Magnetic resonance imaging of renal lymphoma with computed tomography correlation

The magnetic resonance (MR) imaging and computed tomography (CT) findings in four patients (five kidneys) with non-Hodgkin's lymphoma involving the kidneys and perirenal spaces are presented. The patterns of disease in each case were as follows: bilateral renal nodules, infiltration in the perirenal space, infiltration in the perirenal space with renal involvement, and direct invasion from contiguous retroperitoneum. On plain CT, the lesions showed slight hyperdensity (three kidneys) and isodensity (two kidneys) as compared with normal renal parenchyma. But all lesions appeared as hypodense masses with more definite margins after contrast enhancement. MR imaging findings showed iso- or slight hypointense masses on T1-weighted images and definite hypointense masses on T2-weighted images as compared with the signal intensity of the renal cortex. Dynamic imaging and conventional delayed T1-weighted imaging following Gd-DTPA injection showed no significant enhancement of the lesions. In comparison with contrast enhanced CT, despite its poorer resolution, T2-weighted MR imaging showed nearly the same accuracy in the evaluation of number and extent of the lesions without contrast medium administration. MR imaging was also useful to evaluate the patency of vessel lumen surrounded by tumor mass and to determine the location and extent of huge lesions by its multiplanar imaging capabilities.     

The SPINRPHEX club

A 3-year-old Japanese domestic cat with a diagnosis of lymphocytic leukemia showed severe generalized seizures in the course of chemotherapy after leukemic condition was improved clinically. Computed tomography (CT) and magnetic resonance (MR) imaging of the brain were carried out. Both contrast procedures disclosed enhancements at the falx cerebri and the margin of cerebral cortex. Among these procedures contrast MR imaging demonstrated the lesion most clearly. Cytological examination of cerebrospinal fluid obtained by spinal puncture showed the infiltration of malignant cells and the diagnosis of meningeal syndrome associated with lymphocytic leukemia was defined. Intrathecal administration of cytosine arabinoside partially improved the neurologic dysfunction. Autopsy and histopathological examination confirmed the infiltration of leukemic cells in the areas of meningeal lesion demonstrated with contrast CT and MR imaging. Thus these imaging techniques, especially contrast MR imaging, are useful tools for rapid and precise diagnosis of meningeal syndrome.     

Electron transfer kinetics at a biotin/avidin patterned glassy carbon electrode

STUDY DESIGN: Comparison of findings in plain radiography and conventional tomography with findings in plain radiography and magnetic resonance imaging of the upper cervical spine in consecutive patients with rheumatoid arthritis and with known or suspected abnormalities of the cervical spine. OBJECTIVES: To determine whether plain radiography and magnetic resonance imaging provide enough information to dispense with tomography in investigations of cervical spine involvement in rheumatoid arthritis. SUMMARY OF BACKGROUND DATA: With the recent advances in magnetic resonance imaging technology and the proliferation of magnetic resonance imaging techniques for specific clinical conditions. METHODS: Twenty-eight patients with rheumatoid arthritis and with known or suspected abnormalities of the cervical spine underwent a clinical neurologic examination; plain radiography, including full flexion lateral radiography; anteroposterior and lateral tomography at C1-C2; and magnetic resonance imaging at the same level in neutral position and in flexion. Two radiologists evaluated one image set consisting of plain radiography and conventional tomographic images and another image set consisting of plain radiography and magnetic resonance images, for each patient. RESULTS: Compared with conventional tomography and plain radiography, magnetic resonance imaging and plain radiography showed cystic lesions and erosions of the odontoid process and vertical atlantoaxial subluxation more often, showed anterior subluxation as often, and showed lateral atlantoaxial subluxation less often. CONCLUSION: Magnetic resonance imaging produces sufficiently distinct images of destruction of the odontoid and subluxations for it to replace conventional tomography in investigations of upper cervical spine involvement in rheumatoid arthritis.     

