A comparison of intertendinous and classical approaches to popliteal nerve block using magnetic resonance imaging simulation.

UNLABELLED: The classical approach to sciatic nerve block in the popliteal fossa (popliteal block) often requires multiple attempts to localize the sciatic nerve. Recently, it has been suggested that an intertendinous approach to popliteal block may result in a more consistent localization of the sciatic nerve. In the current study, we compared anatomical landmarks for the intertendinous and classical approaches to popliteal block with respect to the accuracy in localizing the sciatic nerve using magnetic resonance imaging simulation. Two anesthesiologists experienced in popliteal block drew landmarks for the intertendinous and classical approaches on 10 volunteers; a 1.5 Tesla superconducting magnet was used to obtain simultaneous, 10-mm thick, fast-spin echo proton density transverse axial sequences of the lower extremities. Using these acquired images, the two approaches were simulated off-line using previously identified landmarks. The spatial relationships of the simulated needle paths to the nerves and vessels in the popliteal fossa, as well as other relevant structures, were measured and compared. Simulation of the intertendinous approach to popliteal block resulted in needle-to-sciatic nerve contact in 14 legs (70%) versus 5 legs (25%) when the classical approach was used (P < 0.05). We conclude that the intertendinous approach might result in a more consistent localization of the sciatic nerve and may decrease the risk of sciatic vessel puncture. IMPLICATIONS: A simulation of popliteal block using magnetic resonance imaging in volunteers suggests that using tendons of the hamstring muscles as the anatomical landmarks yields a more consistent localization of the sciatic nerve.

Expression of pituitary-tumour transforming gene in colorectal tumours.

BACKGROUND: Basic fibroblast growth factor promotes angiogenesis and mitogenesis in colon carcinomas. Pituitary-tumour transforming gene (PTTG1) causes in-vitro and in-vivo transformation, regulates secretion of basic fibroblast growth factor, and inhibits chromatid separation. Most normal tissues show little or no PTTG1 expression but cancer cells express the gene abundantly. We postulated that PTTG1 expression in colorectal tumours is related to tumour invasiveness. METHODS: PTTG1 gene and protein expression were assessed in 68 colorectal tumours and compared with invasive characteristics, such as lymph-node invasion, evidence of metastases, tumour vessel density, and expression of basic fibroblast growth factor. PTTG1 expression is given in terms of the fold-increase over that in normal-adjacent colorectal tissue. FINDINGS: PTTG1 was overexpressed in all of 48 colon carcinomas (median fold-increase 2.2 [IQR 1.8-3.3]) and in 19 of 20 colonic polyps (2.2 [1.6-3.1]) compared with normal colonic tissue. Invasion of surrounding lymph nodes was associated with higher PTTG1 expression than in carcinomas limited to the bowel wall (3.4 [2.1-5.9] vs 1.9 [1.7-2.4], p=0.007), and higher PTTG1 expression was seen in more vascular than in less vascular tumours (2.6 [1.9-5.1] vs 1.9 [1.8-2.5], p=0.04). INTERPRETATION: Increased tumour PTTG1 expression may be a marker of invasive colorectal carcinoma and could represent a new therapeutic target.

Early involvement of estrogen-induced pituitary tumor transforming gene and fibroblast growth factor expression in prolactinoma pathogenesis.

Pituitary tumors are commonly encountered, and result from clonal expansion of a single mutated cell. Hypothalamic hormones, local growth factors and circulating sex steroid hormones promote pituitary tumor growth and expansion into large invasive tumors. Estrogen acting directly through its receptor and by stimulation of fibroblast growth factor regulates prolactin synthesis and secretion. Fibroblast growth factor-2 (bFGF) modulates angiogenesis, tumor formation and progression in many tissues, including the anterior pituitary. A pituitary tumor-derived transforming gene (PTTG) has been isolated, which is tumorigenic in vivo, regulates bFGF secretion, and inhibits chromatid separation. The human PTTG family consists of at least three homologous genes, of which PTTG1 is located on chromosome 5q33 and is expressed at low levels in most normal human tissues but is highly expressed in malignant human cell lines and in pituitary tumors. We report here that pituitary pttg is regulated in vivo and in vitro by estrogen. Maximal induction of rat pituitary pttg mRNA in vivo occurred early in pituitary transformation (normal cell to hypertrophic/hyperplastic cell), coincident with bFGF and vascular endothelial growth factor induction and pituitary angiogenesis. We also demonstrate that pttg expression is induced by bFGF, and show concordant pttg and bFGF expression in experimental and human pituitary adenomas. As bFGF and estrogen both induce pttg, and pttg expression coincides with the early lactotrophic hyperplastic response, angiogenesis and prolactinoma development, we propose a previously unknown paracrine growth factor-mediated mechanism for pituitary tumor pathogenesis and potentially other estrogen-regulated tumors.

