Tissue characterization and assessment of preoperative chemotherapeutic response in musculoskeletal tumors by in vivo 31P magnetic resonance spectroscopy.

This study investigates the potential of in vivo 31P magnetic resonance spectroscopy (MRS) to characterize musculoskeletal tumors and to determine preoperative levels of histological necrosis, which is an important clinical indicator of patient response. Pretherapy MRS was performed on 28 patients with large musculoskeletal tumors: 13 with osteosarcoma, 3 with chondrosarcoma, 5 with malignant fibrous histiocytoma, 1 with desmoid tumor, 1 with Ewing's, 2 with hemangioendothelioma, 1 with myxoid liposarcoma, 1 with synovial cell sarcoma, and 1 with rhabdomyosarcoma. Fifteen patients had follow-up MRS examinations after commencement of chemotherapy (mean of five/patient), eight of whom have now had surgery. Elevated levels of PMEs (P < 0.01), P(i) (P < 0.01), and PDEs (P < 0.02) as well as elevated tumor pH (P < 0.05) were observed in all patients. The synovial cell sarcoma was characterized by high levels of PMEs (> 20%) and low pH (pH 6.76). This contrasted with the spectra obtained from the malignant fibrous histiocytomas which had high levels of PDEs (17 +/- 5%). Reductions in PDE levels postchemotherapy were associated with a high degree of necrosis (> 90%) at surgery, while an increase in PDE levels was associated with a low level of histological necrosis. Likewise, reductions in the ratios PDE/NTP and PDE/PCr and an increase in P(i)/PDE were also associated with a high level of necrosis.

31P MRS as an early prognostic indicator of patient response to chemotherapy.

In this study 31P spectral changes were closely monitored following the initial administration of cytotoxic drugs and related to five parameters of patient response. Pre- and postchemotherapy 31P MRS examinations were performed on 16 patients with large, malignant tumors. These included four tumor types: (i) lymphoma (n = 7), (ii) breast carcinoma (n = 4), (iii) musculoskeletal tumors (n = 4), and (iv) adenocarcinoma (n = 1). A mean of 5 spectra/patient (range 2-10) was performed following the initial chemotherapy. The spectral trends exhibited by 14 of 16 patients reached "points of maximum change," after which they began to revert toward prechemotherapy values. In 2 of 16 patients that did not respond to the initial chemotherapy regimen, no spectral trends were observed. The degree of change of certain spectral parameters, namely, decreases in PME, PME/PDE, PME/PCr, PME/NTP, PDE/PCr, and tumor pH, as well as increases in the ratios Pi/PME and Pi/PDE, were associated with good patient response and separated responders from nonresponders. Pi/PME appears the most promising for discriminating partial from complete responders.

In vivo phosphorus-31 magnetic resonance spectroscopy of normal and pathological breast tissues.

In vivo phosphorus-31 magnetic resonance spectroscopy, at 1.5 T, in addition to magnetic resonance imaging and mammography, was performed on the breast tissue of 59 subjects, using a 40 mm or 80 mm surface coil for spectral localization. The patients were divided into three groups: Group 1, 46 control subjects; Group 2, nine patients with breast carcinoma; Group 3, four patients with benign breast disease. The relationship of age, menopausal status, breast size and pattern, use of contraceptive pill and history of breast disease to spectral characteristics of breast tissue was examined for the control group. In multivariate analysis, only menopausal status and age were found to be significantly related to tissue biochemistry. Pre-menopausal women had reduced phosphocreatine (PCr) (%) (p = 0.02), and increased phosphomonoesters (PMEs) and beta-nucleotide triphosphate (beta-NTP) (%) (p = 0.05), while the fat-to-water ratio was higher in older women (p = 0.02). No significant differences were identified between the control subjects and the patients with benign breast disease. When spectra from patients with breast carcinoma were compared with an age-matched volunteer group, alpha- and gamma-NTP (%) were found to be higher in the cancer tissue (p less than 0.01 and p = 0.01, respectively), while PCr (%) was reduced (p less than 0.01). The ratio beta-NTP:PCr was higher in the carcinoma group of patients (p less than 0.05). In vivo phosphorus-31 magnetic resonance spectroscopy is a non-invasive examination which may prove useful in the early differentiation of malignant breast disease from normal and benign conditions.

The role of discography in lumbar disc disease: a comparative study of magnetic resonance imaging and discography.

This study reviews prospectively a series of 29 patients who were examined by magnetic resonance imaging (MRI) and discography for degenerative disc disease. All had persistent low-back pain and non-diagnostic initial investigations, including plain films, myelography and/or computed tomography (CT). The imaging characteristics for degenerative disc disease correlated in 65 out of 73 intervertebral levels. All symptomatic discs were degenerate on both MRI and discography. Features of degenerative disc disease on MRI were assessed retrospectively, with a view to identifying the symptomatic level as defined by discography. MRI could not reliably detect this level, particularly in those with multi-level degenerative disc disease. Positive reproduction of symptoms at discography was the criteria used for surgery. All 12 patients in this group had posterior spinal fusion performed. Nine improved and three were unchanged. Of the ancillary features associated with disc degeneration, only a bulging annulus fibrosis proved to be of any value on MRI. Nonetheless, MRI should be used as the primary investigation in this patient group as it can lead to a marked reduction in the number of disc levels requiring injection.

Breast disease: tissue characterization with Gd-DTPA enhancement profiles.

Magnetic resonance (MR) imaging of the breast is currently of limited value because of lack of specificity. Enhanced MR imaging with gadolinium diethylenetriaminepentaacetic acid (DTPA) has been shown to be helpful in the further characterization of breast tissue. This prospective study attempted to differentiate benign and malignant breast disease with a dynamic enhancement technique. Bolus injection of Gd-DTPA and a short MR imaging time were used to examine 18 patients with a palpable breast mass. Construction of enhancement profiles helped effectively differentiate benign and malignant lesion (P less than .001). Dynamic MR imaging shows promise for the further characterization of breast tissue and, particularly, identification of breast carcinoma.

Osteosarcoma: use of MR imaging and MR spectroscopy in clinical decision making.

Magnetic resonance (MR) imaging was performed on 14 patients with histologically proved osteosarcoma (mean age, 14.4 years). There was excellent correlation of intramedullary tumor extent as determined with MR imaging and pathologic examination (r = 99%). This was facilitated by the presence of a chemical shift artifact at the tumor-marrow interface on the T1-weighted images. The correlation between CT and pathologic findings was not as good (r = 84%). In a single patient, however, a 10-cm length of sclerotic bone was incorrectly interpreted as being tumor. If this case is excluded, the correlation between CT and pathologic findings improves significantly (r = 96%). T2-weighted images were optimal in demonstrating soft-tissue bulk and breach of the epiphysis or cortex. Vascular involvement was also readily defined. The T2 value of the tumor soft-tissue component decreased in patients who were deemed to have responded well to therapy. Two patients with very high T2 values after chemotherapy developed wide-spread metastatic disease and died. Phosphorus-31 MR spectroscopy of five patients with osteosarcoma showed elevated levels of phosphomonoesters (PMEs), inorganic phosphate (Pi), and phosphodiesters (PDEs). PME and PDE peak areas decreased in three patients after chemotherapy, while Pi peak areas increased.