Biomedical subjects

R M Patten

Publications and source records attributed to R M Patten.

At least 19 recordsLinked to original sources

PubMed2000

Frequency and importance of transverse process fractures in the lumbar vertebrae at helical abdominal CT in patients with trauma.

PURPOSE: To evaluate the frequency and importance of transverse process fractures of lumbar vertebrae identified at helical computed tomography (CT) in patients with blunt abdominal trauma. MATERIALS AND METHODS: Helical abdominal CT scans in 536 consecutive patients with a history of blunt abdominal trauma were prospectively evaluated for transverse process fractures of the lumbar spine. The number and level of fractures were categorized and correlated to the retrospective and initial interpretations of the radiographs obtained at original trauma examination. Number and type of associated abdominal injuries were recorded. RESULTS: CT scans showed transverse process fractures in 39 (7.3%) patients. Seventy-nine fractures were identified (single fractures in 12 patients, multiple fractures in 27). Fractures were right-sided in 13 patients, left-sided in 24, and bilateral in two. Transverse process fractures of the L3 vertebra were most common (n = 25). Fractures were not reported in 20 (61%) of 33 initial radiographic assessments. Even at retrospective review, only 30 (57%) of 53 fractures were correctly identified. Transverse process fractures were associated with abdominal injuries in 20 (51%) patients; this association was statistically significant (P <.001). CONCLUSION: Initial conventional radiography is relatively insensitive in the detection of transverse process fractures of the lumbar spine. There is a statistically significant association between transverse process fractures and abdominal injury.

Abdominal Injuries↗

PubMed2000

CT detection of hepatic and splenic injuries: usefulness of liver window settings.

OBJECTIVE: This study was designed to assess the usefulness of liver window settings when performing abdominal CT for the detection and characterization of hepatic and splenic injuries. SUBJECTS AND METHODS: We prospectively evaluated helical abdominal CT scans for hepatic and splenic injuries in 300 consecutive patients with blunt abdominal trauma over a 4-month period. There were 204 males and 96 females with a mean age of 34 years (age range, 1-87 years). For each patient, initial CT diagnosis of hepatic or splenic injury was made from images obtained with standard abdominal window settings. CT scans were then immediately reinterpreted using additional images obtained at narrow window width (liver windows). Changes in conspicuity and characterization of injury were recorded. All CT examinations were performed with helical 7-mm collimation at a pitch of 1.5 after oral ingestion of diluted barium and during bolus IV administration of 125 mL of ioversol at a rate of 2-3 mL/sec. RESULTS: We detected hepatic or splenic injuries in 34 patients (11.3%). There were 19 hepatic injuries and 18 splenic injuries. Three patients had injuries to both liver and spleen. Conspicuity of hepatic or splenic injuries was mildly increased (+1 H) on liver windows in 16 patients, whereas the injury was equally conspicuous on both liver window and standard window images in 19 cases. In no case did review of the liver windows result in a change in grade of injury or reveal an injury that was not seen on standard abdominal window images. The total increased cost for printing liver windows was $5748. CONCLUSION: Routine use of liver window settings for abdominal CT in trauma patients has little clinical usefulness and is not cost-effective.

Abdominal Injuries↗

PubMed1999

Gas in the sternoclavicular joints of patients with blunt chest trauma: significance and frequency of CT findings.

OBJECTIVE: In trauma patients, gas (vacuum phenomenon) in the sternoclavicular joints could represent sequelae of significant distraction forces and thus serve as a potential marker for severe intrathoracic injury. We evaluated the significance and frequency of the finding of gas in the sternoclavicular joints on chest CT of patients with blunt trauma. SUBJECTS AND METHODS: We prospectively studied all chest CT examinations performed at our institution over a 14-week period for the finding of gas in the sternoclavicular joints. Chest CT examinations (n = 267) were performed in 234 patients. We excluded data from follow-up CT examinations (n = 33), limiting our evaluation to the initial CT examination for each patient. Of the study population, 103 patients (83 men and 20 women) who ranged in age from 14 to 79 years (mean, 40 years) had sustained blunt chest trauma. For all trauma patients, we recorded the mechanism of injury and the associated thoracic injuries. RESULTS: CT revealed gas in the sternoclavicular joints in 47 patients (21%). Gas was unilateral in 27 patients and bilateral in 20 patients. Sternoclavicular joint gas was seen in 39 (38%) of the 103 trauma patients but was found in only eight (6%) of the 131 nontrauma patients (p < .0001). In the 39 trauma patients with sternoclavicular joint gas, associated thoracic injuries were seen in 17 patients (44%); either a sternal fracture or a retrosternal hematoma was seen in three patients. Radiographically evident thoracic injury was revealed in 20 (31%) of the 64 trauma patients who had no gas in the sternoclavicular joint; however, 10 of these 20 patients had either a sternal fracture or a mediastinal hematoma. CONCLUSION: Although gas in the sternoclavicular joints is more frequently seen in patients with blunt chest trauma than in patients undergoing chest CT for other indications, this finding does not indicate a greater risk of significant mediastinal or thoracic injury.

