Accuracy in the diagnosis of mandibular involvement by oral cancer

Cancer of the mandibular region usually has a poor prognosis; this is particularly correlated to invasion of the mandible. To reduce the consequences of poor therapeutic planning, careful preoperative assessment of bone infiltration is necessary. We have examined the records of 50 patients evaluated by clinical examination, conventional radiography, computed tomography (CT), bone scintigraphy with 99mTc and magnetic resonance imaging (MRI). The highest sensitivity (100%) was attained by scintigraphy; the highest values of specificity (96.3%) were reached by CT scan and MRI. A CT scan showed the highest predictive positive value (95.4%) and efficiency (94%), this plus MRI have good values and the associated sensitivity and efficiency are higher than when these techniques are used alone.     

Morphological changes in chest radiographs of patients with acute respiratory distress syndrome (ARDS)

The value of ultrasonography (US), magnetic resonance imaging (MRI), computed tomography (CT) and plain radiography (PR) in detecting bone erosions on the humeral head was evaluated in a study of 26 in-patients (26 shoulders) with rheumatoid arthritis (RA). MRI depicted humeral erosions in 25 (96%), US in 24 (92%), CT in 20 (77%) and PR in 19 (73%) of the 26 shoulders. MRI and US were superior to CT in detecting small erosions. US was the most sensitive method to show surface erosions on the greater tuberosity. US, CT and MRI detected large erosions quite similarly. PR frequently missed small erosions. In the evaluation of early erosions in the rheumatoid shoulder, US and MRI are more sensitive methods than the traditionally used PR. US and MRI are suitable for the evaluation of soft-tissue involvement in the rheumatoid shoulder, but also for the detection of bone erosions of the humeral head.     

Vesicouterine fistula twenty years following brachytherapy for cervical cancer

Assessment of maternal pelvic dimensions is usually considered necessary where vaginal delivery is contemplated in a breech presentation or if reduced pelvic dimensions are suspected in a current or previous pregnancy. Pelvimetry techniques include computed tomography (CT), conventional radiography, digital fluorography and magnetic resonance imaging (MRI). The first three techniques result in a radiation dose to mother and fetus which, depending on how the technique is performed, can vary by up to 40-fold. Of the techniques using X-rays, CT pelvimetry with a lateral scanogram generally gives the lowest radiation dose and conventional radiography using an air gap technique with a single lateral view is a relatively low-dose alternative where CT is not available. A questionnaire was sent to 227 hospitals during 1993 and 1996 to assess whether there was a move towards lower dose techniques of pelvimetry. The results show a trend away from conventional pelvimetry (48.4% in 1993 to 28% in 1996) with a small proportion of centres using MRI (4%) in 1996. Of the centres still using conventional pelvimetry, relatively few were using a low-dose air-gap technique (2.1% in 1993 to 10.9% in 1996). An increasing majority of centres were using one-view CT (69.3% in 1993 and 80.4% in 1996) but a significant proportion were still performing more than one view. This study shows that there was a move towards lower dose techniques of pelvimetry but that there were still many hospitals that had not implemented a policy of reducing radiation exposure in these patients.     

Primary muscle lymphoma: clinical and imaging findings

PURPOSE: To assess the clinical and imaging findings in primary muscle lymphoma. MATERIALS AND METHODS: Seven patients with biopsy-proved primary muscle lymphoma without evidence of systemic disease underwent imaging with plain radiography or computed tomography (CT) and magnetic resonance (MR) imaging. Four underwent bone scintigraphy, and two underwent gallium scintigraphy and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) before and after therapy. RESULTS: Plain radiographs at initial examination (n = 5) showed no bone abnormalities. Soft-tissue masses and bone marrow involvement showed isoattenuation at CT (n = 3), but at MR imaging (n = 7), all masses demonstrated increased signal intensity on T2-weighted images that involved multiple muscle compartments and typically spanned a long segment of the extremity. Adjacent bone disease was less extensive than muscle disease, and, in most cases, subcutaneous stranding or extension was observed adjacent to the masses. Good size correlation was observed between findings at MR imaging, gallium scintigraphy, and FDG PET. Two patients developed recurrent multifocal muscle lymphoma several years after initial examination. CONCLUSION: The presence of an extensive soft-tissue mass with infiltration of adjacent subcutaneous fat and minimal or no extension into the bone marrow cavity at MR imaging and normal plain radiographic findings may suggest primary muscle lymphoma.     

