Lésion vertébrale froide en TEP/TDM au FNa-(18F) : n’oubliez pas l’ostéonécrose vertébrale (ou maladie de Kümmell) !

A 75-year-old woman presented with a history of severe backache and spinal cord compression syndrome. MRI revealed a well-circumscribed, homogeneous, wedge-shaped lesion involving T11 vertebral body, which was hypointense on T1- and hyperintense on T2-weighted images with bulging posterior border. Patient benefited from a decompressive T10–T12 laminectomy. Four months later, a new vertebral collapse of T10 was evidenced on plain X-rays. A second MRI exam displayed worrisome diffuse signal abnormalities of T10 pointing to a space-occupying lesion. A (18F)-NaF PET/CT was ordered and disclosed an hypometabolic (“cold”) activity of T10 and T11 vertebral bodies with a partial postero-lateral hypermetabolic rim. Twined low dose CT evidenced fracture sequelae and air-filled cleft within vertebral bodies. Histopathologic examination of the biopsy specimen of T10 revealed thinned out trabeculae surrounded by hyalinized fatty marrow cells and fibrovascular tissue, thus ascertaining the diagnosis of avascular necrosis of the vertebra. The radiographic and CT sine qua non for Kümmell's disease is intraosseous vacuum phenomenon. That is to say, vacuum clefts (VCs) of the vertebral bodies are radiographically recognized as a vacuum or air-filled cleft within the collapsed vertebrae. This sign is felt to be suggestive of ischemic necrosis but not specific as VCs of the vertebral bodies have also been associated with delayed union or non-union of osteoporotic fractures. Because of often misleading MRI abnormalities, integrative interpretation of (18F)-NaF PET/CT pattern should be undertaken in order to suspect Kümmell's disease and to discard some of the differentials.     

Radiologic follow-up and prognosis of efficiency of systemic Sr-89 Cl-2 therapy of bone metastases in prostate cancer

We evaluated possibilities of bone scintigraphy with 99mTc-methylendiphosphonate (99mTc-MDP) and magnetic resonance imaging (MRI) in follow-up and prediction of effect in patients with extensive bone metastatic disease treated with betha-emitter 89SrCl2. 24 patients with prostate cancer and extensive metastatic involvement of skeleton were referred for the study. 89SrCl2 was injected as single injection of 150 MBq (4 mCi), in eighteen from Amersham plc., England, as Metastron, in six--from Medradiopreparat, Russia). In all patients bone scintigraphy with 99mTc-MDP and MRI study of metastatic regions were performed before and in 3 months after 89SrCl2 injection. Patients treated with Metsatron were also studied in 6 months after injection. Quantitative analysis of data comprised count and anatomic dimensions of metastatic areas and calculation of indices [metastasis/intact bone] both for scintillation count of 99mTc-MDP bone scans and signal intensity of T1-weighted MRI scan. Henceforth, we conclude the data of bone scanning with 99mTc-MDP and of MRI give evidencies for significant regress of bone metastases in patients treated with 89SrCl2 besides symptomatic suppression of pain syndrome. 99mTc-MDP bone scanning is also of predictive value for the prognosis of therapeutic effect of systemic radiotherapy with 89SrCl2 in prostate cancer.     

Noninvasive magnetic resonance imaging of the development of individual colon cancer tumors in rat liver

Monitoring tumor development is essential for the understanding of mechanisms involved in tumor progression and to determine efficacy of therapy. One of the evolving approaches is longitudinal noninvasive magnetic resonance imaging (MRI) of tumors in experimental models. We applied high-resolution MRI at 7 Tesla to study the development of colon cancer tumors in rat liver. MRI acquisition was triggered to the respiratory cycle to minimize motion artifacts. A special radio frequency (RF) coil was designed to acquire detailed T1-weighted and T2-weighted images of the liver. T2-weighted images identified hyperintense lesions representing tumors with a minimum diameter of 2 mm, enabling the determination of growth rates and morphological aspects of individual tumors. It is concluded that high-resolution MRI using a dedicated RF coil and triggering to the respiratory cycle is an excellent tool for quantitative and morphological analysis of individual diffusely distributed tumors throughout the liver. However, at present, MRI requires expensive equipment and expertise and is a time-consuming methodology. Therefore, it should preferably be used for dedicated applications rather than for high-throughput assessment of total tumor load in animals.     