Magnetic resonance imaging of focal liver lesions. Comparison of the superparamagnetic iron oxide resovist versus gadolinium-DTPA in the same patient

RATIONALE AND OBJECTIVES: The authors assess the efficacy of static and dynamic magnetic resonance (MR) imaging using the superparamagnetic iron oxide SHU-555A (Resovist) versus standard dose of gadolinium (Gd)-DTPA in patients with focal liver lesions. METHODS: Magnetic resonance imaging was performed in 30 patients suffering from histopathologically verified malignant (n = 22) and benign (n = 8) liver lesions. T2-weighted conventional and fat-suppressed as well as T1-weighted sequences were used before, during, and after fast intravenous administration of Resovist (1 mL/minute) at three doses of 4, 8, and 16 mumol/kg body weight. One week before the Resovist-enhanced MR imaging study 20 patients underwent Gd-DTPA-enhanced MR imaging. RESULTS: Detection rate was improved for metastatic lesions revealing 36 lesions unenhanced versus 53 focal lesions using Resovist-enhanced MR imaging. Gadolinium-DTPA-enhanced scans showed no additional lesion versus unenhanced and Resovist-enhanced MR imaging. Static and dynamic imaging demonstrated no measurable percentage signal intensity loss (PSIL) using Resovist-enhanced MR imaging versus a percentage enhancement of 79.7% in Gd-DTPA enhanced scans. In the dynamic T2-weighted sequences, hepatocellular carcinoma nodules (n = 4) showed a rapid decrease in signal intensity starting at 44 seconds. Postinfusion of Resovist followed by a low, constant increase in signal intensity. Gadolinium-DTPA enhanced scans showed a percentage enhancement of 73.4 focal nodular hyperplasia (FNH) and hemangioma revealed a strong and early dose-dependent PSIL 44 to 60 seconds postinfusion with a prolonged signal loss for the FNH in the late study. Statistical evaluation revealed a statistically significant superiority of Resovist-enhanced MR imaging concerning the detection and delineation of focal liver lesions compared with unenhanced and Gd-DTPA enhanced scans (P < 0.05). CONCLUSIONS: The fast infusion of the new superparamagnetic contrast agent Resovist shows advantages for dynamic and static MR imaging of focal liver lesions.     

Evaluation of tibial plateau fractures: efficacy of MR imaging compared with CT

OBJECTIVE: CT is often used after plain films to evaluate fractures of the tibial plateau. Because MR imaging can show associated soft-tissue injuries as well as fractures, we hypothesize that MR is superior to CT for imaging these injuries. Accordingly, we compared the efficacy of MR imaging and CT in 22 patients with tibial plateau fractures. SUBJECTS AND METHODS: CT with two-dimensional reconstruction and MR examinations were performed in 22 patients with tibial plateau fractures. The images were interpreted by four radiologists and two orthopedic surgeons. Findings on CT scans and plain films were used to determine the configuration of the fractures and to classify them according to the Schatzker system. This was done with findings on MR images and plain films at a separate session. The MR images were also evaluated for ligamentous and meniscal injuries. A qualitative side-by-side comparison of two-dimensional CT scans and MR images for depiction of fracture configuration was done. Imaging results were correlated with observations from physical examinations in all patients and with surgical findings in 12 patients. RESULTS: All of the six types of fractures of the Schatzker classification were observed in this series. Comparison of two-dimensional CT reconstructions and MR images for depiction of fracture configuration revealed that the two techniques were equal in 14 patients, MR imaging was superior to CT in five patients, and CT was superior to MR imaging in three patients (who had very complex and comminuted fractures). In addition, MR imaging showed 12 complete ligamentous tears and 15 partial ligamentous tears in 15 (68%) of the 22 patients. MR showed meniscal injuries in 12 (55%) of the 22 patients. CONCLUSION: MR imaging was equivalent or superior to two-dimensional CT reconstruction for depiction of fracture configuration in most patients. In addition, MR showed significant soft-tissue injuries. We believe that MR imaging is the preferable imaging technique for most patients with fractures of the tibial plateau.     

Autologous transplantation of peripheral hematopoietic cells in a patient with multiple myeloma and renal insufficiency

A 28-year-old man had recurrent episodes of headache, ophthalmoplegia, and ptosis. MR imaging showed a mass within the sphenoid sinus. TI-201 imaging showed intense uptake in the region of the sphenoid sinus and right middle fossa with moderate retention of activity, suggesting the diagnosis of a viable tumor. A biopsy specimen from the sphenoid sinus revealed dense inflammatory infiltrate dominated by plasma cells, consistent with inflammatory pseudotumor. After radiation therapy, the mass showed no significant change on MR imaging, but regressed in size and uptake on the follow-up TI-201 scan. TI-201 may accumulate in nonmalignant inflammatory lesions and could mimic a viable tumor. It is, therefore, suggested that before surgery and histologic diagnosis, any abnormal intracranial accumulation of TI-201 should be interpreted with caution.     