Adolescent↗

PubMed1997

MR imaging of rotator cuff tears in individuals with paraplegia.

OBJECTIVE: The purpose of this study was to use MR imaging to evaluate the prevalence and extent of rotator cuff tears in paraplegic patients, who are at increased risk for impingement caused by overuse. MATERIALS AND METHODS: Sixty-four MR examinations of the shoulder were evaluated for partial or full-thickness rotator cuff tears and for single or multiple rotator cuff tendon tears. Thirty-seven MR studies were from paraplegic subjects (26 symptomatic, 11 asymptomatic), and 27 MR studies were from able-bodied subjects (17 symptomatic, 10 asymptomatic). RESULTS: Among subjects who were symptomatic and paraplegic, 73% of shoulders imaged showed evidence of rotator cuff tear on MR images compared with 59% of shoulders in able-bodied symptomatic subjects. Of all subjects with paraplegia, 57% of shoulders imaged showed rotator cuff tears. Among all paraplegic subjects, prevalence and severity of tears correlated positively with age and duration of spinal cord injury. Tears that involved the posterior portion of the rotator cuff were revealed on MR images in 74% of the paraplegic subjects compared with 50% of the able-bodied subjects. CONCLUSION: MR imaging revealed a high percentage and degree of severity of rotator cuff tears in individuals with paraplegia and thus proved useful in evaluating shoulders in these patients.

Adult↗

PubMed1996

MR characterization of post-irradiation soft tissue edema.

OBJECTIVE: Radiation therapy is often used to treat bone und soft tissue neoplasms, and commonly results in soft tissue edema in the radiation field. However, the time course, distribution and degree of this edema have not been well characterized. Our study was carried out to better define these features of the edema seen following neutron and photon radiation therapy. DESIGN AND PATIENTS: Two hundred and twenty-six patients underwent radiation therapy as part of combined modality management for musculoskeletal sarcomas between 1985 and 1993. Of these, 15 had surgical resection of their neoplasm, had no clinical evidence of recurrent disease, and had adequate MR follow-up that allowed sequential assessment of soft tissue following irradiation. Ten patients received photons with an average dose of 52.8 Gy. Five patients received neutrons with an average dose of 17.3 nGy. Sequential MR follow-up was available in these patients for an average of 22.8 months following radiation therapy. On each of the serial MR imaging studies, subcutaneous fat, muscle, and the intramuscular septa/fascial planes were graded subjectively as to size and signal intensity. RESULTS: In general, soft tissue signal intensity in the radiation field initially increased over time, peaking at about 6 months for neutron-treated patients and at about 12-18 months for photon-treated patients. Signal intensity then decreased slowly over time. However, at the end of the follow-up period, signal intensity remained elevated for most patients in both groups. Signal intensity in a particular tissue was greater and tended to persist longer on STIR sequences than on T2-weighted sequences. Survival analysis of signal intensity demonstrated much longer edema survival times for neutron-treated patients than for photon-treated patients. Signal intensity increase in the intramuscular septa persisted for much longer than for fat or muscle. A mild increase in size was noted in the subcutaneous fat and intramuscular septa. Muscle, on the other hand, showed a decrease in size following treatment. This was mild for the photon-treated group and more marked for the neutron-treated group. CONCLUSIONS: There is a relatively wide variation in the duration and degree of post-irradiation edema in soft tissues. This edema seems to persist longer in the intramuscular septa than in fat or muscle. Although the duration of follow-up was limited, our study suggests that this edema resolves in roughly half the photon-treated patients within 2-3 years post-treatment and in less than 20% of neutron-treated patients by 3-4 years post-treatment. Muscle atrophy was seen in both photon- and neutron-treated patients, but was more severe in the neutron-treated group.