Functional Dynamic Contrast-Enhanced Magnetic Resonance Imaging in an Animal Model of Brain Metastases: A Pilot Study

Background

Brain metastasis is a common disease with a poor prognosis. The purpose of this study is to test feasibility and safety of the animal models for brain metastases and to use dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to enhance detection of brain metastases.

Methods

With approval from the institutional animal ethics committee, 18 New Zealand rabbits were randomly divided into three groups: Group A received an intra-carotid infusion (ICI) of mannitol followed by VX2 cells; group B received successive ICI of mannitol and heparin followed by VX2 cells; and group C received an ICI of normal saline. The survival rate and clinical symptoms were recorded after inoculation. After two weeks, conventional MRI and DCE-MRI were performed using 3.0 Tesla scanner. The number of tumors and detection rate were analyzed. After MRI measurements, the tumors were stained with hematoxylin-eosin.

Results

No rabbits died during the procedure. The rabbits had common symptoms, including loss of appetite, lassitude and lethargy, etc. at 10.8±1.8 days and 8.4±1.5 days post-inoculation in group A and B, respectively. Each animal in groups A and B re-gained the lost weight within 14 days. Brain metastases could be detected by MRI at 14 days post-inoculation in both groups A and B, with metastases manifesting as nodules in the brain parenchyma and thickening in the meninges. DCE-MRI increased the total detection of tumors compared to non-contrast MRI (P<0.05). The detection rates of T1-weighted image, T2-weighted image and DCE-MRI were 12%, 32% and 100%, respectively (P<0.05). Necropsy revealed nodules or thickening meninges in the gross samples and VX2 tumor cytomorphologic features in the slides, which were consistent with the MRI results.

Conclusions

The VX2 rabbit model of brain metastases is feasible, as verified by MRI and pathologic findings, and may be a suitable platform for future studies of brain metastases. Functional DCE-MRI can be used to evaluate brain metastases in a rabbit model.     

Biomechanics of vertebral level, geometry, and transcortical tumors in the metastatic spine

Metastatic involvement can disrupt the mechanical integrity of the spine, rendering vertebrae susceptible to burst fracture and neurologic damage. Fracture risk assessment for patients with spinal metastases is important in considering prophylactic treatment options. Stability of thoracic vertebrae affected by metastatic disease has been shown to be dependent on tumor size and bone density, but additional structural and geometric factors may also play a role in fracture risk assessment. The objective of this study was to use parametric finite element modeling to determine the effects of vertebral level, geometry, and metastatic compromise to the cortical shell on the risk of burst fracture in the thoracic spine. Analysis of vertebral level and geometry was assessed by investigation of seven scenarios ranging in geometry from T2-T4 to T10-T12. The effects of cortical shell compromised were assessed by comparison of four transcortical scenarios to a fully contained central vertebral body tumor scenario. Results demonstrated that upper thoracic vertebrae are at greater risk of burst fracture and that kyphotic motion segments are at decreased risk of burst fracture. Vertebrae with transcortical lesions are up to 30% less likely to lead to burst fracture initiation. The findings of this study are important for improving the understanding of burst fracture mechanics in metastatically involved vertebrae and guiding future modeling efforts.     

Imaging of interstitial cryotherapy--an in vitro comparison of ultrasound, computed tomography, and magnetic resonance imaging.

RATIONALE AND OBJECTIVES: To evaluate the imaging capabilities of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) in monitoring interstitial cryotherapy and to compare them with visual control. METHODS: An experimental MR-compatible, vacuum-insulated and liquid nitrogen-cooled cryoprobe was inserted under in vitro conditions into a porcine liver, which was kept at a temperature of 37 +/- 1 degrees C, in a water bath with continuous stirring. The freezing procedure was controlled macroscopically, by US (Toshiba Sonolayer, 7.5-MHz linear array transducer), by CT (Siemens Somatom Plus, slice thickness 2-8 mm, 165-210 mA at 120 kV), and by MRI (Philips Gyroscan ACS-NT, FFE TR/TE/FA = 15/5.4/25 degrees, T1-SE 550/20, T2-TSE 1800/100) after the iceball reached its maximum size. RESULTS: The maximum iceball diameter around the probe tip was 12.0 mm by visual control, 12.4 mm by US, 12.7 mm by CT, and within 12.8 mm by spin echo sequences and 11 mm by gradient echo sequence. Due to the nearly signal-free appearance of the frozen tissue on MR images, the ice/tissue contrast on T1-weighted and gradient echo images was superior to T2-weighted images and CT images. Sonographically, the ice formation appeared as a hyperechoic sickle with nearly complete acoustic shadowing. CONCLUSION: Due to the better ice/tissue contrast, T1-weighted or gradient echo MR images were superior to CT and US in monitoring interstitial cryotherapy. Gradient echo sequences generally underestimated the ice diameter by 15%.     

