TI-201 scintigraphy in muscle trauma.

Muscle uptake of Tl-201 thallous chloride in the larger or more major groups, particularly the legs, chest, and upper limb areas, is not uncommonly observed in healthy persons. However, as illustrated in three patients, such uptake, when localized or asymmetric, may provide evidence of unrecognized traumatized muscle, resulting from more chronic or subacute muscle overuse than the acute muscle insult that produces the marked uptake of Tc-99m phosphates associated with frank rhabdomyolysis.

Scintigraphic patterns of injury in amateur weight lifters.

PURPOSE: Weight lifting is now a standard part of training in most sports. An increasing number of amateur athletes are doing strength training, mostly in unsupervised situations. A series of injuries in amateur weight lifters was analyzed by bone scintigraphy, with the aim of depicting specific patterns that would accurately identify the primary lesions. METHODS: Twelve patients (10 men and 2 women) were studied whose ages ranged from 18 to 35 years. Patients were referred for bone scintigraphy with clinical diagnoses based on history, physical examination, and appropriate radiologic investigations. Diagnoses were confirmed by surgery, arthroscopy, arthrography, local steroid injection, and outcome. RESULTS: Most of the injuries were in athletes undertaking free-weight training. Most injuries were in the upper limbs, particularly around the shoulder. Scintigraphic patterns of supraspinatus and bicipital tendons and also rotator cuff lesions were identified. Clavicular osteolysis, avulsion injuries, muscle damage, and vertebral lesions were also noted. Several abnormalities revealed by scintigraphy were clinically unsuspected. CONCLUSIONS: Scintigraphic manifestations of several injuries, particularly around the shoulder, have a specific pattern. Recognition of these patterns can enhance the performance of bone scintigraphy. Scintigraphy also has the potential to detect clinically unsuspected disease.

A novel view for the scintigraphic assessment of the elbow.

Using any imaging modality, the elbow is a complex joint to evaluate. The use of scintigraphy in the evaluation of the effects of acute or chronic trauma has largely been confined to epicondylitis. We developed a skyline view of the elbow that minimized the effect of overlap and assessed its incremental value in the scintigraphic assessment of several pathological conditions. Thirty-four abnormalities were evaluated in 20 patients with a range of pathologies, including epicondylitis, ligamentous avulsion injury, articular injury, fractures and synovitis. The incremental value of addition of the skyline view to the standard views was assessed in addition to the overall accuracy of scintigraphy. Overall, scintigraphy detected 27 of 34 abnormalities, with the standard views of the elbow accurately identifying 15 and the skyline view 23 abnormalities. This gave the skyline view an incremental value of 24% over the standard views. In conclusion, scintigraphy has the potential to identify a greater range of pathologies in the elbow than previously reported, due to the addition of the skyline view to the standard views.

Rationalization of the optimal views in planar lung scintigraphy.

A knowledge of the segmental anatomy of the lungs is the cornerstone for interpreting lung scintigraphy. Many attempts have been made to determine the best views for the appreciation of segmental defects and various theories have been formulated to explain the mechanisms of this process. In earlier work, we hypothesized that the arrangements of the segments was the principal determinant of this process. However, data subsequently derived from work on a model of diffuse lung disease indicates that the external shape of the lobes and lungs may be the most significant contributor to the optimal views of the lungs.

Enhanced accuracy and reproducibility in reporting of lung scintigrams by a segmental reference chart.

UNLABELLED: The diagnostic probability of pulmonary embolic disease is based on the recognition of unmatched segmental perfusion defects. Although interobserver and intraobserver reproducibility have been studied, accuracy has been an elusive goal due to the lack of a gold standard. We investigated the accuracy and reproducibility of reporting in a virtual scintigraphic model of the lungs, with and without the use of a lung segmental reference chart. METHODS: A Monte Carlo package was used to model lung scintigraphy from a digital phantom of the human lungs. An ideal lung segmental reference chart was created from the phantom. Five experienced nuclear medicine physicians reported a set of all possible defects involving 100% of a segment, without and with the chart. A further set of defects involving 45%-55% of a segment in the lower lobes was investigated using the chart. RESULTS: There was a significant improvement in accuracy (from 48% to 72%) and intraobserver agreement (from 61% to 77%) with the chart. The accuracy of reporting defects in the upper and middle lobes was consistently better than that in the lower lobes. There was no significant difference between the accuracy of reporting large defects and that of reporting moderate defects in the lower lobes. CONCLUSION: The lung segmental reference chart significantly improves both the accuracy and reproducibility of reporting lung scintigrams; however, although reporting in the lung bases is improved, absolute accuracy is substantially less than that in the upper and middle lobes. This emphasizes the need for caution because the lung bases are the most common site of embolic disease.