Adipose Tissue↗

PubMed1995

Overuse syndromes and injuries involving the elbow: MR imaging findings.

Most elbow injuries result not from acute trauma but from repetitive microtrauma and chronic stress overload of the joint. Such "overuse" injuries may be difficult to diagnose clinically. Occasionally, even acute traumatic injuries may be occult radiographically and difficult to detect. In patients with elbow pain of uncertain origin, MR imaging may improve diagnostic specificity and accuracy. In this essay, characteristic MR imaging findings in common traumatic and overuse syndromes of the elbow are illustrated.

Adolescent↗

PubMed1995

Association of sonographically detected subacromial/subdeltoid bursal effusion and intraarticular fluid with rotator cuff tear.

OBJECTIVE: Although an association between sonographically detected joint fluid and rotator cuff disease has been reported, the significance of sonographically detected subacromial/subdeltoid bursal effusion has not been studied. We examined a group of patients who had shoulder sonography and surgery to determine the association between bursal and joint effusion and surgically proved tears of the rotator cuff. MATERIALS AND METHODS: We retrospectively reviewed the preoperative shoulder sonography reports of 163 patients for the presence of fluid within the subacromial/subdeltoid bursa or glenohumeral joint. Surgical reports were obtained to determine the status of the rotator cuff. The sonographic reports of 232 asymptomatic shoulders were also reviewed to determine the prevalence of fluid within the subacromial/subdeltoid bursa or the glenohumeral joint. RESULTS: Sixty-seven (41%) of the 163 patients had a joint effusion, bursal fluid, or both. Joint effusion alone was seen in 35 patients. Fourteen of these had a normal rotator cuff at surgery, and 21 had a rotator cuff tear (sensitivity, 22%; specificity, 79%; positive predictive value, 60%). Bursal fluid alone was seen in 10 patients, seven of whom had a rotator cuff tear (sensitivity, 7%; specificity, 96%; positive predictive value, 70%). In 22 patients, fluid was seen in both the bursa and the joint; 21 had surgically proved rotator cuff tears (sensitivity, 22%; specificity, 99%; positive predictive value, 95%). Of the 232 asymptomatic shoulders, 16 (6.9%) had isolated joint effusions, eight (3.4%) had isolated bursal effusions, and four (1.7%) had both joint and bursal effusions. CONCLUSION: The sonographic finding of intraarticular fluid alone (without bursal fluid) has both a low sensitivity and a low specificity for the diagnosis of rotator cuff tears. However, the finding of fluid in the subacromial/subdeltoid bursa, especially when combined with a joint effusion, is highly specific and has a high positive predictive value for associated rotator cuff tears. Sonographically detected fluid in both the joint and the bursa is an uncommon finding in asymptomatic shoulders. The sonographic observation of fluid in the subacromial bursa, either isolated or combined with a joint effusion, should prompt a careful evaluation of the supraspinatus tendon for tear.

Acromion↗

PubMed1994

Diagnostic performance of magnetic resonance imaging for the diagnosis of rotator cuff tears using supplemental images in the oblique sagittal plane.

RATIONALE AND OBJECTIVES: The authors evaluated the diagnostic utility of supplemental imaging in the oblique sagittal (OS) plane for the magnetic resonance imaging (MRI) diagnosis of rotator cuff tears. METHODS: Two radiologists with varying levels of MRI experience blindly reviewed shoulder MR examinations of 50 patients for rotator cuff tears. Shoulder examinations were interpreted twice, initially using only double-echo spin-echo images obtained in the oblique coronal (OC) plane and later using double-echo spin-echo images obtained in the both the OC and OS planes. Tears were characterized according to size, location, and extent, and levels of diagnostic confidence were evaluated. RESULTS: Sensitivity and specificity of MR for the diagnosis of rotator cuff tear was 85% and 80%, respectively, with the OC series increasing to 95% and 93%, respectively with OCOS scans. However, these increases were not statistically significant. Receiver operating characteristic (ROC) curves suggest a trend toward increased diagnostic confidence when supplemental OS scans are available, especially for the less experienced reader. Characterization of rotator cuff tears was not improved with additional OS images. CONCLUSIONS: Supplemental OS scans did not demonstrate a definite improvement in diagnostic accuracy for rotator cuff tears compared to OC scans alone. Estimations based on sample size calculations indicate that a much larger population of patients would be needed to show a statistically significant difference.