New frontiers in the management of obstructive sleep apnoea syndrome

BACKGROUND: To report the dynamic magnetic resonance (MR) imaging findings of hepatolithiasis. METHODS: Dynamic MR images (fast spoiled gradient echo sequence with intravenous injection of gadopentate dimeglumine) and computed tomography, cholangiography, or angiography of nine patients with hepatolithiasis are analyzed. RESULTS: All affected hepatic segments showed atrophic changes and contained dilated intrahepatic ducts. These segments showed either iso- or hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging. Preferential enhancement was noted throughout all phases of the dynamic study and persisted to delayed T1-weighted imaging in seven patients. In the last two patients, severe atrophic changes made evaluating signal intensity differences and enhancement patterns difficult. CONCLUSION: In addition to intrahepatic stones and biliary dilatation, segmental atrophy, signal intensity differences, and preferential and persistent enhancement are important MR findings of hepatolithiasis.     

Imaging studies in a unique familial dysmyelinating disorder

We report the imaging findings in five patients with a unique dysmyelinating disorder. MR studies of these infants showed obstructive hydrocephalus caused by mass effect produced by an enlarged cerebellum. The white matter of an enlarged cerebrum and cerebellum showed delayed myelination. Proton spectroscopy showed normal N-acetylaspartate (NAA) levels. While the dysmyelinating disorder was clearly differentiated from Canavan disease by an absence of elevated NAA and differing histopathologic findings and autosomal-dominant inheritance pattern, there were similarities to this disease in the presentation and, to some extent, in the initial imaging findings.     

Recurrent acute transverse myelopathy associated with anticardiolipin antibodies

In three patients with recurrent episodes of acute transverse myelopathy, spinal MR imaging during each episode showed areas of hyperintensity on proton density- and T2-weighted images with inconsistent contrast enhancement. Cranial MR imaging, laboratory screenings, and CSF analysis showed only increased titers of anticardiolipin antibodies. Although a causative role in neurologic conditions has not been established conclusively, an association between these antibodies and acute transverse myelopathy and its recurrences cannot be ignored.     

Phenylketonuria: findings at MR imaging and localized in vivo H-1 MR spectroscopy of the brain in patients with early treatment

PURPOSE: To characterize white matter changes in early-treated phenylketonuria (PKU) with magnetic resonance (MR) imaging and hydrogen-1 MR spectroscopy and to correlate these findings to biochemical control and brain function. MATERIALS AND METHODS: Fifty-one patients aged 12-33 years underwent T1-, T2-, and proton-density-weighted MR imaging and testing of intelligence, visual evoked potentials (VEPs), and neuropsychologic status (29 adult patients only). H-1 MR spectroscopy was performed in eight patients to determine brain metabolite concentrations, including phenylalanine (PHE) concentration, and brain compartmentation. RESULTS: MR imaging revealed a high frequency of supra- and infratentorial abnormalities. MR imaging grade, which was based on areas of high signal intensity on T2-weighted images, showed statistically significant correlation with long-term biochemical control and neuropsychologic test results but not with intelligence quotient or VEPs. H-1 MR spectroscopy revealed normal metabolite levels, except for increased PHE levels. It also showed enlarged cerebrospinal fluid-like compartments in affected white matter, related to plasma and brain concentrations of PHE and MR imaging grades. CONCLUSION: A synergistic use of MR imaging and MR spectroscopy may help elucidate both the pathogenesis of brain dysfunction and clinical treatment policies in PKU.     

Spontaneous drainage of syringomyelia. Report of two cases

Two cases are reported of Arnold-Chiari type I malformation associated with syringomyelia, in which magnetic resonance (MR) imaging revealed spontaneous decompression of the syrinx. In one case axial MR imaging sections showed a communication between the syrinx and the spinal subarachnoid space, which supports the hypothesis that fissuring of the cord parenchyma is instrumental in the spontaneous resolution of syringomyelia. The MR imaging changes were not accompanied by variations in the patients' clinical course.     

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.     

Preoperative staging of endometrial carcinoma: diagnostic effect of T2-weighted fast spin-echo MR imaging

PURPOSE: To evaluate the usefulness of T2-weighted fast spin-echo magnetic resonance (MR) imaging with a 512 x 256 matrix for assessment of the preoperative stage of endometrial carcinoma. MATERIALS AND METHODS: Twenty-eight women with histopathologically proved endometrial carcinoma underwent preoperative T2-weighted fast spin-echo, dynamic T1-weighted fast spin-echo, and postcontrast T1-weighted spin-echo MR imaging with a phased-array surface coil. The uterine long-axis planes in each sequence were reviewed at separate sessions by three radiologists blinded to the histopathologic data. RESULTS: For the diagnosis of myometrial invasion, no statistically significant differences were found among T2-weighted imaging, dynamic imaging, and postcontrast T1-weighted imaging. For the diagnosis of deep myometrial invasion, T2-weighted and dynamic images showed higher specificity than postcontrast T1-weighted images (T2-weighted, 89%; dynamic, 88%; and postcontrast T1-weighted, 80%). For cervical invasion, T2-weighted and dynamic images showed larger areas under receiver operating characteristic curves than did postcontrast T1-weighted images (T2-weighted, 0.78; dynamic, 0.71; and postcontrast T1-weighted, 0.67). CONCLUSION: T2-weighted imaging is useful for identifying the stage of endometrial carcinoma.     

