Safe placement of proximal tibial transfixation wires with respect to intracapsular penetration.

OBJECTIVES: To determine the safe zone for transfixation wires in the proximal tibia to avoid intracapsular penetration. METHODS: The material consisted of five fresh cadaver knees (two paired) and seven knees of volunteer subjects (three paired). High-resolution magnetic resonance imaging (MRI) was performed on each knee after distension with a gadolinium solution. The distance d from the subchondral bone to the insertion of the reflected joint capsule was measured. Selected cadaver knees were then anatomically sectioned to correlate the MRI findings with anatomic measurements. RESULTS: On the anteromedial side of the knee, the distance from the reflected joint capsule to the subchondral bone was less than eleven millimeters in all specimens except one. Posteromedially, d was smaller and ranged from two to four millimeters. On the lateral side of the knee anterior to the proximal tibiofibular joint, this distance ranged from six to nine millimeters. In all knees but two, d was greatest at the posterior aspect of the proximal tibiofibular joint, ranging from eight to thirteen millimeters. In one volunteer knee, the septum that separates the knee joint from the proximal tibiofibular joint was either torn or attenuated, resulting in complete communication between these two synovial cavities. CONCLUSIONS: Proximal tibial transfixation wires away from the tibiofibular joint are likely to be extraarticular if kept greater than fourteen millimeters from the subchondral bone. In the region of the proximal tibiofibular joint, a safe distance is unclear because it is difficult to know preoperatively which knee has a torn septum.

Utility of low mA 1.5 pitch helical versus conventional high mA abdominal CT.

The objective of this study was to evaluate the utility of a low mA 1.5 pitch helical versus conventional high mA conventional technique in abdominal computed tomography (CT). Twenty-five patients who had both a conventional high mA (> 300) and a 1.5 pitch low mA (80-125) helical CT within 3 months were selected for inclusion in the study. Patients were excluded who had a significant change in pathology between the two studies. The other parameters (injection rate, contrast type and volume, and filming window/level) were constant. The studies were randomized and blinded to five separate experienced readers who graded the studies by a variety of normal anatomical structures and pathological criteria. Overview questions also assessed noise, resolution, contrast, and overall quality. The abdominal wall/retroperitoneum and hiatal hernias were statistically better visualized on the conventional high mA studies. However, for all other normal anatomical and pathological sites, there was equivalent or better visualization on the helical versus the conventional CT examinations. The resolution of the helical studies was graded statistically better than the high mA conventional CT scans as was the amount of noise present on the images. While there was some advantage for conventional high mA CT with respect to contrast enhancement and low contrast sensitivity, these differences were not statistically significant. It appears from the data of this study that a low mA technique in evaluating the abdomen may be a useful option in performing routine abdominal CT. The radiation dose savings to the patient is significant and there appears to be little degradation of image quality using a low mA 1.5 helical versus mA conventional CT technique.

Spatial variation of T2 in human articular cartilage.

PURPOSE: To determine the spatial variation of in vivo cartilage T2 in young asymptomatic adults. MATERIALS AND METHODS: Quantitative T2 maps of seven asymptomatic young male adults and one male volunteer with a history of previous intraarticular chondroid fragments were calculated by using a multiecho, spin-echo magnetic resonance imaging sequence at 3.0 T. The T2 maps were bilinearly interpolated to generate T2 profiles across the thickness of cartilage. RESULTS: All seven asymptomatic volunteers demonstrated a monotonic increase in T2, which increased from 32 msec +/- 1 in the deep radial zone and 48 msec +/- 1 in the deep transitional zone to 67 msec +/- 2 in the outer transitional superficial zone. The T2 profile of the volunteer with superficial fibrillation observed at arthroscopy demonstrated marked spatial heterogeneity and a statistically significant increase in cartilage T2. CONCLUSION: There is a reproducible pattern of increasing T2 that is proportional to the known spatial variation in cartilage water and is inversely proportional to the distribution of proteoglycans. The authors postulate that these regional T2 differences are secondary to the restricted mobility of cartilage water within an anisotropic solid matrix.

Current concepts and controversies in imaging of renal cystic diseases.