Variability of perceived defect size in virtual lung scintigraphy.

UNLABELLED: The diagnosis of pulmonary embolism is based on the presence of mismatched segmental or subsegmental defects. An important axiom is the classification of defect sizes into small, moderate and large. Little information about the recognition and classification of such defects has been published. We undertook a study of the perception of defect size using a model of the virtual scintigraphic anatomy of the lungs to address this issue. METHODS: Segmental anatomy of the lungs was modeled with CT, cadaveric lungs and standard anatomical tests. The emission, scatter and attenuation of photons were modeled within these virtual lungs and the surrounding tissues. Single segmental lesions, each 100% of a segment, were created in eight projections and submitted for blinded reporting by four experienced nuclear medicine physicians to obtain their assessment of the size of each defect on two occasions. RESULTS: Of the 144 defects submitted for reporting, 15% were reported as <25% of a segment, 35% were reported as 25%-75% and 50% were reported as 75%-100%. The accuracy of each reporter and the intraobserver agreement were calculated; the weighted kappa value ranged from 0.34 to 0.60. The segmental defects that were most likely to be underestimated in size were in the right lower lobe. CONCLUSION: It is clear that segmental defect sizes were underestimated, particularly in the right lower lobe. Although the intraobserver agreement in reporting was fair, the accuracy of estimation was only 50%. The variability and inaccuracy might be reduced by the use of a guide to segmental anatomy.

Recognition of subsegmental scintigraphic defects in virtual lung scintigraphy.

A virtual model of the segmental scintigraphic anatomy of the lungs was used to investigate the threshold at which small defects are perceptible. A model of the segmental anatomy of the lungs was developed from a number of sources and counts generated within the phantom by Monte-Carlo simulation of photon emission. Multiple subsegmental defects were created in both lungs and submitted for blinded reporting to detect the presence of any defect. A total of 36 of the 47 (77%) defects were seen. Of those defects in the lower lobes, 16 of 22 (73%) were visible. All the defects in the left lung (n = 21) were visible, while 15 of 26 (58%) of the defects on the right were visible. In the lower lobe of the right lung, 4 of 10 defects were visible. The defects that were not visible were all in the right lung. We conclude that absolute size and location are critical in the perception of defects. The perception of defects was dependent on absolute defect size rather than the proportion of a segment involved. Defects less than 3% of the volume of a lung were not detected.

Simulation of the stripe sign in a scintigraphic model of the lungs.

Using a virtual model of the lungs, we investigated the nature of the 'stripe sign' which is sometimes encountered in pulmonary scintigraphy. A model of the segmental anatomy of the lungs was developed from a number of sources and counts generated within the phantom by Monte-Carlo simulation of photon emission. Multiple segmental and subsegmental defects were created in both lungs and submitted for blinded reporting of the 'stripe sign'. Images were resubmitted for reporting with the contralateral lung removed. The stripe sign was reported in 32 of the 117 studies performed. Nearly half of these were present in defects involving approximately 25% of a segment and the sign was most commonly seen in the lateral projection. Removal of activity from the contralateral lung abolished the sign in only 2 of 32 cases. We conclude that shine through of activity from the contralateral lung is a mechanism rarely responsible for the stripe sign. Most occurrences of the sign are due to interposition of activity from unaffected areas of the same lung between the defect and the periphery of the lung. Orientation of the segments, particularly in the lung bases, accounts for the lateral projection being the most common view in which the sign is present.

Pentavalent 99mTc DMSA: uptake into a variety of human rhabdomyosarcoma xenografts.

BACKGROUND: Rhabdomyosarcoma is a common soft tissue sarcoma of childhood. While Ga is currently the most accurate modality for imaging residual or recurrent tumour its dosimetry is unfavourable. Pentavalent 99mTc DMSA [99mTc (V) DMSA] has been shown to accumulate in this tumour in a limited number of clinical cases. METHODS: Biodistribution of 99mTc (V) DMSA was determined in non-tumour bearing BALB-C mice. Operative specimens from four clinically 67Ga avid tumours were xenografted into nude mice and allowed to reach a significant size. Biodistribution studies were performed after the injection of 99mTc (V) DMSA in all animals and 125I HSA and 67Ga in a limited number of animals. RESULTS: None of the tumours investigated demonstrated significant 99mTc (V) DMSA accumulation. Biodistribution was identical in tumour and non-tumour bearing animals. CONCLUSIONS: Rhabdomyo-sarcoma xenografts do not demonstrate significant uptake of 99mTc (V) DMSA.

