An experimental model of ischemia in rabbit hindlimb.

This study was performed to establish an experimental model of ischemia for the investigation of new treatment modality of limb-threatening ischemia. We produced ischemia in the hindlimbs of 8 New Zealand white rabbits. Under general anesthesia, the left femoral artery was exposed, freed, and excised from distal external iliac artery to proximal popliteal and saphenous arteries. And then both hindlimbs were serially examined to assess the ischemia according to the time table until postoperative 6 weeks. We assessed clinical observation, blood pressure, radioisotopic perfusion scan, and angiography. Clinical ischemic changes of the operated feet were observed in 63%. The blood pressure of left calves was measurable on postoperative day 3 (p<0.05, vs preoperative day 2) and then gradually increased to reach a plateau in postoperative week 6. Radioisotopic arterial perfusion showed similar profiles as in blood pressure. Angiography of ischemic hindlimbs demonstrated a few collateral vessels arising from the internal iliac artery with the reconstitution of the posterior tibial artery in postoperative week 2. In postoperative week 6, collaterals remained the same in number. However, these became dilated and tortuous and showed reconstitution in distal hindleg. In conclusion, this is a reproducible, measurable, and economical animal model of hind limb ischemia.

Whole-body and pinhole bone scintigraphic manifestations of Reiter's syndrome: distribution patterns and early and characteristic signs.

The characteristic whole-body and pinhole scintigraphic manifestations of osteo-enthesopathy and arthropathy in Reiter's syndrome (RS) are described, with an emphasis on early diagnosis. We analysed 59 sets of whole-body and pinhole bone scintigrams of 59 patients with RS. The population comprised 47 men and 12 women with an age range from 15 to 53 years (mean=29.4). Bone scintigraphy was carried out 2-2.5 h after intravenous injection of technetium-99m hydroxydiphosphonate using a single-head gamma camera (Siemens Orbiter Model 6601) with a low-energy high-resolution and a 4-mm pinhole collimator for whole-body and pinhole scintigraphy, respectively. In total 262 lesions of osteo-enthesopathy and arthritis were detected on 59 whole-body scintigrams, an incidence of 4.4 lesions per patient. As anticipated, the lesional distribution was asymmetrical: 68% were in the lower limb skeleton and 32% in the axial and upper limb skeleton. Pinhole bone scintigraphy, applied selectively to one region of interest in each case, enabled us to accurately diagnose arthritis and osteo-enthesopathy. It was noteworthy that osteo-enthesopathy, alone or in combination with arthritis, occurred in 78.9%, and had a strong predilection for the foot bones, especially the calcaneus (25. 6%). Pinhole scintigraphy detected enthesopathy in the absence of radiographic alteration in 14.1% of cases and portrayed characteristic signs of RS in 6.9%. Whole-body bone scintigraphy augmented with pinhole scintigraphy was found to be useful in order to panoramically display the systemic involvement pattern, to assess the characteristic bone and articular alterations and to detect early signs of RS.

Dual-head pinhole bone scintigraphy.

UNLABELLED: This article describes dual-head pinhole bone scintigraphy (DHPBS), which makes use of two opposing pinhole-collimated detectors to obtain one pair of magnified images of bone and joint at one time. The aims are to reduce scan time and solve the problem of the blind zone that is created in the background in single-head pinhole bone scintigraphy. METHODS: DHPBS was used for normal hip and knee joints and one case each of lumbar spondylosis, vertebral compression fracture and pyoankle. The gamma camera used was a digital dual-head SPECT camera (Sopha Camera DST; Sopha Medical Vision International, Buc Cedex, France) connected to an XT data processor and a printer. Each of two opposing detectors was collimated with either a 3- or 5-mm pinhole collimator. The scan was performed 2-3 hr postinjection of 12-25 mCi 99mTc-oxidronate. Some 1500-2000 Kilocounts were accumulated at 15-40 min per pair. Anterior and posterior views were taken for the spine and hip and medial and lateral views for the knee and ankle. DHPBS images were correlated to radiographs. RESULTS: DHPBS produced a pair of high-resolution bone and joint images at one time, reducing scan time by nearly half for each image. The paired DHPBS images clearly visualized both foreground and background objects, which effectively eliminated the blind zone. CONCLUSION: DHPBS can significantly improve efficiency and diagnostic acumen.

