RESULTS: Of the 11 patients whose initial presentation was a solitary soft tissue metastasis, eight were found to have a primary lung cancer, two were diagnosed with adenocarcinoma of unknown primary, and adenocarcinoma of the colon was discovered in the remaining patient. CONCLUSIONS: The clinical presentation of a solitary soft tissue metastasis without a known primary malignancy is a rare occurrence, with an incidence of approximately 0.8%. Lung cancer is the primary neoplasm in a high percentage of these cases.

Myxoma of the humerus: an exceptional site of origin.

Myxoma of bone, outside of the jaws, is exceptional. We present such a tumor in the humerus and discuss the criteria for the diagnosis of myxoma.

Primary leiomyosarcoma of bone.

OBJECTIVE: This study describes radiographic and MR imaging features of primary leiomyosarcoma of bone. SUBJECTS AND METHODS: Twelve patients (five men and seven women, 39-79 years old) who were treated at two oncology centers for primary leiomyosarcoma of bone involving the femurs, tibia, ilium, and inferior pubic ramus were studied. None of the patients had preexisting disease or disease elsewhere at the time of diagnosis. Pathologic diagnosis was obtained in all patients. RESULTS: Radiographs of all patients showed a matrix that was exclusively osteolytic. In long bones (seven patients), the tumor had an average length of 11 cm (range, 7-17 cm) and revealed an elongated configuration. In the pelvis (five patients), the average length of the tumor was 10 cm (range, 4-15 cm). MR imaging confirmed an intramedullary lesion in all patients, with extension into the soft tissues in eight patients and no identifiable soft-tissue mass in the remaining four patients. Four of the five pelvic tumors had a prominent soft-tissue mass, whereas only four of the seven long bone lesions revealed a soft-tissue mass that was, in all instances, small. The tumor was hypointense on T1-weighted images and showed heterogeneous signal intensity on T2-weighted conventional and fast spin-echo sequences. We saw low signal intensity (short T2) in eight patients and homogeneous hyperintense signal intensity in one patient. In the remaining three patients, T2-weighted spin-echo sequences obtained with fat saturation showed high signal intensity (long T2) in the tumors. CONCLUSION: Primary leiomyosarcoma of bone is a rare tumor that on radiography reveals no matrix and on MR imaging reveals areas of T2 shortening in relation to fat on conventional and fast spin-echo sequences.

Metachronous multiple aneurysmal bone cysts.

We report on a 9-year-old boy with metachronous aneurysmal bone cysts involving the tibia and pubis respectively. The patient has been clinically and radiographically followed for 3 years.

Appendicular metastatic prostate cancer simulating osteosarcoma, Paget's disease, and Paget's sarcoma.

Skeletal metastases from prostate cancer is common and usually do not pose a diagnostic dilemma. This study reviews radiographic appearances of prostatic metastases to the appendicular skeleton in four patients where the appearances simulated osteosarcoma, Paget's disease and Paget's sarcoma. Prostatic metastases to long bones can produce appearances considered characteristic of other lesions and suggest misleading alternative diagnoses.

Assessment of argyrophilic nucleolar organizer region quantification in benign and malignant bone tumors.

Quantification of argyrophilic nucleolar organizer regions has been proposed as a technique that may aid in diagnosing and predicting the biologic behavior of a variety of neoplasms. A 1-step silver staining technique was used to identify and quantify argyrophilic nuclear organizer regions in a series of 96 bone tumor specimens. Malignant bone tumors had a higher mean argyrophilic nuclear organizer region count (3.05 +/- 0.82) than giant cell tumors (1.39 +/- 0.14, p < 0.001) and benign bone tumors (1.51 +/- 0.42, p < 0.001). Despite these differences in mean counts, an overlap of argyrophilic nuclear organizer region scores was observed in some benign and malignant cases. The argyrophilic nuclear organizer region counts of the osteosarcomas were analyzed to determine whether they correlated with tumor behavior. The mean argyrophilic nuclear organizer region count of specimens from patients in whom metastatic disease developed was not significantly different than that of patients who remained disease free.

Limb-salvage surgery for treatment of sarcomas of the extremities.

The management of patients with sarcomas of the appendicular skeleton with limb-sparing surgery has become the standard of care. This is the result of advances in the understanding of the biology and staging of tumors, improvement in reconstructive techniques, and development of effective adjuvant chemotherapy and radiotherapy. A limb-sparing approach is applicable to virtually any bone lesion, whether low grade or high grade, and to all of the common primary soft-tissue sarcomas.

Periosteal Ewing sarcoma.