Myocardial perfusion SPET in the detection of coronary artery disease in orthotopic heart transplantation

BACKGROUND: Thallium-201 (201Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced 201Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory. HYPOTHESIS: This study was undertaken to evaluate the efficacy of an early 201Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging. MATERIALS AND METHODS: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of 201Tl were administered, and two further sets of images were acquired 1 h and 4 h later. RESULTS: In each set of images, a total of 496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10 (3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of 201Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis of the 4 h CRI. CONCLUSION: These results indicate that early postexercise reinjection of 201Tl in combination with sublingual nitroglycerin followed by 1 h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.     

Imaging experimental infective endocarditis with indium-111-labeled blood cellular components

The capability of radionuclide imaging to detect experimental aortic valve infective endocarditis was assessed with indium-111 (111In)-labeled blood cells. Sequential cardiac imaging and tissue distribution studies were obtained in 17 rabbits with infective endocarditis after administration of 111In-platelets and in five after 111In-polymorphonuclear leukocytes. Forty-eight to 72 hours after platelet administration, in vivo imaging demonstrated abnormal 111In uptake in all animals in the region of the aortic valve in an anatomically distinct pattern. Images of the excised heart showed discrete cardiac uptake conforming to the in vivo image and gross pathological examination. 111In platelet uptake in vegetations from the 17 animals averaged 240 +/- 41 times greater than that in normal myocardium and 99 +/- 15 times greater uptake in blood. In contrast, 111In-leukocyte cardiac imaging showed no abnormal aortic valve uptake 24 hours after tracer administration and the lesion myocardium activity ratio was only 5 +/- 2 (3 +/- 1 for lesion/blood activity). Four normal rabbits demonstrated neither positive 111In platelet scintigraphs nor abnormal cardiac tissue uptake. Likewise, noncellular 111In was not concentrated to any significant extent in three animals with infective endocarditis. This study demonstrates that 111In platelet, but not leukocyte cardiac imaging, is a sensitive technique for detecting experimental infective endocarditis. The imaging data conform to the cellular pathology of the infective endocarditis vegetation.     

Hepatic cavernous hemangioma: appearance on T2-weighted fast spin-echo MR imaging with and without fat suppression

OBJECTIVE: The goals of our study were to define the morphologic appearance of cavernous hemangioma of the liver on T2-weighted fast spin-echo MR imaging and to determine if the use of fat suppression may quantitatively and qualitatively modify the MR imaging appearance of cavernous hemangioma. SUBJECTS AND METHODS: Twenty-six patients with cavernous hemangiomas of the liver were prospectively studied with T2-weighted MR imaging with a fast spin-echo technique with and without fat suppression. Thirteen patients had known hemangiomas for more than 2 years, with no change in size or morphology during this period. The remaining 13 patients had diagnoses based on dynamic CT and sonography and an absence of change in the morphology and size of their lesions during follow-up of more than 6 months (range, 6-12 months) after the MR imaging studies. Values for signal intensity and contrast-to-noise (C/N) ratios in cavernous hemangiomas that were obtained with and without fat suppression were compared. Images were qualitatively analyzed separately at identical level and window settings by two interpreters for morphologic features of cavernous hemangiomas. RESULTS: No significant difference was found between signal intensity values obtained using the fat-suppressed fast spin-echo MR imaging technique (5.62 +/- 1.14 [SD]) and those obtained without fat suppression (5.51 +/- 1.23). Values for C/N ratios obtained with the fat-suppressed fast spin-echo MR imaging technique (20.13 +/- 7.63) were significantly superior to those obtained without fat suppression (16.59 +/- 5.31) (p < .001). On T2-weighted fast spin-echo MR imaging without fat suppression, 100% of cavernous hemangiomas were hyperintense relative to the spleen, 90% had well-defined and sharp margins, 55% were isointense to CSF, and 76% were homogeneous. Without fat suppression, 34% of cavernous hemangiomas showed the combination of isointensity to CSF, well-defined margins, and homogeneity. On T2-weighted fast spin-echo MR imaging with fat suppression, all cavernous hemangiomas showed this same combination of features. CONCLUSION: Seventy-six percent of hepatic cavernous hemangiomas were homogeneous on T2-weighted fast spin-echo MR imaging, and 55% were isointense to CSF. However, only 34% of hepatic cavernous hemangiomas showed typical features. Although fat suppression significantly increased the C/N ratio of cavernous hemangiomas of the liver, fat suppression did not affect their morphologic appearance on T2-weighted fast spin-echo MR imaging.     