Cerebellar deficient folia (cdf): a new mutation on mouse chromosome 6

OBJECTIVE: To discuss the case of an 8-yr-old boy with an aneurysmal bone cyst of the right proximal humerus, including the features imaged on plain film radiography, computed tomography (CT), magnetic resonance imaging (MRI), including spin echo and fast field echo imaging. CLINICAL FEATURES: The patient suffered for 1 yr from intermittent but progressive pain in his right upper arm and shoulder area. There was no history of trauma or known systemic disease. There was decreased range of motion in abduction of the glenohumeral joint and pain on focal pressure along the deltoid muscle. A complete imaging evaluation consisting of plain film radiography, CT and MRI was performed, which revealed the classical imaging features of an aneurysmal bone cyst. An additional cystic lesion was detected by the MRI that was not appreciated on the plain films or CT. INTERVENTION AND OUTCOME: The patient was referred for biopsy to confirm the preliminary diagnosis of aneurysmal bone cyst. No treatment was instituted. CONCLUSION: Evaluation of aneurysmal bone cyst may be completed with CT scanning and more specifically with MRI MRI coronal T2, weighted images are advantageous for visualization of the main cystic lesion and any additional cysts. Fast field echo images show a better contrast between the cyst and bone marrow with extension of the cyst into the epiphysis as evident in this case. Follow-up studies revealed complete healing of the cyst with only residual densities in the humeral metaphyseal area.     

Current indications and techniques in evaluating inflammatory disease and neoplasia of the sinonasal cavities

Imaging strategies of the sinonasal cavities have undergone extensive revision over the last 5-year period. The traditional imaging examination of the paranasal sinuses, plain film radiography, does reasonably well in diagnosing maxillary, frontal, and sphenoid sinusitis. However, it less reliable in depicting abnormalities in the ethmoid sinuses, the most common area first affected with inflammatory disease. Compared with sinus computed tomography (CT), plain films prove to be less specific and sensitive in depicting the extent of sinus abnormalities. One series plainly concluded that sinus radiographs were not reliable enough to be an integral part of the clinical decision process. The use of plain radiographs of the sinuses has clearly been reduced by medical cost-containment concerns, replacement by superior techniques, and by clear weaknesses of the modality. Although it is inexpensive and easily accessible, the low sensitivities and inaccuracies of plain film radiography have resulted in the current use of CT and high-field-strength (1.5 Tesla) magnetic resonance imaging (MRI). By using this cross-sectional imaging, we now visualize directly the pathologic conditions within the sinuses, as well as the normal anatomy. We discuss current use of diagnostic imaging in the evaluation of patients with nasosinusoidal complaints (most commonly resulting from acute and chronic inflammatory disease), with complications of sinonasal inflammatory disease, and with suspected/documented neoplasia. In addition to developing an imaging algorithm to provide the information affecting clinical decision making, we detail the specific imaging techniques necessary accurately to obtain that information. We also review the specific concerns about imaging patients in the intensive care unit and touch on several emerging imaging techniques. The imaging workup in pediatric patients and patients with congenital anomalies is beyond the scope of this review.     

MRI in the diagnosis of osteoid osteoma

INTRODUCTION: Osteoid osteoma (OO) is a frequently encountered benign bone tumor, seen in young adults with male predominance. MATERIALS AND METHODS: Nine patients complaining of nonspecific extremity pain underwent MRI examination. The sequences obtained were T1 and T2 weighted spin-echo and T2 weighted gradient echo. A CT scan examination followed in all cases, exploring the region of the abnormal signal seen on MRI. The results of both examinations were compared. RESULTS: In six of the nine patients (66.6%) MRI showed evidence suggestive of osteoid osteoma, comparable that seen on CT scan. In three patients (33.3%), MRI showed a nonspecific and ill-defined bone marrow signal abnormality. CT cuts focused on those areas of signal abnormality showed the nidus. DISCUSSION: MRI is more sensitive than CT scan in detecting soft tissue and bone marrow abnormalities adjacent to an osteoid osteoma. This may produce a misleading aggressive appearance on MR images. CT scanning is more specific than MRI, by showing the nidus. In three patients studied, the nidus was only seen by CT, the other six osteoid osteomas were equally seen by CT and by MRI. In our study, MRI revealed abnormalities in all the cases. It was also highly specific for osteoid osteoma in 66.6%. CONCLUSION: MRI is very sensitive in detecting bone marrow and soft tissue abnormalities, and can suggest the diagnosis of OO in a good number of patients. In the remainder cases MRI guides the CT-scan. CT is more accurate and remains the definite examination for the diagnosis of OO, by showing the nidus.     