Radiologic diagnosis of bone metastases recurrence in patients with prostate cancer treated strontium-89

Aiming to evaluate efficiency of 89SrCl (Metastron) in patients with metastatic lesion of the skeleton in prostate cancer we have performed a follow-up scintigraphy of the skeleton with 99mTc-methylendiphosphonate (MDP) and MRI with quantitative study of metastatic foci. 12 patients with prostate cancer (on the average 11 +/- 6 bone metastases were examined using scintigraphy of the skeleton with 99mTc-MDP and MRI study in T1, T2 and proton density modes. Investigations were performed before injected as a single dose of 150 MBq (4 mCi). At all the stages there was made a quantitative study of foci of pathological uptake of 99mTc-MDP compromising numbers of foci, focus parameters, intensity of 99mTc-MDP accumulation in the pathological part relatively the contralateral region as well as quantification of MRI signals from metastatic areas in signal intensity units. In 3 month 4 patients with extensive metastatic skeletal lesion (> 12) showed a considerable decrease of number of foci of pathological 99mTc-MDP uptake (on average to 6 +/- 3). In the remained metastatic foci there was noted a decrease of dimensions and 99mTc-MDP uptake intensity at an average by 29.8 +/- 15%, improvement in T1 intensity by 113 +/- 55.6 units. In 2 patients who initially presented a "superscan" pattern on 99mTc-MDP bone scintigraphy the 89SrCl treatment converted this of low intensity had demonstrated their complete regression. Results of radiologic follow-up of bone metastases in prostate cancer using MRI and bone scintigraphy with 99mTc-MDP argue that systemic radiotherapy with 89SrCl induces significant regress of metastatic process that involves all volume of the metastases.     

Magnetic resonance imaging changes of sacroiliac joints in patients with recent-onset inflammatory back pain: inter-reader reliability and prevalence of abnormalities

To study the inter-reader reliability of detecting abnormalities of sacroiliac (SI) joints in patients with recent-onset inflammatory back pain by magnetic resonance imaging (MRI), and to study the prevalence of inflammation and structural changes at various sites of the SI joints. Sixty-eight patients with inflammatory back pain (at least four of the five following criteria: symptom onset before age 40, insidious onset, morning stiffness, duration >3 months, improvement with exercise--or three out of five of these plus night pain) were included (38% male; mean age, 34.9 years [standard deviation 10.3]; 46% HLA-B27-positive; mean symptom duration, 18 months), with symptom duration <2 years. A MRI scan of the SI joints was made in the coronal plane with the following sequences: T1-weighted spin echo, short-tau inversion recovery, T2-weighted fast-spin echo with fat saturation, and T1-spin echo with fat saturation after the administration of gadolinium. Both SI joints were scored for inflammation (separately for subchondral bone and bone marrow, joint space, joint capsule, ligaments) as well as for structural changes (erosions, sclerosis, ankylosis), by two observers independently. Agreement between the two readers was analysed by concordance and discordance rates and by kappa statistics. Inflammation was present in 32 SI joints of 22 patients, most frequently located in bone marrow and/or subchondral bone (29 joints in 21 patients). Readers agreed on the presence of inflammation in 85% of the cases in the right SI joint and in 78% of the cases in the left SI joint. Structural changes on MRI were present in 11 patients. Ten of these 11 patients also showed signs of inflammation. Agreement on the presence or absence of inflammation and structural changes of SI joints by MRI was acceptable, and was sufficiently high to be useful in ascertaining inflammatory and structural changes due to sacroiliitis. About one-third of patients with recent-onset inflammatory back pain show inflammation, and about one-sixth show structural changes in at least one SI joint.     

MRI of the pelvis in comparison with CT scan

This study gives results of magnetic resonance imaging (MRI) in the evaluation of male (23 cases) and female (29 cases) pelvis. Thirty nine patients with abnormal pelvis were compared with CT and ultrasounds. MRI and CT have proven equally sensitive to the presence of disease, with a better visualization of calcified tumours or benign lesions with CT, and a superior display of soft tissue spreads and bone metastases with MRI. The signal characteristics from various uterine, bladder and ovarian tumours show an overlap. The same phenomenon is observed between benign and malignant prostatic hypertrophy. The best sequences for pelvic study are, in our experience, IR or short TR spin-echo for T1-weighted images, and spin-echo with 1200 TR for T2 images. Calculated T1 and T2 maps may improve MRI results.     