Renal cystic disease compromises a diverse group of inherited and acquired entities. This article reviews the clinical, pathologic, and radiologic findings of eight renal cystic diseases. For each entity, the current concepts of pathogenesis and pathophysiology are discussed. When appropriate, controversies concerning terminology, management, and malignant potentials are addressed. Renal cystic diseases that are discussed include autosomal dominant and autosomal recessive polycystic kidney disease, medullary sponge kidney, medullary cystic disease, multicystic, dysplastic kidney, von Hippel-Lindau disease, acquired cystic kidney disease, and tuberous sclerosis.

Renal cystic diseases.

Renal cystic disease comprises a mixed group of heritable, developmental, and acquired disorders. Because of their diverse etiology, histology, and clinical presentation, no single scheme of classification has gained acceptance. Conditions include autosomal dominant polycystic kidney disease, acquired renal cystic disease, medullary sponge kidney, autosomal recessive polycystic kidney disease, multicystic dysplastic kidney, medullary cystic disease, tuberous sclerosis, cysts of the renal sinus, and von Hippel-Lindau's disease. An awareness of the pathology of each cystic disease is helpful in the understanding of the corresponding radiological images. Imaging techniques used in evaluating renal cystic disease include intravenous urography, sonography, CT, MRI, nuclear medicine, and renal angiography. Many types of cystic disease show similar imaging features. Meticulous attention to subtle radiological findings is therefore essential for reaching a correct diagnosis. Imaging features requiring analysis include whether the cysts are unilateral or bilateral, renal size and functional status, cyst distribution in the kidneys, and the presence of hemorrhagic and calcified renal cysts, solid renal masses, renal sinus cysts, and cysts in adjacent organs. Radiological findings should be carefully correlated with clinical features such as patient age, family history, symptoms, physical findings, and renal functional status before a diagnosis is attempted.

The impact of 2D versus 3D quantitation of tumor bulk determination on current methods of assessing response to treatment.

PURPOSE: Measurements from sequential axial "2D" data in cancer patients are commonly used to assess treatment response or disease progression. This study compares the volume of tumor bulk calculated with 3D reconstructions with that calculated by conventional methods to determine if it might change patient classification. METHOD: All medical, gynecologic, and pediatric oncology patients under treatment who were evaluated with serial CT scans between January 1, 1992, and July 31, 1994, for whom the digital data were available were included in this study. For each tumor site, the maximum diameter and its perpendicular were measured and multiplied together to yield an area. The sum of areas of the measured lesions was used as an approximation of overall 2D tumor volume. In addition, the 2D area of each site was multiplied by its height, yielding a 2D volume. Last, the digital data were loaded into a 3D computer system and total 3D tumor volumes determined. All medical and gynecologic oncology patients were treated based upon the 2D area of tumor. The pediatric oncology patients were treated based upon the 2D volume of tumor measured as per standard practice. The members of each treating oncologic service assessed their patients as to how the other two methods would have changed their classification of the patients' response category. RESULTS: Four hundred thirty-three CT scans were performed in 139 patients, which included 204 baseline and 294 follow-up CT examinations. Seventy patients had new tumor foci and would have been classified as failure by all three methods of tumor bulk measurement. The 3D volume versus the 2D area method of tumor bulk assessment would have changed response categories in 52 of the 294 follow-up CT examinations (p < 0.0001). Thirty-five patients were recategorized from either "no response" to "failure" (21 patients) or "no response" to "response" (14 patients) categories. If only those follow-up studies without new metastatic foci are considered, the 3D volume versus the 2D area methods of tumor assessment would have changed the treatment response category in 23.2%. The use of the 2D volume method of calculating tumor volume of bulk tended to overestimate the overall tumor size by an average of 244 cm3 (p = 0.001). CONCLUSION: The 3D method of tumor volume measurement differs significantly from conventional 2D methods of tumor volume determination. Large prospective studies analyzing the usefulness of 3D tumor volume measurements and assessing possible changes in patient response categories would be required for full utilization of this more accurate method of following disease bulk.

Analysis of interobserver and intraobserver variability in CT tumor measurements.