Patterns of ordering diagnostic tests for patients with acute low back pain. The North Carolina Back Pain Project

BACKGROUND: Low back pain is a common reason for visiting a physician. Authors of guidelines and insurance payers are currently scrutinizing use of radiography and computed tomography (CT) or magnetic resonance imaging (MRI). OBJECTIVE: To study the determinants of the use of lumbar spine radiography and either CT or MRI in patients with acute low back pain. DESIGN: Prospective cohort study. SETTING: Community-based practices in North Carolina in six strata: urban primary care physicians, rural primary care physicians, urban chiropractors, rural chiropractors, orthopedic surgeons, and practitioners at a group-model health maintenance organization. PATIENTS: 1580 patients with acute low back pain. MEASUREMENTS: Telephone interviews done after the index office visit and at 2, 4, 8, 12, and 24 weeks or until complete recovery; survey of practitioners; and chart abstraction. RESULTS: During the acute back pain episode, 46% of patients had radiography and 9% had CT or MRI. Patient variables related to use of radiography included pain that began more than 2 weeks before the index visit and no previous episodes of low back pain. Practitioner variables associated with use of radiography were being a chiropractor or orthopedic surgeon and having a solo practice. Use of CT or MRI was associated with white race, neurologic deficit at baseline, sciatica, poor functional status at baseline, and small group-practice size. Practitioners' responses to clinical vignettes were associated with aggregate practitioner behavior: In the vignettes and in real life, practitioners were more likely to order CT for patients with sciatica. However, a practitioner's response to a vignette did not predict that practitioner's use of CT or MRI for similar patients in his or her own practice. CONCLUSION: Radiography is commonly used as a diagnostic test for patients with acute back pain. Clinical factors and provider specialty are major correlates of the use of imaging studies.     

Evaluation of the skull base by SPECT. A comparison with planar scintigraphy and computed tomography

Computed tomography is currently the standard diagnostic tool for the evaluation of the skull base. The complex anatomy of this area is the primary reason why planar bone scintigraphy is often unsatisfactory; exact localization of abnormalities may be very difficult. These limitations may be overcome by SPECT. Seventeen patients with clinical features of basal skull involvement were assessed by CT, SPECT, and planar scintigraphy. Subsequent clinical diagnoses were malignancy in 15 patients, vasculitis in 1 patient, and osteomyelitis in 1 patient. Computed tomography with IV contrast was performed through the skull base at 5 mm intervals. Planar scintigraphy with Tc-99m MDP was followed by SPECT. Bony involvement compatible with the clinical findings was demonstrated by CT scans in 6 patients, by planar scintigraphy in 7 patients, and by SPECT in 9 patients. The abnormalities that were identified by CT were all identified by SPECT. This study suggests that, in imaging the skull base, SPECT is more sensitive and provides better anatomical localization than planar imaging and appears useful in patients with a negative CT study.     

Iodine-131 metaiodobenzylguanidine scintigraphy for localization of lesions in children with neuroblastoma: comparison with computed tomography and ultrasonography