Estimation of tumor stage and lymph node status in patients with colorectal adenocarcinoma using probabilistic neural networks and logistic regression.

Staging colorectal adenocarcinoma on the basis of biopsy specimens could identify patients who might benefit from neoadjuvant therapy without undergoing resection first. In this study, we evaluated the ability of artificial neural networks with genetic algorithms and multivariate logistic regression to predict the stage of 99 patients with primary colorectal adenocarcinoma by analyzing age, tumor grade, and immunoreactivity to p53 and bcl-2 with use of endoscopically obtained biopsy specimens. We correlated results with regional lymph node status and tumor stage, identified in subsequent colectomy specimens. bcl-2 and p53 protein expression were demonstrated by immunohistochemical methods, using formalin-fixed, paraffin-embedded biopsy tissues. Tumor grade was evaluated in hematoxylinand eosin-stained sections. Patients were divided into training (n = 75) and testing cases (n = 24). Several probabilistic neural networks with genetic algorithm models were trained, using the four prognostic features as input neurons and regional lymph node status or stage as output neurons. Data were analyzed with univariate statistics and multivariate logistic regression. The cases were divided into training (n = 40) and testing (n = 59). The best two models classified correctly the lymph node status of 20 of 24 test patients (specificity, 80%; sensitivity, 85%; positive predictive value, 86%) and the tumor stage of 21 of 24 test patients (specificity, 82%; sensitivity, 92%; positive predictive value, 85%), respectively. Tumor grade and p53 protein were statistically significant (P < .05) by analysis of variance for lymph node status and tumor stage. Logistic regression models with these two independent variables correctly estimated the probability of lymph node metastases in 44 of 59 test cases and the tumor stage of 43 of 59 test cases, respectively. Results indicated the usefulness of probabilistic neural networks in the population studied, but the findings should be validated with large groups of patients.

Virtual microscopy and the Internet as telepathology consultation tools. A study of gastrointestinal biopsy specimens.

Telepathology (TP) is the practice of pathology at a distance using videomicroscopy and telecommunication tools. We explore the use of "virtual microscopy" techniques and the Internet as tools for TP gastrointestinal biopsy consultations. Thirty-five gastrointestinal biopsy specimens were photographed in Los Angeles by using a high-resolution digital camera, a light microscope, and a Pentium 166 microcomputer. Several (2-8) digital photomicrographs were collected at 40x or 100x optical magnification, using 2,700 x 3,400 pixel resolution. The photomicrographs illustrated all the tissue fragments present in 1 of the biopsy levels. They were saved in medium compression JPEG image format. These images can be magnified digitally up to 600% without visible degradation and scrolled at different magnifications on a video monitor, simulating examination under a light microscope. The images files (281 to 3,324 KB) were attached to e-mail messages containing patient information and sent through the Internet to Michigan for interpretation using a Power Macintosh 7100 system. The e-mail process was successful in 100% of instances; 2 files were corrupted owing to user error and had to be resent. Additional photos were requested in 1 case. In 33 of 35 cases, there was diagnostic concordance between the original and the TP diagnoses. The 2 discrepancies were due to diagnostic disagreement. This technology offers pathologists relatively inexpensive and effective tools for gastrointestinal TP consultations.

Tomography versus computed tomography for assessing step off in intraarticular distal radial fractures.