Pinhole SPECT imaging in normal and morbid ankles.

UNLABELLED: Pinhole SPECT can generate sectional nuclear images of a normal and morbid ankle and hindfoot with remarkably enhanced resolution by portraying the topography and pathological alterations in great detail. METHODS: Pinhole SPECT was performed using a commercially available single-head, rotating gamma camera system by replacing the parallel-hole collimator used for planar SPECT with a pinhole collimator. The images were reconstructed in the same way as in planar SPECT by using the filtered back-projection algorithm and a Butterworth filter. First, we compared the scan resolution between the planar and pinhole SPECT images of a thyroid phantom and a normal ankle and hindfoot by working out pinhole SPECT anatomy with CT validation. Second, the clinical usefulness was assessed in one case each of fracture, reflex sympathetic dystrophy syndrome and rheumatoid arthritis of the ankle with radiographic correlation. The resolution of the pinhole SPECT and planar pinhole images was compared for these diseases. RESULTS: The resolution of the pinhole SPECT of a thyroid phantom and of a normal ankle and hindfoot was significantly enhanced compared to the planar SPECT although image distortion was seen in the periphery of the field-of-view. The pinhole SPECT resolution was such that most of the anatomical landmarks were sharply delineated in the ankle and hindfoot and some useful diagnostic signs in the diseased ankle were visible. CONCLUSION: Pinhole SPECT can be performed using a single-head gamma camera system and filtered back-projection algorithm. It generates sectional scan images of both normal and morbid ankle and hindfoot with enhanced resolution portraying many anatomical landmarks and pathological signs in useful detail.

Prestenotic bronchial radioaerosol deposition: a new ventilation scan sign of bronchial obstruction.

UNLABELLED: This study was performed to assess the diagnostic usefulness of aerosol ventilation scanning in bronchial obstruction and bronchial stenosis. METHODS: Seven patients of bronchial obstruction and one patient with stenosis were studied. In each patient, obstruction was confirmed by bronchography, bronchoscopy and/or CT scan. Ventilation scanning was performed using the 99mTc-phytate aerosol generated by a BARC jet nebulizer. Scan manifestations were assessed in correlation with those of plain chest radiography, bronchography, CT scan and/or bronchoscopy. RESULTS: In every patient, the ventilation scan showed characteristic intense aerosol deposition in a short, slightly dilated, clubbed, bronchial segment immediately proximal to obstruction or stenosis. Typically, it was accompanied by a distal airspace deposition defect. CONCLUSION: Intense, segmental, bronchial aerosol deposition with distal lung defect was a specific finding of bronchial obstruction and stenosis. The sign was especially useful when obstruction was obscured by the associated, bizarre lung disease and in a small bronchus.

Computer-aided design optimization with the use of a fast dose model for linear-accelerator-based stereotactic radiosurgery.

In order to efficiently plan non-spherical radiosurgical targets we have used computer-aided design optimization techniques with a fast dose model. A study of the spatial dose distribution for single or multiple non-coplanar arcs was carried out using a 18 cm diameter spherical head model. The dose distribution generated from the 3D dose computation algorithm can be represented by a simple analytic form. Two analytic dose models were developed to represent the dose for preset multiple non-coplanar arcs or a single arc: spherical and cylindrical. The spherical and cylindrical dose models compute dose quickly for each isocentre and single arc. Our approach then utilizes a computer-aided design optimization (CAD) with the use of two fast approximate dose models to determine the positions of isocentres and arcs. The implementation of CAD with fast dose models was demonstrated. While the fast dose models are only approximations of the true dose distribution, it is shown that this approximate model is sufficient to optimize isocentric position, collimator size and arc positions with CAD.

Bone pathologic correlation of multimodality imaging in Paget's disease.