Iodine-131 metaiodobenzylguanidine (MIBG) scintigraphy, computed tomography (CT) and ultrasonography (US) were used to localize tumour lesions in 28 children with histologically proven neuroblastoma. Overall, a total of 73 lesions were detected on imaging studies. MIBG scintigraphy, CT and US localized 63 (86%), 49 (67%) and 36 (49%) of these lesions, respectively. The findings of the three imaging techniques were concordant in respect of only 31 (42%) of the lesions. The best agreement among MIBG scintigraphy, CT and US was observed for abdominal lesions (the techniques were concordant for 22 of 23 lesions, i.e. 96%). MIBG scintigraphy detected nine out of ten (90%) liver metastases, but agreement with CT and US was observed in only six instances (60%). The imaging findings were concordant in respect of only two (33%) out of six lymph node metastases; the MIBG scan was normal in the other four cases. Imaging agreement was observed for a lesion located in the pelvis. MIBG and CT findings were concordant in four lesions located in the chest, but US was not performed. MIBG scintigraphy depicted the majority (96%) of the skeletal lesions (23/24); CT showed five of these, but, again, US was not performed. The imaging findings were not concordant as regards the remaining five lesions located in different anatomical sites. The results indicated that MIBG imaging is more sensitive that CT and US in localizing the majority of neuroblastoma lesions. Since the metastatic spread of neuroblastoma is unpredictable, we recommend MIBG scintigraphy as the initial imaging modality for staging of these patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

MRI of the foot and ankle

The foot and ankle are among the hardest of all areas to image because of the complex three-dimensional anatomy. Magnetic resonance imaging (MRI), with its multiplanar capabilities, excellent soft-tissue contrast, ability to image bone marrow, noninvasiveness, and lack of ionizing radiation, has become a valuable tool in evaluating patients with foot and ankle problems. MRI is more specific than bone scintigraphy and provides more information than ultrasound and computed tomography. Arthroscopy of the ankle is limited to the articular surface and joint space. MRI allows a global evaluation of the bones, tendons, ligaments, and other structures with a single examination that exceeds the capabilities of all other available techniques. This monograph was written to provide a useful guide to basic technique, indications, positioning, anatomy, and interpretation of foot and ankle MRI. The first part describes the performance of the MRI examination with reference to the positioning of the foot, types of coils, and advantages and disadvantages of the different sequences and imaging planes. The next section was written by an experienced foot and ankle orthopedic surgeon and outlines the indications for MRI for the common foot and ankle symptom complexes and the information that the surgeon hopes to obtain from the study. This is followed by a review of pertinent anatomy, as it applies to imaging, with emphasis on osseous structures, ligaments, tendons, and muscles. The final section is a comprehensive review of the common pathologic conditions encountered in the foot and ankle. We hope that radiologists and radiologists-in-training find this article a useful reference tool and gain a better understanding of this complex area of musculoskeletal imaging.     

Activity of pentamidine-loaded poly (D,L-lactide) nanoparticles against Leishmania infantum in a murine model

Tumors of craniocervical junction (ccjct) may cause a variety of non specific signs and symptoms. Before the advent of computed tomography (CT) diagnosis was sometimes possible only by surgical exploration, as the available radiologic methods--plain film radiography, angiography, and myelocisternography--essentially provided only indirect information about the neural structures. Because of its beam hardening artifacts, CT remained unsatisfactory as well. These diagnostic problems have practically disappeared with the availability of magnetic resonance imaging (MRI), which is now considered the method of choice if a space-occupying lesion is suspected at the ccjct. In some cases invasive angiography may still be necessary for surgical planning, and angiography may also be needed, whenever CT or MRI suggest the presence of an aneurysm. In the first part of this overview we present strategies for the radiological examination of the ccjct.     

99mTc-HMPAO labeled leukocyte SPECT in intracranial lesions

BACKGROUND: Scintigraphy with 111In (indium-111)-oxine or 99mTechnetium-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled leukocytes has been used to differentiate brain abscess from brain tumor. However, there are false positive or false negative results from planar scintigraphic images. So a more specific and sensitive scintigraphic technique needs to be developed. METHODS: Planar and single photon emission computed tomography (SPECT) images were obtained and reviewed in 14 patients with intracerebral ring-enhancing lesions on computed tomography (CT) or magnetic resonance imaging (MRI). In all patients, diagnosis was confirmed by histopathologic examination. The effect of steroids or antibiotics on scintigraphic finding was examined. RESULTS: Abscess was confirmed in six patients, tumor in six, tuberculoma and cysticercosis in one each, respectively. In all the patients with abscess, SPECT showed increased focal activity irrespective of steroid or antibiotic therapy. Increased radioactivity, which could not be detected on planar images, could be identified in two patients with abscess. In three of the six patients with tumor, radiolabeled leukocytes did not accumulate in the tumor. In the other three patients with tumor, SPECT showed focally increased activity that was less intense than the activity shown in the patients with abscess. CONCLUSIONS: 99mTc-HMPAO labeled leukocyte SPECT is useful for the differential diagnosis of intracerebral ring-enhancing lesions, and the use of steroids or antibiotics does not influence the sensitivity of SPECT. Diagnostic sensitivity of scintigraphy with labeled leukocytes could be improved by SPECT in addition to planar image.     