Humans↗

PubMed1994

Age-related changes in marrow distribution in the shoulder: MR imaging findings.

PURPOSE: To define age-specific patterns of distribution of red and yellow marrow about the shoulder. MATERIALS AND METHODS: Red and yellow marrow distribution was reviewed on magnetic resonance images of 189 subjects aged 15-69 years. Double-echo and fast spin-echo, gradient, and short inversion time inversion recovery pulse sequences were used. The acromion, glenoid, and proximal humeral epiphysis, metaphysis, and diaphysis in each shoulder were graded semiquantitatively and qualitatively. RESULTS: There was a wide variation in the normal pattern of red-yellow marrow distribution both among subjects and among locations. All five anatomic locations showed an orderly progression from greater to lesser amounts of red marrow with increasing age. Many of the subjects had focal subchondral red marrow in the epiphysis, which was associated with patient age (P = .0001) and gender (P = .04). CONCLUSION: Knowledge of normal patterns of marrow distribution can prevent their being misinterpreted as marrow-based disease.

Acromion↗

PubMed1994

Tears of the anterior portion of the rotator cuff (the subscapularis tendon): MR imaging findings.

OBJECTIVE: Tears of the most anterior portion of the rotator cuff, the subscapularis tendon, are reported to be uncommon and rarely occur in isolation. The MR findings of subscapularis tendon tears have received little attention in radiologic publications. Accordingly, the objective of this study was to describe the MR imaging findings in the shoulders of patients with tears of the subscapularis tendon. MATERIALS AND METHODS: Preoperative MR images of nine patients with surgically confirmed rotator cuff tears that predominantly or exclusively involved the subscapularis tendon were analyzed. RESULTS: In all patients, MR imaging showed the contours of the subscapularis tendon to be poorly defined and the tendon itself to be of abnormally high signal intensity on T2- or T2*-weighted images. Discontinuity and frank retraction of the tendon were evident in seven patients (78%). Thickening of the distal portion of the tendon (n = 3) and calcification (n = 1) were seen less frequently. Associated abnormalities of the biceps tendon were common, seen in seven patients (78%), five of whom had medial dislocation of the tendon. Bone and labral injuries were uncommon. CONCLUSION: Tears of the subscapularis tendon can be identified on MR images as areas of disorganized tendon morphology and abnormal high signal intensity on T2- or T2*-weighted images. Abnormalities of the biceps tendon also are seen commonly. When subscapularis tears are recognized, the long head of the biceps tendon should be scrutinized for associated injury or malposition.

Humans↗

PubMed1994

Vacuum phenomenon: a potential pitfall in the interpretation of gradient-recalled-echo MR images of the shoulder.

OBJECTIVE: Axial gradient-recalled-echo (GRE) MR images of the shoulder obtained with the arm in external rotation may show a curvilinear or circular low-signal-intensity focus in the superior portion of the glenohumeral joint space that is thought to represent gas within the joint (vacuum phenomenon). This study was performed to determine the prevalence of this finding on GRE MR images of the shoulder to confirm that it represents gas in the joint, and to establish criteria to distinguish it from a true abnormality. SUBJECTS AND METHODS: We reviewed all external-rotation GRE images of 45 consecutive patients and 10 volunteers for the presence of low-signal-intensity foci and joint effusion. These findings were correlated with findings on corresponding spin-echo and GRE images of the shoulder with the arm in neutral position. MR findings also were correlated with findings on plain radiographs (37 patients) and shoulder CT scans (three patients and five volunteers) and with results of arthroscopy (19 patients). RESULTS: In nine (20%) of 44 patients and in five (50%) of 10 volunteers, axial external-rotation GRE images showed curvilinear or circular low-signal-intensity foci interposed between the opposing glenohumeral articular surfaces at the superior aspect of the glenohumeral joint that were not seen on MR images obtained with the arm in neutral position. In two of three patients and in all five volunteer subjects, CT scans of the shoulder showed a small focus of gas within the joint, corresponding in location to the intraarticular low-signal-intensity focus seen on MR images. Joint effusions were seen on MR images of 15 patients, and none of these images showed intraarticular gas. CONCLUSION: Circular or linear areas of low signal intensity are frequently seen on GRE MR images of the shoulder obtained with external rotation of the arm and represent small foci of intraarticular gas (vacuum phenomenon). Awareness of this potential pitfall and an understanding of the characteristic appearance and location of this collection of intraarticular gas may help prevent misdiagnosis of intraarticular loose bodies or chondrocalcinosis.