Sonographic findings of rotator cuff tears: correlation with MR imaging

Sonography was performed in 41 patients with symptoms referable to the rotator cuff. Sonography was performed immediately after MR imaging, so that the information obtained by MR imaging could be applied to sonographic diagnosis. Twenty patients were diagnosed from T2-weighted images as having complete tears of the rotator cuff. Sonography showed full-thickness anechoic areas in 12 of the 20 patients, heterogeneous hyperechoic areas in seven, and no abnormal findings in the other one. Thirteen patients were diagnosed as having incomplete tears with MR imaging. Sonography showed heterogeneous hyperechoic areas in 12, but no abnormal findings in one of the 13. Hyperechoic areas in the rotator cuff were shown in four of eight patients who had been diagnosed from T2-weighted images as not having tears. We consider full-thickness anechoic areas to be specific findings of complete tears, although some patients with rotator cuff tears did not show this finding.     

Contrast-enhanced magnetic resonance imaging of the coronary arteries. A review

The advent and continued improvement of T1-shortening contrast media have revolutionized magnetic resonance angiography (MRA) of the entire body in recent years. The technical basis for contrast-enhanced MRA is fast three-dimensional (3D) imaging. A brief historic review of the technical advances in MR coronary artery imaging clearly points to the importance of improved gradient capabilities that led to the development and wide application of fast 3D imaging. The use of contrast agents in coronary artery imaging has been expected for many years, given its success in other parts of the body. Nevertheless, because of the potential difficulties and unique characteristics of fast 3D imaging in the heart, the utility of contrast agents in coronary artery imaging has been systematically investigated only in the last 2 years. Initial experience from our group and others showed that contrast agents have great potential in pushing MR coronary artery imaging to a much higher level in terms of speed and signal-to-noise ratio (SNR), and intravascular agents are more desirable than extracellular agents. Nevertheless, because of the technical challenges and the diversity of methods used for coronary artery imaging, much more effort is needed to continue to improve the imaging techniques and further to define the roles of contrast agents in coronary artery imaging.     

Multiphoton excitation provides optical sections from deeper within scattering specimens than confocal imaging

Multiphoton excitation fluorescence imaging generates an optical section of sample by restricting fluorophore excitation to the plane of focus. High photon densities, achieved only in the focal volume of the objective, are sufficient to excite the fluorescent probe molecules by density-dependent, multiphoton excitation processes. We present comparisons of confocal with multiphoton excitation imaging of identical optical sections within a sample. These side-by-side comparisons of imaging modes demonstrate a significant advantage of multiphoton imaging; data can be obtained from deeper within biological specimens. Observations on a variety of biological samples showed that in all cases there was at least a twofold improvement in the imaging penetration depth obtained with multiphoton excitation relative to confocal imaging. The more pronounced degradation in image contrast deep within a confocally imaged sample is primarily due to scattered emission photons, which reduce the signal and increase the local background as measurements of point spread functions indicated that resolution does not significantly change with increasing depth for either mode of microscopy. Multiphoton imaging does not suffer from degradation of signal-to-background to nearly the same extent as confocal imaging because this method is insensitive to scatter of the emitted signal. Direct detection of emitted photons using an external photodetector mounted close to the objective (possible only in a multiphoton imaging system) improves system sensitivity and the utilization of scattered emission photons for imaging. We demonstrate that this technique provides yet further improvements in the capability of multiphoton excitation imaging to produce good quality images from deeper within tissue relative to confocal imaging.     

Pulmonary thromboendarterectomy: an advance in the treatment of chronic thromboembolic pulmonary hypertension

99mTc-tetrofosmin myocardial imaging was performed in a 62-year-old woman who had undergone standard radical mastectomy for right breast cancer 6 years ago. Although the result was negative for the ischemic heart disease, it showed abnormal accumulation corresponding to the bone metastases in the spine. We believe that 99mTc-tetrofosmin imaging is helpful in detecting bone metastases from breast cancer.