Radiographic evaluation of osseous displacement following intra-articular fractures of the distal radius: reliability of plain radiography versus computed tomography

This study evaluated the reliability of plain radiography versus computed tomography (CT) for the measurement of small (< 5 mm) intra-articular displacements of distal radius fracture fragments. The plain radiographs and CT scans of 19 acute intra-articular distal radius fractures were used by 5 independent observers, using 2 standardized techniques, to quantify incongruity of the articular surface in a blinded and randomized fashion. Repeat measurements were performed by the same observers 2-4 weeks later, allowing determination of intraclass correlation coefficients (ICC) as a measure of intraobserver and interobserver agreement. The average maximum gap displacement on plain radiographs was 2.1 mm (range, 0.0-15.0 mm, lateral view) and on CT images was 4.9 mm (range, 0.7-17.3 mm, axial view). The average maximum step displacement on plain radiographs was 0.9 mm (range, 0.0-6.4 mm, lateral view) and on CT images was 1.2 mm (range, 0.0-6.0 mm, sagittal view). More reproducible values determining step and gap displacement were obtained when the arc method of measurement was used on CT scans (ICC values, .69-.97) as compared to the longitudinal axis method for plain radiographs (ICC values, .30-.50). For measured displacements of 2 mm or more, our data demonstrated poor correlation between measurements made on CT images and those made on plain radiographs (gap or step displacement > 2 mm, K = 0.21; step displacement > 2 mm, K = 0.21). Thirty percent of measurements from plain radiographs significantly underestimated or overestimated displacement compared to CT scan measurements. From these data, we conclude that CT scanning data, using the arc method of measurement, are more reliable for quantifying articular surface incongruities of the distal radius than are plain radiography measurements.     

Cisternography in combination with single photon emission tomography for the detection of the leakage site in patients with cerebrospinal fluid rhinorrhea: preliminary report

The site of leakage in a patients with rhinorrhea of various origin may be difficult to identify. The aim of our paper is to evaluate the contribution of cisternography in combination with single photon emission tomography (SPECT) to identify the fistulous track. From 1/1/1992 to 30/11/1997 we studied 20 patients with rhinorrhea posing a challenging diagnostic problem as to identification of the leakage site. Two mls of Indium DTPA (In 111) were injected into the subarachnoid space by the lumbar route. The tracer was followed by planar scintigraphy until it reached the cranial base and subsequently the SPECT acquisition started. A fistula was demonstrated in all of our cases including patients with no active leakage at the time of examination, patients with no bone defects on thin sliced CT scanning or patients with a normal MRI. At surgery the fistulous track was confirmed in all but two cases when a bilateral fistula was operatively identified only on one side. In conclusion whenever a CT scanning fails to demonstrate significant bone defects and MRI does not localize a fistulous track, SPECT cisternography via the lumbar route proved in our experience to be a reliable examination for a precise diagnosis.     

The coexistence of 2 different neuroendocrine tumors of the upper gastrointestinal tract and pancreas