The pagetic bones in the active phase of the disease with brisk lysis and sclerosis manifest intense tracer uptake on planar bone and SPECT images. Intense tracer uptake, however, can occur also in infections, dysplasias and metastases. Pinhole bone scintigraphy has been shown to portray specific diagnostic signs in a number of skeletal diseases. In an effort to identify useful bone scan signs, we prospectively carried out 99mTc-oxidronate pinhole bone scintigraphy of the skull, vertebrae, ribs, humerus, sacrum and ilium in two patients with Paget's disease of the bone. The pinhole bone scintigraphy findings correlated with radiographic, CT and MRI findings and in the vertebra with the pathological study. Interestingly enough, pinhole bone scintigraphy revealed intense tracer uptake preferentially in the bone cortex and the rim of the affected bones. Thus, the cranial inner table, humeral cortex and vertebral endplates and rims were the seats of characteristic tracer uptake, respectively creating a scintigraphic version of the radiographic "cotton wool" sign, "casket" sign and "picture frame" sign. The pagetic lesions in the sacrum and ilium also showed intense cortical and rim uptake. Correlation of pinhole bone scintigraphy with radiography, CT and MRI indicated that such cortical or rim uptake is characteristic of Paget's disease.

Radioprotective effect of captopril on the mouse jejunal mucosa.

PURPOSE: Captopril, an inhibitor of angiotensin I converting enzyme, has been shown to modify radiation damage and prevent radiation injury of normal tissue in rats and pigs. The present study was carried out to determine whether captopril would reduce radiation changes in the proximal small bowel in mice. METHODS AND MATERIALS: Mice were subjected to whole body irradiation with 9 Gy or 15 Gy. Captopril was administered in drinking water at a regimen of 62.5 mg/kg/day (captopril group I) and 125 mg/kg/day (captopril group II), continuously from 7 days before irradiation to the end of each designed experiment. The jejunal damage was evaluated microscopically by crypt count per circumference and by histologic damage grading. RESULTS: Crypt number in the sham-irradiated control was 133 +/- 6.8/circumference. In both captopril group I and II, crypt numbers and histologic scores were not significantly different from those in the normal group. The 9 Gy and 15 Gy radiation alone groups showed significantly lower crypt counts and histologic scores compared with the sham-irradiated control group (p < 0.05). The groups exposed to 9 Gy radiation plus captopril I and II showed significantly higher crypt counts and lower histologic damage scores on the third day, and lower histologic damage scores on the fifth day compared with the 9 Gy radiation alone group (p < 0.05). The 15 Gy radiation plus captopril I and II groups had significantly higher crypt counts and lower histologic damage scores on the third day than those of the 15 Gy radiation alone group (p < 0.05). All mice of the 15 Gy radiation group succumbed to intestinal radiation death. CONCLUSION: Our results suggest that captopril provides protection from acute radiation damage to the jejunal mucosa in mice.

1H magnetic resonance spectroscopy characterization of neuronal dysfunction in drug-naive, chronic schizophrenia.

RATIONALE AND OBJECTIVES: We investigated the proton metabolism of right prefrontal white matter in drug-naive, chronic schizophrenic patients (n = 23), compared with healthy normal control subjects (n = 10), by using localized, water-suppressed in vivo 1H magnetic resonance (MR) spectroscopy. METHODS: All 1H MR spectroscopy examinations were performed on a 1.5-T MR imaging/MR spectroscopy system by using a point-resolved spectroscopy pulse sequence for localized volumes of 2 x 2 x 2 cm3. Proton metabolite ratios relative to creatine (Cr) were obtained using a Marquart algorithm. RESULTS: Drug-naive, chronic schizophrenic patients demonstrated a decrease in the N-acetylaspartate (NAA):Cr and choline (Cho):Cr ratios and an increase of the complex of gamma-aminobutyric acid (GABA) and glutamate (Glu)-containing ratio [(GABA + Glu):Cr] as compared with normal control subjects. CONCLUSION: Results suggest that the reduction of NAA and Cho may indicate neuronal dysfunction and that the elevation of GABA and Glu may play a role in chronic schizophrenia. 1H MR spectroscopy may be a useful modality in research and in the clinical evaluation of chronic schizophrenic patients.