OBJECTIVE: The purpose of this study was to evaluate the variability between radiologists interpreting thoracic and abdominal/pelvic CT scans in selecting specific sites of metastatic tumor for measurement (indicator lesions) and to assess interobserver and intraobserver variability in tumor measurement. MATERIALS AND METHODS: Three separate experienced radiologists were asked to review 24 combined thoracic and abdominal CT scans in patients with metastatic tumor. Each radiologist was asked to identify the indicator lesions representative of each patient's tumor bulk. In the second phase of the study, 105 specific foci on 26 combined thoracic and abdominal CT studies (including the original 24) were reviewed twice by the same three radiologists. Up to eight foci were randomly identified per patient, and each observer was asked to determine the slice with the maximum diameter for each tumor focus and to measure it in three dimensions (maximum diameter, its perpendicular, and length). RESULTS: A total of 132 tumor sites were present on the CT studies in phase I, all of which were chosen by at least one observer as an indicator lesion. Of the 116 of these that were separate and nonoverlapped, 57 (49%) were measured by only one observer, whereas 32 (28%) and 27 (23%) were measured by two or all three observers, respectively. Observers were more inclined to pick round or defined/well-defined lesions rather than irregular, oval, or poorly defined ones, although this tendency was not statistically significant. The second phase of the study showed considerable interobserver variability (15%) in CT tumor measurement, which was worse for poorly defined and irregular lesions. Intraobserver variability in measuring individual foci was less (6%). CONCLUSION: Radiologists interpreting thoracic and/or abdominal/pelvic CT scans for metastatic cancer should measure and report a significant number of each patient's tumor sites, especially larger ones in different anatomic areas. When interpreting a follow-up CT scan of a patient with metastatic cancer, the interpreting radiologist should remeasure the indicator lesions on the previous and on the follow-up CT scans, especially when the results will change the patient's treatment response category.

The quality of 3D reconstructions from 1.0 and 1.5 pitch helical and conventional CT.

PURPOSE: CT data are commonly used to create 3D images. For this purpose, thin and overlapped slices are desirable. Helical (spiral) CT offers the ability to adjust the slice reconstruction interval from 0 to 100%. However, its use in 1.0 and 1.5 pitch helical CT and 3D imaging, especially with respect to surface detail, is relatively untested. METHODS: Ten objects selected for their varying size, shape, and density were scanned (fourth generation Picker PQ2000) by contiguous 2,4 and 8 mm conventional and helical sequences. The latter were obtained with a pitch of both 1.0 and 1.5 and were reconstructed into a 3D image with 0-75% overlapping of the reconstructed slices. Each of the 24 different sequences per scanned object was reconstructed into identical sets (projections) of 3D images displayed on color film. The 24 3D image sets for each object were submitted to six blinded radiologists who separately ranked them from best to worst. RESULTS: 3D reconstructions obtained from CT scans with a thinner slice thickness, half-field (15 cm FOV), and helical technique were rated as statistically superior. The 1.0 and 1.5 helical sequences obtained with a 4 or 8 mm slice thickness scored statistically better than 3D reconstructions from equivalent conventional scans. Overlapping of the reconstructed helical slices by 25-75% generally improved the quality of the 3D reconstruction. CONCLUSION: Helical CT with either a 1.0 or a 1.5 pitch offers the ability to obtain higher quality 3D reconstructions than from comparable conventional CT scans.

MR imaging of periarticular soft-tissue lesions.

The exquisite soft-tissue contrast and multi-planar imaging capabilities of MR imaging uniquely qualify this modality for the evaluation of periarticular pathology. MR evaluation can be diagnostic by signal characterization, as in a lipoma, or by anatomic location, as seen in meniscal and synovial cysts. In other less diagnostic pathology, MR imaging can focus a differential diagnosis, guide percutaneous or surgical biopsy, provide local staging, and serve as a surgical map.

A reappraisal of the radiologic findings of acute inflammation of the epiglottis and supraglottic structures in adults.