Adult↗

PubMed1993

Twin growth problems: causes and sonographic analysis.

Understanding the significant increased risks associated with twin pregnancies requires knowledge of the embryogenesis of twins and the unique placental characteristics seen only in twin gestations. Dizygotic "fraternal" twins, 70% of all twins, are at relatively low risk when compared with monozygotic twins, largely due to abnormalities seen in association with monochorionic placentation. The sonographic determination of chorionicity and amnionicity allows better estimation of pregnancy risk--up to 50% mortality in monochorionic-monoamniotic twins. Careful evaluation of intrauterine twin growth assists in the early identification of fetal abnormalities because normal twin growth should parallel that of singleton pregnancies until late in the third trimester. A number of the unique complications affecting growth in twin pregnancies are discussed, including twin transfusion syndrome, the "stuck twin" phenomenon, twin embolization syndrome, and development of acardiac twins.

Embryonic and Fetal Development↗

PubMed1993

Positive bowel contrast agent for MR imaging of the abdomen: phase II and III clinical trials.

PURPOSE: To evaluate the efficacy and safety of two dose levels of an orally administered ferric ammonium citrate-based contrast agent for bowel enhancement on T1-weighted spin-echo magnetic resonance (MR) images in 222 patients with known or suspected abnormality of the upper abdomen. MATERIALS AND METHODS: Adverse reactions were graded for intensity, frequency, duration, and relationship to the contrast agent. Twelve unblinded readers compared enhanced with unenhanced images; all MR images were evaluated by two independent offsite radiologists in a blinded review. RESULTS: No statistically significant changes in mean vital signs or laboratory values were seen. Forty-eight of 220 patients (22%) reported minor side effects. The readers found increased intraluminal signal intensity and improved contrast enhancement of the gastrointestinal tract and distention and improved signal homogeneity in 101-107 cases (89%-98%) after ingestion; the blinded reviewers' findings were similar. CONCLUSION: The contrast agent provided new or additional radiologic information in 142 patients (64%), specific additional information in a detected abnormality in 46 of 142 patients (32%), and information that changed diagnosis, management, or surgical approach in 22 of 142 patients (15%).

Abdomen↗

PubMed1993

Traumatic laceration of the liver limited to the bare area: CT findings in 25 patients.

OBJECTIVE: The capsular extent of traumatic hepatic lacerations may be limited to the bare area of the liver--an area not covered by peritoneal reflection. In these cases, intraperitoneal bleeding may not occur, classic peritoneal findings may be absent, and results of diagnostic peritoneal lavage may be normal. We undertook a study to evaluate the frequency, CT appearance, and significance of injury of the bare area of the liver. MATERIALS AND METHODS: We retrospectively reviewed radiologic reports of 1469 hemodynamically stable trauma patients referred for abdominal CT between January 1986 and September 1992 and selected 155 patients whose CT reports indicated hepatic injury. Retrospective review of the abdominal CT scans of these 155 patients confirmed intrahepatic laceration or contusion in all of them. The study involved the 25 (16%) patients in whom the capsular extent of injury was limited to the bare area of the liver. RESULTS: In all cases, CT scans showed simple or complex lacerations involving predominantly or exclusively the posterior segment of the right hepatic lobe, with capsular extent limited to the superomedial hepatic surface. Abnormal retroperitoneal findings were present in all but two cases. Twenty-two (88%) of 25 patients had right-sided retroperitoneal hemorrhage or fluid collections; adrenal hematoma or periadrenal fluid was seen in 12 (48%) patients. Abnormal pericaval fluid collections were present in nine (36%). Only five (20%) patients had free intraperitoneal fluid. Diagnostic peritoneal lavage, performed as a correlative procedure in four patients, revealed intraabdominal hemorrhage in one, equivocal findings in one, and normal findings in two. Patients who had isolated injuries of the bare area of the liver did well clinically and were discharged after an uneventful hospital stay of an average of 3 days (range, 2-7 days). CONCLUSION: A small percentage of hemodynamically stable patients who have hepatic trauma may have lacerations that primarily involve the bare area and that are not suspected clinically or detected by diagnostic peritoneal lavage. In these patients, CT may be helpful to show the extent of liver injury, identify associated retroperitoneal abnormalities, and provide prognostic information.