Computed tomography scans have supplanted conventional tomography for many applications and often are considered the imaging study of choice for assessing intraarticular distal radial fractures. Concern about cost containment in healthcare delivery prompts the question of whether the two studies provide comparable information and at what cost. Common intraarticular distal radial fractures were created in 12 lightly embalmed cadaveric specimens. The fractures were fixed with radiolucent Kirschner wires. Articular step off was measured with a caliper. Plain radiographs, computed tomography scans, and trispiral tomograms were obtained of each specimen. Maximal step off was measured blindly by two musculoskeletal radiologists and four hand surgeons. The radiographic measurements were compared with the actual step off and expressed as a positive or negative deviation from the actual value. There was no statistically significant difference between computed tomography scans and tomograms in predicting step off. In addition, the difference between actual and radiographic measurements was insignificant in tomogram readings and different in one of the computed tomography measurements. In the authors' institution, a tomogram costs $200, and a computed tomography scan costs $562. Trispiral tomography is more accurate and cost effective than computed tomography, and thus when available should be considered the imaging modality of choice for assessing articular step off in distal radius fractures.

Hepatocellular carcinoma with fibrolamellar pattern in a patient with autoimmune cholangitis.

A 75-year-old woman with a 15-year history of autoimmune cholangitis underwent orthotopic liver transplantation because of progressive liver decompensation. A clinically unsuspected hepatocellular carcinoma was found. A portion of the tumor showed fibrolamellar differentiation. Hepatocellular carcinoma, either with the usual pattern or with a fibrolamellar pattern, is rare in the setting of primary biliary cirrhosis, but has been seen in the setting of autoimmune hepatitis. Autoimmune cholangitis is a relatively recently recognized form of autoimmune liver disease whose association with hepatocellular carcinoma has yet to be determined.

Considering Mycobacterium haemophilum in the differential diagnosis for lytic bone lesions in AIDS patients who present with ulcerating skin lesions.

Mycobacterium haemophilum has recently been recognized as a newly emerging cause of osteomyelitis in immunocompromised patients. While still uncommon, its incidence has increased significantly with the growing AIDS epidemic. Like its relative M. tuberculosis and M. intracellulare, this organism is acid-fast positive; yet unlike its more well-known counterparts, M. haemophilum requires iron-supplemented culture media and low incubation temperatures (30-32 degrees C) for growth. We describe a case of M. haemophilum osteomyelities in the distal femur of a 36-year-old HIV-positive male, who also presented with multiple skin ulcerations. In an AIDS patient with a lytic bone lesion and concomitant skin eruptions, the diagnosis of M. haemophilum should be entertained so that special culture media can be used and appropriate treatment administered.

Evaluation of "neocollateral" ligament formation by magnetic resonance imaging after total excision of the proximal interphalangeal collateral ligaments.

The presence of palpable thickening and maintenance of stability within weeks of total excision of the proximal interphalangeal (PIP) joint collateral ligaments is an established, although somewhat mysterious, phenomenon. To further investigate this postoperative thickening, magnetic resonance imaging (MRI) scans were obtained on 10 joints in 9 patients who had undergone total ligament excision for posttraumatic stiff PIP joints 3 months to 14 years earlier. Although the ultrastructure of these newly formed structures is yet unknown, their palpable consistency, MRI contour, distribution, and signal intensity suggest the formation of a new soft tissue structure, albeit scar, which has all the attributes of a collateral ligament. This MRI of a "neocollateral ligament" would help explain the consistent observation of complete joint stability within weeks following total excision of both PIP joint collateral ligaments. All patients from the 14-year span sampled were found to have a similar, consistent, linear low signal density structure crossing the joint margins and essentially identical to that of a normal collateral ligament.

MR evaluation of rotator cuff pathology using T2-weighted fast spin-echo technique with and without fat suppression.

OBJECTIVE: This study was designed to compare MR imaging findings from T2-weighted fast spin-echo images with and without fat suppression and then to compare surgical results with those MR imaging interpretations in the evaluation of rotator cuff disease. SUBJECTS AND METHODS: T2-weighted fast spin-echo images--with and without fat suppression--of 177 shoulder MR imaging studies were reviewed separately in a retrospective, randomized, and blinded fashion. Both sets of images were read in conjunction with the corresponding proton density-weighted images. The diagnosis of normal tendon, tendinosis, degeneration, and partial- and full-thickness tears was made using established criteria. RESULTS: T2-weighted fast spin-echo techniques with and without fat suppression showed excellent agreement in the diagnosis of normal tendon (kappa=.90) amd full-thickness tears (kappa=.98), good agreement for partial tears (kappa=.70) and moderate agreement for the combined group of tendinosis and degeneration (kappa=.53). MR imaging and surgical correlation in 43 patients showed 86% specificity (95% confidence interval, 65-96%) for intact tendons, and 100% sensitivity (95% confidence interval, 82-100%) for full-thickness tears on T2-weighted fast spin-echo imaging--both without and with fat suppression. For partial tears, MR imaging showed a sensitivity of 92% (95% confidence interval, 65-99%) with fat suppression and 67% (95% confidence interval, 39-86%) without fat suppression. CONCLUSION: T2-weighted fast spin-echo imaging--with or without fat suppression--is a highly sensitive technique in the diagnosis of normal tendons and complete tears of the rotator cuff. Because of increased lesion conspicuity, fat suppression tends to perform better in the diagnosis of partial tears.