PURPOSE: To evaluate the radiologic characteristic of acute inflammation of the epiglottis and supraglottic structures in adults. METHODS: The clinical and radiographic findings in 27 adult patients with epiglottitis (average age, 43 years; range, 28 to 81 years) were compared with those of a control group of asymptomatic subjects (n = 15; average age, 48 years; range, 24 to 79 years). Unusual clinical aspects in the current series included two patients who were positive for human immunodeficiency virus, 1 with acquired immunodeficiency syndrome and Kaposi sarcoma, 3 with emphysematous epiglottitis, 1 with abscess formation, and 1 with laryngeal carcinoma. One patient required emergency tracheostomy. One patient died of pneumonia. RESULTS: The ratio of the soft-tissue parameters to the anteroposterior width of the C-4 vertebral body yielded three key parameters of high statistical significance in adult epiglottitis. The ratio of the width of the epiglottis to the anteroposterior width of C-4 should not be greater than 0.33 (sensitivity, 96%; specificity, 100%). The ratio of the prevertebral soft tissue to C-4 should not exceed 0.5 (sensitivity, 37%; specificity, 100%) and the ratio of the width of the hypopharyngeal airway to the width of C-4 should be less than 1.5 (sensitivity, 44%; specificity, 87%). The aryepiglottic folds were enlarged in 85%, and the arytenoids were swollen in 70% of the patient population (specificity, 100%). CONCLUSION: These defined radiologic parameters should aid in the diagnosis of acute epiglottitis in adults.

MRI evaluation of diabetic muscle infarction.

Diabetic muscle infarction (DMI) is a painful and potentially serious complication in patients with poorly controlled diabetes mellitus. The incidence of DMI is likely much greater than reports in the literature suggest, perhaps secondary to the difficulty in making the diagnosis and excluding other more serious etiologies. This paper describes the role of MRI in the evaluation of a diabetic patient with a painful, swollen limb. Early application of MRI can more accurately classify the disease process and focus the differential diagnosis, thus avoiding the hazards of medical therapy associated with other etiologies such as deep venous thrombosis, cellulitis, or osteomyelitis. This paper describes the evaluation and diagnostic pitfalls encountered in two patients. MRI techniques and applications are presented with a discussion of clinical and radiological differential diagnoses.

Diabetic muscle infarction: an underappreciated cause of a painful swollen extremity. Evaluation with magnetic resonance imaging.

Diabetic muscle infarction (DMI) is a rarely reported complication of diabetes mellitus and usually occurs in patients with poorly controlled diabetes and/or significant end-organ complications. It is not unusual for these patients to undergo extensive work-up and treatment for thrombophlebitis, myositis, or vasculitis when DMI is not initially considered. We report the use of magnetic resonance imaging (MRI) to diagnose DMI on three occasions in two patients. We believe MRI should be considered early in the evaluation of diabetic patients with unexplained localized complaints in an extremity. In compatible clinical situations, MRI may lead to a swift diagnosis of DMI while excluding conditions requiring specific therapy. In addition, when the presentation is atypical, MRI may help focus further evaluation, i.e., localize which muscle to biopsy.

Failure of normal osteoclasts to resorb calcified cartilage from osteosclerotic (oc/oc) mice in vitro.

Osteosclerosis is an osteopetrotic mutation in the mouse characterized by reduced bone resorption, numerous small osteoclasts lacking elaborate ruffled borders, and resistance to cure by bone marrow transplants from normal littermates. The failure of osteosclerotic mice to be cured by bone marrow transplants could be due to the production of bone that is not resorbable by normal osteoclasts. We tested this hypothesis using a modification of the metatarsal organ culture system of Burger et al. (1982), in which metatarsals are cultured with various tissues that act as sources of osteoclast precursors. Metatarsals from neonatal mutants were isolated, and live bone rudiments were cultured with small cubes of liver or spleen from normal littermates for 7 days. Controls included normal and mutant metatarsals cultured alone or with spleen or liver from littermates of the same or different genotype. Mutant metatarsals cultured alone or with mutant tissue had small osteoclasts, no marrow spaces, and no evidence of bone resorption. Mutant metatarsals cultured with normal liver or spleen had larger osteoclasts, evidence of resorption of bone but not cartilage, and no marrow spaces because the calcified cartilage cores of metaphyseal trabeculae persisted. Normal metatarsals cultured with normal liver had large osteoclasts, bone resorption, and marrow spaces. By transmission EM, mutant trabeculae contained a layer of amorphous material between the central core of calcified cartilage and the surrounding bone matrix. This material was not present in normal metatarsals.(ABSTRACT TRUNCATED AT 250 WORDS)