Abdominal Injuries↗

PubMed1993

CT of hypervascular hepatic tumors: are unenhanced scans necessary for diagnosis?

OBJECTIVE: In most institutions, a combination of unenhanced and contrast-enhanced CT is used to screen patients for suspected hypervascular hepatic neoplasms. Elimination of the unenhanced examination could save time and expense and reduce the patient's exposure to radiation. We compared unenhanced and incremental bolus dynamic contrast-enhanced CT for detection of hypervascular hepatic neoplasms and evaluated the need for preliminary unenhanced hepatic CT. SUBJECTS AND METHODS: We prospectively examined 101 consecutive patients with hypervascular primary hepatic malignant tumors or suspected hypervascular metastases. Primary hepatic neoplasms included hepatocellular carcinoma (seven), sarcoma (two), and hemangioendothelioma (one); extrahepatic primary tumors included breast (37) and renal cell (24) carcinoma, melanoma (15), carcinoid (nine), and endocrine and other tumors (six). All patients had both unenhanced and bolus dynamic contrast-enhanced CT with 5-mm collimated sections at 8-mm intervals. For contrast-enhanced CT, 150-180 ml of IV contrast material, a mechanical power injector, and a scanning protocol that allowed completion of liver imaging within 2 min were used. Both unenhanced and contrast-enhanced CT scans were compared for detection and conspicuousness of hepatic lesions. RESULTS: Hepatic lesions were found in 34 patients. In 21 patients, all hepatic lesions seen on unenhanced scans also were apparent on contrast-enhanced scans. However, in 12 (57%) of 21 patients, lesions were more conspicuous and better defined on contrast-enhanced scans. The absolute number of lesions detected with each method of scanning differed in 12 patients. In four patients, the contrast-enhanced scan showed more lesions; in five patients, the unenhanced scan showed more lesions; and in three patients, administration of contrast material obscured some lesions shown on unenhanced scans and made others more conspicuous. If only a contrast-enhanced CT scan had been obtained, the presence of malignant hepatic neoplasm would have been missed in only one case (a patient with a single 2.8-cm metastasis from renal cell carcinoma). CONCLUSION: Bolus dynamic contrast-enhanced CT alone correctly showed the presence or absence of primary or metastatic hypervascular hepatic tumors in 100 of 101 cases. If the goal of CT examination is detection of hypervascular hepatic lesions, use of contrast-enhanced CT alone may be adequate and the addition of unenhanced scans is not cost-effective.

Adult↗

PubMed1993

MR imaging with i.v. superparamagnetic iron oxide: efficacy in the detection of focal hepatic lesions.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of superparmagnetic iron oxide (SPIO) in the detection of focal hepatic lesions on MR images. SUBJECTS AND METHODS: The study included 21 patients with 115 focal hepatic lesions and eight patients without focal hepatic lesions. T1- and T2-weighted MR images were obtained at 1.5 T before and 60 min after the end of injection of an SPIO agent. Contrast-enhanced CT scans were obtained in all patients within 10 days after MR imaging. The effect of SPIO on the signal intensity of the liver and spleen was assessed by using quantitative analysis of the region of interest. Efficacy was evaluated by using multiple criteria and unenhanced and SPIO-enhanced images. Evaluations included subjective assessment of image quality, counting the number of lesions detected, and statistical analysis of quantitative changes in the signal intensity of lesions and of normal liver. RESULTS: By all criteria, SPIO-enhanced T2-weighted MR images were superior to unenhanced T2-weighted images and to contrast-enhanced CT scans. Conversely, by all criteria, SPIO-enhanced T1-weighted MR images were worse than unenhanced T1-weighted images and contrast-enhanced CT scans. The mean lesion-to-liver contrast on T2-weighted images was 317% on unenhanced images and 1745% on SPIO-enhanced images. For T1-weighted, the mean contrast was 26% on unenhanced images and 18% on SPIO-enhanced images. CONCLUSION: SPIO is an efficacious contrast agent for the detection of focal hepatic lesions when T2-weighted MR images are used.