Pinhole skeletal scintigraphic manifestations of Tietze's disease.

Tietze's disease (TD) is a self-limited, non-specific, inflammatory condition of the upper costochondral junction (CCJ). Unlike in many other skeletal diseases, radiography plays a relatively minor role in TD because radiographic changes are frequently obscured by physiological costochondral calcifications. Bone scanning is a sensitive test for TD, but its specificity is low. The present study has been conducted to assess prospectively whether pinhole scintigraphy (PS) can enhance diagnostic specificity in TD. Both planar and PS bone images were obtained in seven ribs of five patients with TD. Scans alterations were analyzed and compared with the radiographic findings. Planar scans showed "hot" areas in the region of the CCJ in all seven ribs, these hot areas lacking textural patterns. However, the magnified PS images of the CCJ showed two characteristic uptake patterns: drumstick-like uptake in acute cases and C- or inverted C-shaped uptake in chronic cases. Radiographically, chondritic sclerosis could be seen when physiological chondral calcifications were minimal or absent, but was observed when the calcification was prominent. The correlation of PS and radiographic findings revealed that C- or inverted C-shaped uptake indeed faithfully reflected the inflammatory process in the CCJ, the medial border of which is concave. The further correlation of magnetic resonance and PS images of two lesions in one patient in whom histological examination was performed showed that C- or inverted C-shaped uptake is closely associated with hypervascularity of TD. Differential diagnosis between TD, fracture and metastasis is discussed.

Posterior lumbar apophyseal ring fractures: a report of 20 cases.

Posterior apophyseal ring fracture (PARF) of the lumbar spine is an uncommon injury thought usually to occur in adolescence. We analysed CT findings in 20 cases (19 patients), whose age ranged from 16 to 45 years (average 30 years). The PARF could be divided into two distinct groups on the basis of the shape and location of the fracture and the defect of the vertebral rim. In group 1 (2 cases), PARF involved the central aspect of the inferior vertebral rim and bone fragments were large and broad-based. In group 2, PARF were located at the posterolateral margin of the superior vertebral rim and bone fragments were small and focal. The great majority of previously reported cases belonged to our group 1. A pathogenesis for each group is suggested.

Pinhole scintigraphic sign of chondromalacia patellae in older subjects: a prospective assessment with differential diagnosis.

UNLABELLED: Chondromalacia patellae (CP) is an important cause of anterior knee pain. Two clinical types are known: one that typically affects young subjects and the one that affects older patients. The primary diagnostic approach is radiography reinforced with arthrography. A 99mTc-MDP bone scan is invaluable in the study of bone diseases especially when augmented with pinhole scintigraphy (PS). In this study previously unknown, specific sign of CP demonstrated by PS in six middle-aged and elderly patients is described. METHODS: Noting an increased patellar uptake in a planar spot view, a medial PS scan of the patella was taken to detail the uptake pattern using a 3-mm or 4-mm aperture pinhole collimator. The uptake pattern was analyzed in terms of location, definition, mode, grade and other associated changes, and correlated with radiographic and CT scan alterations. RESULTS: The planar views showed patellar uptake to be diffuse and nonlocalizing in five patients and ill-defined and spotty in the remaining patient. In contrast, PS revealed small, spotty uptake well localized in the central retropatellar facet in all but one patient in whom uptake was segmental. A control PS study of 16 patients with their patellas involved by osteoarthritis (n = 6), rheumatic arthritis (n = 5) and Reiter's syndrome (n = 5) also revealed retropatellar uptake with or without anterior patellar uptake in every patient. The CP with localized osteolysis or osteopenia accumulated tracer intensely, whereas those without showed mild to moderate uptake. CONCLUSION: Spotty tracer uptake occurring exclusively in the central retropatellar facet without other knee joint alteration appears pathognomonic of CP in older patients.

Intussusception: characteristic radiolucencies on the abdominal radiograph.