Degenerative changes of the trapeziometacarpal joint: radiologic assessment.

The trapeziometacarpal joint is particularly prone to osteoarthritis due to the great amount of stress applied with everyday activities with the hands. In this essay, radiologic assessment and staging of "basal joint" osteoarthritis, treatments based on radiologic staging and intraoperative findings, and surgical complications are described.

Abnormal geometry of the distal radioulnar joint: MR findings.

Previously developed criteria of normal distal radioulnar joint (DRUJ) axial geometry were applied to routine magnetic resonance (MR) images of 50 wrists. All wrists lacked clinically evident DRUJ instability. An attempt to apply the three geometric criteria to seven of the cases was not possible, since the prescribed landmarks were not visible. The remaining 43 cases were retrospectively divided into a symptomatic group (25 wrists), with clinical abnormalities referable to the ulnar side of the wrist, and an asymptomatic group (18 wrists), with no such abnormalities. Abnormal DRUJ geometry was found in 12 symptomatic and 2 asymptomatic wrists. This difference between the groups is significant (p = 0.02), suggesting that many symptomatic wrists exhibit different DRUJ geometry than is found in most asymptomatic wrists.

Foot drop in a long-distance runner. An unusual presentation of neurofibromatosis.

An athletic patient presented with a nontraumatic peroneal neuropathy that failed to resolve after a period of rest. A magnetic resonance image (MRI) showed a multilobulated mass in the course of the common peroneal nerve consistent with a plexiform neurofibroma. Surgical exploration revealed a mass, which coursed from the midthigh to the fibular neck, that was intimately involved with the fibers of the nerve bundle and had cystic degeneration with vesicles along its length. The authors recommend MRI as highly accurate in diagnosing unusual causes of peroneal neuropathy.

Femoral neck anteversion in ballerinas.

The elite ballet dancer has greater-than-average turnout, or external rotation, in the hip. Anatomic constraints, such as the angle of version of the femoral neck, or the femoral neck anteversion (FNA) angle, may limit the amount of external rotation or turnout in the hip. The purpose of this study was to determine whether dancers who have better-than-average turnout have lower-than-average FNA angles. Fourteen elite female dancers from three major American ballet companies were studied. The FNA angles were measured in 28 hips by magnetic resonance imaging techniques. The mean FNA angle in the dancers measured 11.9 degrees (range, 4 degrees-24 degrees), and was similar to the mean FNA angle in the general population (11.4 degrees). It was concluded that the average femoral neck anteversion angle in this select group of dancers is similar to that of the general population, although none of the dancers in this study had severe femoral neck anteversion.

Value of unenhanced spin-echo MR imaging in distinguishing between synovitis and effusion of the knee.

OBJECTIVE: We performed a study to determine if unenhanced spin-echo MR imaging can be used to differentiate effusion from synovitis of the knee joint. MATERIALS AND METHODS: Unenhanced spin-echo MR imaging examinations of 1051 consecutive patients referred for evaluation of internal derangement of the knees were reviewed. Twelve of 550 knees with significant joint effusion also had thickened or irregular synovium. Of these, the cause of synovitis was proved in 10 patients. In the other two, the cause was unknown. RESULTS: Thickened synovium was of intermediate signal intensity on T1-weighted MR images compared with the lower signal intensity of joint effusion. In eight cases, the thickened synovium had an intermediate signal intensity on T2-weighted images relative to the high signal of the joint effusion. MR images in the other four cases showed increased signal intensity indistinguishable from that of joint effusion. CONCLUSION: Our experience suggests that unenhanced spin-echo MR images can be used to distinguish synovitis from effusion in the knee joint.