HISTORY AND CLINICAL FINDINGS: A 41-year-old obese patient presented with cramp-like abdominal pain, watery diarrhoea with partly digested food particles, projectile vomiting and newly diagnosed diabetes mellitus. For the preceding 6 years he had been treated for recurrent gastric and duodenal ulcers. Although the fasting gastrin level was raised and Zollinger-Ellison syndrome suspected, computed tomography (CT), magnetic resonance imaging (MRI) and coeliac angiography at another hospital had failed to discover a tumor. INVESTIGATIONS: Biochemical tests were unremarkable except for an increased GPT concentration, slight fasting hyperglycemia and hypertriglyceridemia. The gastrin and chromogranin A levels were markedly elevated (15,590 pg/ml and 584.2 U/l, respectively). Gastroscopy revealed, in addition to multiple small duodenal ulcers, a round polypoid mass (diameter of 0.7 cm) lateral to the papilla of Vater, histologically an APUDoma. Endoscopic retrograde cholangiopancreatography (ERCP) revealed a 0.5 cm long compression of the duct of Wirsung in the region of the head of the pancreas. Liver metastases were excluded by magnetic resonance imaging and computed tomography. Endosonography showed a ca. 4 mm space-occupying lesion in the region of the body of the pancreas. Octreotide scintigraphy demarcated two foci at the level of the head of the pancreas (somatostatin-receptor positive). TREATMENT AND COURSE: After a pylorus-preserving partial duodenopancreatectomy with lymph node dissection N1/N2, histology confirmed a gastrinoma of the duodenum and a glucagonoma of the pancreas (pT3pN1pMx). Postoperatively the patient became symptom-free and both the blood sugar level and the tumor marker were normal. CONCLUSION: Combined ERCP, endosonography and scintigraphy are more sensitive than other radiological examinations (CT and MRI) in diagnosing and localizing neuroendocrine tumours of the gastrointestinal tract. Despite the low incidence of such tumours, the possible synchronous occurrence of several such tumour should not be ignored.     

Imaging and lung disease: uses and interpretation

Diagnostic imaging has undergone a profound revolution since the first computed tomography (CT) unit was conceived in 1971; CT is now an integral part of daily practice in thoracic radiology, and has reached a relative technological maturity. Magnetic Resonance Imaging (MRI) has been introduced more recently. Technical difficulties still exist and are related to cardiac and respiratory motion. The storage-phosphor-based computed radiography system provides several advantages, including compensation for variations in exposure, but is still under evaluation especially in bedside radiography. Nevertheless careful plain film analysis still remains an important examination, and should be done before special procedures are taken to answer specific questions. Routine chest radiography is still the most frequent method of imaging employed today. Radiographic studies can suggest airway pathology such as atelectasis, endobronchial neoplasia or bronchiectasis, but CT provides a unique strategy for the localization and characterization of bronchial and pulmonary parenchymal disease. The most important role of CT is to determine, localize and characterize patterns within the pulmonary parenchyma, and correctly identify bronchiectasis even when bronchography is equivocal. In lung cancer, imaging has an important role in accurate staging with regard to the correct selection of patients and evaluation of prognosis. CT is one of the major tests used for staging. The staging system now adopted worldwide is based upon AJCC and ATS classification, and has two major components: anatomic extent of the disease (TNM) and cell types. The role of MRI with regard to lung cancer is not precisely determined. MRI can play a complementary role in the staging of lung cancer in cases of superior sulcus tumour; pericardial involvement, tumoral extension in subcarinal region and invasion of the superior vena cava. The radiologic detection of the solitary nodule is a difficult charge for the radiologist; CT provides the precise localization of the nodule and is reliable for analysing radiologic features such as calcification, cavitation, and spiculated borders. The problem remains of the discovery of an incidental benign pulmonary nodule in the patient with an extrathoracic malignancy, and often necessitates percutaneous biopsy under CT guidance. The evaluation of diffuse lung disease lies on pattern recognition. Chest radiography is the initial tool for diagnosis, high resolution CT (HRCT) can provide routine visualization of structures of less than 500 mu. HRCT can be useful in formulating a differential diagnosis with recognition of pattern and distribution of the disease.(ABSTRACT TRUNCATED AT 400 WORDS)     

A review of the recent advances in magnetic resonance imaging in the assessment of osteoporosis