Six hundred and twenty-five sets of supine and erect abdominal radiographs of 288 patients with the confirmed diagnosis of intussusception (315 episodes) and 310 patients without intussusception were reviewed retrospectively to determine the characteristic radiographic features of intussusception. Among the patients with intussusception, 155 episodes (49%) showed a soft tissue mass and nearly half of these (71) showed characteristic radiolucencies (target, crescentic, or amorphous) in the soft tissue mass. Thirty-five episodes showed the radiolucencies on both the supine and erect radiographs; in 16 cases the type of radiolucency differed on the two films. In patients without intussusception, abnormal radiolucencies were seen in only seven cases (2.3%). Computed tomography performed prospectively in five patients showed the radiolucencies in the soft tissue mass to be intussuscepted mesenteric fat. We conclude that abnormal radiolucencies in the soft tissue mass on plain radiographs are characteristic of intussusception.

Optimisation of dose distribution for linear accelerator-based stereotactic radiosurgery.

The work presented in the paper addresses a method for obtaining the optimal dose distribution for LINAC-based stereotactic radiosurgery. As many targets have nonspherical or irregular shapes and three-dimensional dose calculations included in dose optimisation, long computation times are required to determine the optimum isocentre separation and collimator sizes to shape the irregular target using the multiple-isocentre approach, by trial-and-error types of method. The simple approach, using a computer-aided design optimisation technique and a fast approximate dose model, has been developed to find the optimum isocentre positions and collimator sizes quickly and automatically. A spherical dose model has been developed to represent the dose for a standard arc system with a single isocentre. The implementation of computer-aided design algorithms with the spherical dose model and their application to several cases are discussed. It is shown that the spherical dose model gives dose distribution similar to that of the exact dose model, which makes this simple dose model more efficient, with computer-aided design optimisation, in finding optimum isocentre positions and collimator sizes used in stereotactic radiosurgery.

Lung abscess. Percutaneous catheter therapy.

Lung abscess was successfully treated with percutaneous drainage in 5 of 6 patients. Complete abscess resolution occurred in 4 patients, partial resolution in one, and no response in one. The duration of drainage ranged from 7 to 18 days (mean 15.5 days) in successful cases. The failure of drainage in one neurologically impaired patient was attributed to persistent aspiration. In 2 patients, concurrent pleural empyema was also cured. CT provided the anatomic details necessary for choosing the puncture site and avoiding puncture of the lung parenchyma. Percutaneous catheter drainage is a safe and effective method for treating lung abscess.

CT analysis of intestinal obstruction due to adhesions: early detection of strangulation.

We evaluated the CT of intestinal obstruction due to adhesions in 20 postoperative patients, with emphasis on early detection of strangulation. Ten patients with surgically proven strangulated obstruction (strangulation group) were compared with another ten patients (nonstrangulation group) in whom seven improved with conservative management and three had confirmed simple obstruction on surgical exploration. Beak-like luminal narrowing ("beak") was the most common CT finding at the obstructed site in both groups. The CT findings that suggested strangulated obstruction were serrated beaks, mesenteric edema or vascular engorgement, and moderate to severe bowel wall thickening. In contrast, simple obstruction could be assumed when the beak was smooth, there were no mesenteric changes, and the bowel wall was normal or mildly thickened. Computed tomography is a useful tool for detecting strangulation in patients with postoperative adhesive intestinal obstruction.

Use of film duplicator to lighten dark radiographs.

The authors introduce a simple technique for lightening overexposed or overdeveloped dark radiographs. With the technique, an increase of exposure time in film duplicator allows production of duplicate radiographs with an appropriate tone. With this manipulation, image details are greatly improved, and the original radiograph is not damaged.

Pulmonary nocardiosis manifested as miliary nodules in a neonate--a case report.

A case of pulmonary nocardiosis in a 18-day-old neonate is presented. The chest roentgenograms demonstrated the widespread nodularities, mimicking miliary tuberculosis. Nocardiosis is rare in childhood but should be included in the differential diagnosis of the disseminated nodularities seen in the chest roentgenogram.