Optimization of the scintigraphic segmental anatomy of the lungs.

UNLABELLED: Accurate and reproducible reporting of lung scintigraphy is predicated on a sound knowledge of the segmental anatomy of the lungs. A limited amount of hard data exists about the true segmental anatomy of the lungs. A virtual model of human lungs was created using a CT-based dataset and a Monte Carlo simulation technique to examine the optimal projections for the visualization of each segment in the lungs. METHODS: Segmental anatomy of the lungs was modeled using CT, cadaveric lungs and standard anatomical texts. The emission, scatter and attenuation of photons was modeled within these virtual lungs and the surrounding tissues. Single segmental lesions were created in eight projections and submitted for blinded reporting to four experienced nuclear medicine physicians to obtain the best views for each segment. RESULTS: The anterior and posterior oblique projections yielded the best views for 10 of 18 segments, with the laterals contributing four views, the anterior contributing two views and the posterior contributing one view. The majority of basal segments (six of nine) were best seen in the anterior and posterior oblique projections. CONCLUSION: This model overcomes the major problems associated with experimentation in the normal human and has the potential to provide answers to the major problems of scatter, attenuation and "shine-through" in lung scintigraphy.

Two cases of chronic recurrent multifocal osteomyelitis: radiological and scintigraphic findings.

Chronic recurrent multifocal osteomyelitis (CRMO) is an extremely rare condition, of uncertain aetiology. Since first described, in 1972, under 100 cases have been reported. It is being reported with increasing frequency, and many cases of this disease go unreported. It most commonly affects patients in childhood or adolescence. No infective agent has been identified, and antibiotics do not affect the course of the disease. We present the cases of two female children with this disorder, describe the radiological and scintigraphic findings and review the literature. Case 1 is the first reported case to our knowledge of CRMO presenting with cranial nerve palsies.

Multiple flexion-stress vertebral end-plate fractures. An osteogenesis imperfecta presentation.

A 28-year-old woman underwent bone scintigraphy for a 7-day history of severe back pain of sudden onset. Intense linear accumulation of Tc-99m HDP was present in several lower thoracic and lumbar vertebrae without vertebral body deformity. Intense uptake was also present in other thoracic vertebrae with vertebral body changes. X-rays demonstrated osteopenia and dual photon densitometry studies confirmed a significant degree of osteoporosis. Endocrine assessment identified that she and other female members of the family had osteogenesis imperfecta, Sillence type 1. This disorder should be considered in all differential diagnoses of nonobvious traumatic fractures of the vertebrae in healthy young adults.

Prominence of the C2 vertebra on SPECT. A normal variant.

Mild preferential focal uptake of Tc-99m HDP in the spinous process of C2 was identified with SPECT of the cervical spine performed in patients in whom the indication for bone scintigraphy was suspected of lesions in the limbs. Its presence in all 21 subjects indicates that such uptake is a normal finding.

The role of thallium scintigraphy in excluding malignancy in bone.

Scintigraphy with thallium-201 was performed on 22 patients in whom a solitary abnormality in bone was suspected of being malignant. In three patients, an additional lesion was subsequently identified. Preferential TI-201 uptake was found in 7 of 8 malignant lesions, but was absent in 16 of 17 abnormalities that proved to be benign. The use of TI-201 scanning is considered to offer high negative predictive value in the assessment of possible malignant change in bone.

The role of SPECT in the evaluation of skeletal trauma.

Single photon emission computed tomography (SPECT) has, in the last decade, established a critical role in routine diagnosis. Skeletal scintigraphy exemplifies the impact in improving detection of lesions by delineation of their site and size. The advantage of minimizing the superimposed radioactivity from overlying and underlying structures is typified by the readiness with which avascular necrosis of the femoral head can be identified by removal of the surrounding hyperaemia which masks the classical photopaenia. However, the ability to achieve an accurate image at a plane at a prescribed depth is most characteristically shown by the study of a vertebra, a bone of irregular contour and subject to a variety of pathological disorders at different sites within it. The various focal abnormalities resulting from these can be localized exactly, readily distinguishing, for example, those in the body from those in the natural arch. In particular, the alterations resulting from trauma, such as pars interarticularis stress fracture, are readily seen. Consequently SPECT has an indispensable role in the investigation and management of low back pain. However, the ability of SPECT to delineate abnormal accumulation has provided a new approach to the evaluation of knee pain, especially when acute such as that resulting from athletic injury, since the identification of the presence or absence of focal abnormalities can be critical to patient management. The frequency of these various disorders in which SPECT is so useful explains why the procedure has become such a routine high-volume examination is so many departments.