MR imaging of the knee: clarification of its role.

In an attempt to further delineate the role of magnetic resonance (MR) imaging in evaluating knee pathology, a retrospective study of 60 patients who underwent MR scanning before arthroscopy was undertaken. For medial meniscus tears, the sensitivity of MR imaging was 97% whereas its specificity was 77%. For lateral meniscus tears, MR imaging was 90% sensitive and 87% specific. The positive predictive value of MR imaging was 85% for medial meniscus tears and only 79% for lateral meniscus tears. The negative predictive value was 95% for the medial meniscus and 94% for the lateral meniscus. MR imaging had an accuracy of 93% in assessing anterior cruciate ligament pathology also. These results begin to clarify the role of MR imaging in evaluating intraarticular knee pathology. Grade III signals represented tears at arthroscopy more than 90% of the time. False-positive results occurred more frequently than false negative results did. The high negative predictive value of MR imaging indicates that with a negative MR image, the orthopaedist can reliably conclude that no meniscal pathology is present. MR imaging is a useful diagnostic tool; however, it should be used selectively and in conjunction with the clinical examination in evaluating internal derangements of the knee.

MR imaging of displaced bucket-handle tear of the medial meniscus.

A bucket-handle tear of the meniscus is a vertical or oblique tear with longitudinal extension toward the anterior horn in which the inner fragment is frequently displaced toward the intercondylar notch with resultant mechanical locking of the knee joint. A precise MR diagnosis requires identification of the centrally displaced fragment because the peripheral nondisplaced component may have only a subtle truncated or foreshortened appearance that may escape detection. Eighteen consecutive cases of displaced bucket-handle tears of the medial meniscus diagnosed by MR had a characteristic low-signal band extending across the joint and projecting over the medial tibial eminence. The posterior portion was parallel and beneath the posterior cruciate ligament on both sagittal and coronal images. Arthroscopy confirmed the presence and location of the displaced fragment in all 18 cases. Awareness of this characteristic MR finding may increase the sensitivity of MR imaging in the diagnosis of bucket-handle tears of the medial meniscus.

Magnetic resonance evaluation of anterior cruciate ligament repair using the patellar tendon double bone block technique.

The magnetic resonance (MR) appearance of the anterior cruciate ligament reconstruction was determined in 20 clinically stable and 2 clinically unstable knees for a total of 22 examinations. All patients studied had undergone knee reconstruction using the patellar tendon as graft material. The reconstructed anterior cruciate ligament varies in appearance. It appeared as a thick, well-defined, low signal band on T1- and T2-weighted sagittal and coronal images in 14 of 22 examinations. The remaining 8 knees showed a graft having one or more thin and attenuated, low signal intensity bands in the sagittal and/or coronal plane. In 3 of these cases, the grafts appeared thicker in the coronal plane. All cases, including the two clinically unstable knees, showed no break in graft continuity. Arthroscopy confirmed an intact but lax graft in the clinically unstable knees.

MRI of postamputation neuromas.

Magnetic resonance imaging of 24 symptomatic lower limb amputations revealed that postamputation neuromas were easily diagnosed in above-the-knee amputees. Visualization of nerve trunks in below-the-knee amputees was difficult due to greater compactness of calf muscles. Neuromas on magnetic resonance imaging appeared ovoid or rounded and were usually heterogenous and isointense with muscle. Magnetic resonance imaging also showed additional causes of stump pain such as scar formation, fat in atrophied muscles, soft tissue abscesses, osteomyelitis, and hematomas.

Magnetic resonance imaging of para-articular and ectopic ganglia.

This study was undertaken to evaluate the efficacy of magnetic resonance imaging in (1) improving preoperative identification of soft tissue ganglia and in (2) enhancing management by defining their origins, attachments, and extensions. Magnetic resonance images of 17 ganglia were evaluated for intrinsic signal, internal structure, overall shape, and relationship to joints and tendon sheaths using a Philips 0.5 Tesla superconductive magnet with receiver dedicated surface coils. Magnetic resonance imaging proved particularly well suited to delineating soft tissue ganglia and characterizing several of their distinctive diagnostic features which are not optimally imaged by other modalities such as computed tomography and ultrasound.