Contrast Media↗

PubMed1992

Morphometry and histoenzymology of the hamster tenuissimus and its muscle spindles.

Muscle spindles and extrafusal fibers in the tenuissimus muscle of mature golden Syrian hamsters were studied morphologically and quantitatively using several light microscopic techniques. Muscle spindles were identified in serial-transverse frozen-sections of whole muscles stained with hematoxylin and eosin. Five tenuissimus muscles were examined from origin to insertion, and the locations of individual receptors were plotted in camera-lucida reconstructions. Spindles were found in proximity to the main neurovascular bundle in the central core of each muscle. A range of 16-20 receptors was noted per muscle. The mean muscle spindle index (the total number of spindles per gram of muscle weight) was 503 and the average spindle length was 7.5 mm. Oxidative enzyme and myosin adenosine-triphosphatase (ATPase) staining profiles were also evaluated in the intrafusal and extrafusal fibers in each muscle. Even numbers of type I and type IIA extrafusal fibers were distributed homogeneously throughout all muscle cross-sections. Histochemical staining patterns varied along the lengths of the three intrafusal fiber types. Nuclear chain fibers possessed staining properties similar to the type IIA extrafusal fibers and exhibited no regional variations. Bag1 fibers displayed staining variability, particularly when treated for myosin ATPase under acid preincubation conditions. Some spindles were isolated under darkfield illumination and then either treated with 7-nitrobenz-2-oxa-1,3-diazole (NBD)-phallacidin to detect filamentous actin by fluorescence microscopy, or prepared for conventional scanning electron microscopy (SEM). By fluorescence microscopy, a registered actin banding-pattern was observed in the sarcomeres of the intrafusal fibers, and variations in the intensity of banding were noted amongst different fibers. SEM revealed punctate sensory nerve endings that adhered intimately to the surfaces of underlying intrafusal fibers in the equatorial and juxtaequatorial regions. By transmission electron microscopy (TEM) these endings appeared crescent-shaped and were enveloped by external laminae. Each profile contained numerous mitochondria and cytoskeletal organelles. The high spindle density observed in this muscle suggests that the hamster tenuissimus may function in hindlimb proprioception.

Animals↗

PubMed1992

Patterns of intrahepatic bile duct dilatation at CT: correlation with obstructive disease processes.

The authors performed a blinded, retrospective analysis of 100 computed tomographic (CT) scans of patients with proved extrahepatic bile duct obstruction, including primary sclerosing cholangitis (PSC), to determine whether certain patterns of intrahepatic bile duct dilatation are suggestive of specific disease processes. Among 30 patients with benign obstructive disease, CT showed pruning of the intrahepatic ducts in four patients (13%), beading in four (13%), and skip dilatations in one (3%). Among 54 patients with malignant obstructive disease, CT illustrated pruning in eight (15%) patients, beading in 11 (20%), and skip dilatations in two (4%). Among 16 patients with PSC, CT demonstrated pruning in four (25%), beading in two (13%), and skip dilatations in five (31%). The majority of patients with malignant or benign obstructive disease or PSC had intrahepatic duct dilatation in both lobes of the liver. It extended into the periphery in 46 of 54 patients (85%) with malignant obstructive disease, in 20 of 30 (67%) with benign obstructive disease, and in 10 of 16 (63%) with PSC. The CT finding of skip dilatations is strongly suggestive of PSC. The CT findings of pruning and beading are nonspecific and may be observed at CT in patients with bile duct obstruction due to a wide variety of causes. The distribution and extent of intrahepatic duct dilatation at CT do not differ among biliary disease processes.

Bile Duct Neoplasms↗