PURPOSE: To evaluate the imaging and histopathologic findings and clinical course of patients with periosteal Ewing sarcoma (PES). MATERIALS AND METHODS: Conventional radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) images in 10 adolescents and one adult were evaluated for the extent and character of PES. RESULTS: Ten of 11 masses were in the proximal extremities and one in the fibula; nine were diaphyseal and two, metadiaphyseal. Radiographs and CT scans showed a subperiosteal mass that did not invade the medullary cavity, was contiguous with and elevated the periosteum, and produced a Codman triangle and periosteal reaction. No PES exhibited osseous or cartilaginous matrix calcifications. MR imaging and histopathologic examination helped confirm the sparing of cancellous bone and the subperiosteal location. CONCLUSION: PES differs from the more common medullary and soft-tissue Ewing sarcomas in location, marked male predominance, and lack of presenting metastases. Except for the absence of matrix calcifications, PES resembles other periosteal sarcomas in imaging characteristics and a less aggressive clinical course.

Case report 799: Extraskeletal chondrosarcoma (Fig. 3).

In summary, extraskeletal chondrosarcoma is a rare soft tissue tumor. There may or may not be calcification, and in uncalcified tumors the diagnosis may not even be considered by the radiologist. The body of information as to clinical outcome is limited. Both of the patients whose tumors have been illustrated here are alive 2 years following surgery.

Giant cell tumor of the capitate. A case report.

Giant cell tumors in the small bones of the hand are unusual, particularly in the carpus. A 28-year-old woman developed a giant cell tumor in the capitate. After biopsy, she was treated with complete excision of the capitate with no reconstruction. Five years later she had excellent hand function and no tumor recurrence. A careful roentgenographic and pathologic examination will distinguish between aneurysmal bone cysts and giant cell reparative granulomas. Complete excision of the involved bone is recommended.

Recurrent hemarthrosis associated with gout.

Gout commonly occurs as an acute arthritis. In a 64-year-old man, gout was associated with a proliferative hemosiderin-laden synovitis. The association of recurrent atraumatic hemarthrosis seems not to have been reported in the literature on gout.

Prolongation of the QT interval by enflurane, isoflurane, and halothane in humans.

Previous investigations in laboratory animals have documented the ability of the volatile anesthetics to prolong the QT interval and the QT interval corrected for level of heart rate, QTc. The purpose of the present investigation was to evaluate the direct electrocardiographic and hemodynamic effects of enflurane, isoflurane, and halothane in healthy, unpremedicated patients using an inhalation induction to avoid the confounding effects of other anesthetic agents. Experiments were conducted in 22 adult male patients, (ASA physical status I or II) divided into three groups given either enflurane (n = 6), isoflurane (n = 8), or halothane (n = 8) anesthesia. Twenty-four-hour preoperative, preinduction, and postinduction hemodynamic and electrocardiographic measurements were obtained. Anesthetic blood concentrations, levels of plasma electrolytes, and arterial blood gas tensions were also quantitated. Halothane administration (0.81 +/- 0.06 mM) did not significantly alter the PR interval or QRS duration but significantly increased the QT (0.38 +/- 0.01 to 0.45 +/- 0.01 s) and QTc intervals (0.39 +/- 0.01 to 0.44 +/- 0.02 s). Isoflurane anesthesia (1.04 +/- 0.11 mM) did not significantly change QRS duration or PR and QT intervals but significantly prolonged the QTc interval (0.42 +/- 0.01 to 0.47 +/- 0.14 s). Similarly, enflurane anesthesia (2.16 +/- 0.13 mM) significantly prolonged the QTc (0.40 +/- 0.01 to 0.46 +/- 0.14 s) without change in QRS duration or PR and QT intervals. Plasma electrolyte levels and arterial gas tensions remained within normal limits in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance imaging in symptomatic Paget's disease.

Four patients with symptomatic Paget's disease of the appendicular skeleton were evaluated by magnetic resonance (MR) imaging. The plain film findings in each case were advanced but dissimilar. All patients had progressive symptoms of pain, and one presented with excruciating pain of short duration. The radiographic features included diffuse progressive osteolysis, cortical resorption, insufficiency fractures, bowing, and cortical and trabecular thickening. In three of the patients, MRI was performed to exclude sarcoma, revealing preservation of fatty marrow signal in all phases of Paget's disease except in patients with an acute fracture (demonstrated by MRI) and sarcoma. Small, focal, linear or oval areas of low signal seen against a background of normal marrow signal on short or long TR/TE do not mimic tumor. These findings suggest that fatty marrow signal is preserved in advanced Paget's disease unless an acute fracture or tumor is present.

Case report 651: Thrombosed, leaking popliteal aneurysm.

A thrombosed, leaking aneurysm of the popliteal artery, mimicking a soft tissue sarcoma both clinically and by MRI examination, is described. It may be difficult to separate a leaking, thrombosed aneurysm from an inflammatory response secondary to a sarcoma with intralesional hemorrhage. An aneurysm should, however, be considered in the differential diagnosis if the mass is present in a well-recognized location for aneurysm and is associated with vascular engulfment and signs of subacute or chronic hemorrhage.