Osteoporosis is a common metabolic disorder with considerable associated morbidity and mortality. The loss of bone mineral integrity and the resultant occurrence of atraumatic fractures are typically symptomatic of the disease. Currently skeletal status is commonly assessed using non-invasive conventional radiography and scintigraphy as well as densitometric techniques such as quantitative computed tomography and dual-energy X-ray absorptiometry. But, apart from gross bone mineral density, the fine structure of trabecular bone also plays an important role in defining the biomechanical competence of the skeleton. Recently attention has been focused on deriving measures that provide information about not only trabecular bone density but also microstructure. Magnetic resonance imaging (MRI) is one such new technique which potentially may provide information pertaining to bone density and structure as well as to occult fracture detection. Cortical bone produces a signal void in MR images, due to the fact that it contains very few mobile protons that give rise to a signal in MRI; also the MR relaxation time T2 of these protons is very short which produces a very fast decay of the MR signal during image acquisition. However, the trabecular bone network affects the MR properties of bone marrow. The difference in the magnetic properties of trabecular bone and bone marrow generates local imperfections in the magnetic field. The MR signal from bone marrow is modified due to these imperfections and the MR relaxation time T2 of marrow is shortened. The extent of relaxation time shortening and hence loss of signal intensity is proportional to the density of trabecular bone and marrow interfaces and their spatial architecture. Recent investigation in this area include studies aimed at quantifying marrow relaxation times and establishing their relationship to trabecular bone density and structure. In addition, with advances in imaging software and hardware, MR images at in-plane resolutions of 78-200 microns may be obtained. The trabecular bone structure is clearly revealed in such images and studies aimed at the development of high-resolution MRI techniques combined with quantitative image analysis techniques are currently under way. These potentially useful techniques for assessing osteoporosis and predicting fracture risk are reviewed in this paper.     

Detection of metastatic bone lesions in patients with prostate carcinoma: 99Tcm-monoclonal antibody imaging

Bone scintigraphy has been shown to be sensitive in determining bone involvement in patients with malignancy, but it does not allow the assessment of bone marrow lesions in early disease. The aim of this study was to detect bone marrow invasion using 99Tcm-labelled monoclonal antigranulocyte antibody (AgMoAb) in patients with prostate carcinoma. We studied 56 patients whose mean (+/- S.D.) age was 67 +/- 7 years. The mean prostate-specific antigen level was 6.1 ng ml-1 (normal range 0-5 ng ml-1). Twelve patients were in stage A, 16 in stage B, 17 in stage C and 11 in stage D. Six patients had been receiving chemotherapy and four patients radiotherapy before scanning. Bone scans were obtained 2 h after the intravenous injection of 555 MBq 99Tcm-methylene diphosphonate (99Tcm-MDP). Within a week, bone marrow imaging was performed 4 and 24 h after the injection of 555 MBq 99Tcm-AgMoAb. Metastatic bone lesions were detected on the 99Tcm-MDP scans of 14/56 (25%) patients, of whom one was in stage A, two in stage B, four in stage C and seven in stage D. Hypoactive lesions in bone marrow were detected in 25/56 (45%) patients, of whom two were in stage A, five in stage B, seven in stage C and 11 in stage D. Bone marrow metastases were confirmed in six patients by computed tomography (CT) and magnetic resonance imaging (MRI) and in two patients by marrow aspiration biopsy. A false-positive immune scintigram was found in three patients previously receiving radiotherapy or chemotherapy. We suggest that 99Tcm-AgMoAb scintigraphy is a sensitive procedure for the detection of bone marrow lesions. However, the reason for false-positive and false-negative results should be considered and CT, MRI and marrow biopsy should be performed when clinically necessary.     

Cardiac rhabdomyosarcoma: a clinicopathologic and electron microscopy study

The use of imaging techniques including gamma scintigraphy to follow the behaviour of drug formulations has revolutionized our knowledge of absorption and distribution in drug delivery. The development of gamma camera techniques as physiological tools to explore organ function became routine by the mid-seventies. Several research groups started to explore the applications of technique in drug delivery. Within 5 years, the utility of the technique became obvious and scintigraphy is now widely accepted as an important investigation tool in formulation research. Gamma scintigraphy is especially useful in exploring sources of inter-subject variation, especially in examining food effects in pharmacokinetic estimations and establishing windows of absorption for oral delivery. As a tool to examine drug delivery to the lung and to the eye, scintigraphy is the method of choice. Magnetic Resonance Imaging (MRI) became more generally employed in medicine two decades after the gamma camera. The superior soft-tissue contrast and resolution compared to computed X-ray tomography rapidly established MRI in clinical investigation. Recent applications in oral drug research has allowed the pharmaceutical scientist to explore new facets of delivery and ultimately combine MRI and scintigraphy in human clinical trials.