Correlation of histopathological findings and magnetic resonance imaging in the spine of patients with ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease which affects primarily the sacroiliac joints and the spine. In patients with active disease, magnetic resonance imaging (MRI) of the spine shows areas of bone marrow edema, the histopathological equivalent of which is unknown. In this study we correlate inflammation in the spine of patients with AS as revealed by histological examination with bone marrow edema as detected by MRI. We have compared the histopathological findings of zygapophyseal joints from 8 patients with AS (age: 30 to 64, disease duration 7 to 33 years) undergoing spinal surgery with findings in MRI. For histopathological analysis, we quantified infiltrates of CD3+, CD4+ and CD8+ T cells as well as CD20+ B cells immunohistochemically. Bone marrow edema was evaluated in hematoxylin and eosin stained sections and quantified as the percentage of the bone marrow area involved. All patients with AS showed interstitial mononuclear cell infiltrates and various degrees of bone marrow edema (range from 10% to 60%) in histopathological analysis. However, in only three of eight patients histopathological inflammation and edema in the zygapophyseal joints correlated with bone marrow edema in zygapophyseal joints of the lumbar spine as detected by MRI. Interestingly, two of these patients showed the highest histological score for bone marrow edema (60%). This first study correlating histopathological changes in the spine of patients with AS with findings in MRI scans suggests that a substantial degree of bone marrow inflammation and edema is necessary to be detected by MRI.     

Distribution Features of Skeletal Metastases: A Comparative Study between Pulmonary and Prostate Cancers

Bone scintigraphies are widely applied for detecting bone metastases. The aim of this study was to investigate distribution features of bone metastases in pulmonary and prostate cancers. Bone scintigraphies were performed in 460 patients with pulmonary cancer and 144 patients with prostate cancer. Patients were divided into three groups according to the total number of bone metastases: few bone metastases, moderate bone metastases, and extensive bone metastases. We compared the distribution of bone metastases in the two cancers, and analyzed the relationship between the distribution of metastatic lesions and their metastatic patterns. A total of 2279 and 2000 lesions of bone metastases were detected in 258 patients with pulmonary cancer and 102 patients with prostate cancer, respectively. In patients with few bone metastases, the distributions of metastatic lesions in the vertebrae (χ² = 16.0, P = 0.000) and thoracic bones (χ² = 20.7, P = 0.002) were significantly different between pulmonary and prostate cancers. In cases with moderate bone metastases, the distributions in the vertebrae (χ² = 6.6, P = 0.010), pelvis (χ² = 15.1 P = 0.000), and thoracic bones (χ² = 38.8, P = 0.000) were also significantly different between the two cancers. However, in patients with extensive bone metastases, the distributions were very similar. As the total number of bone metastases increased, their distribution in pulmonary cancer did not noticeably change, but the distribution in the vertebrae and thoracic bones of prostate cancer patients significantly changed. Accordingly, the distribution characteristics of bone metastases differed in pulmonary and prostate cancers, mainly in the early stages of metastasis.     

Multimodality imaging of endothelial progenitor cells with a novel multifunctional probe featuring positive magnetic resonance contrast and near-infrared fluorescence

The multimodal strategy incorporating T1-weighted magnetic resonance imaging (MRI) and near-infrared (NIR) fluorescence imaging can complement their strengths to provide images with high sensitivity and spatial resolution for noninvasively and dynamically monitoring endothelial progenitor cells (EPCs) in potential EPC-dominated therapies. Here we report the development of a protein-based imaging probe, bCD-PLL-Cy5.5 Conjugate 1, in which the bacterial cytosine deaminase (bCD) protein was modified with poly-l-lysine (PLL) that is labeled with imaging reporters, including T1-weighted MRI contrast chelator and NIR fluorophore. Conjugate 1 showed low cytotoxicity in EPCs isolated from the rabbit peripheral blood. The normalized cell viability was maintained above 90% after incubation for 1 to 5 days. Fluorescence microscopy of live cells indicated rapid cellular uptake of Conjugate 1 into EPCs in 15 minutes, and flow cytometry studies demonstrated the time-dependent internalization of Conjugate 1 with maximum uptake 48 hours after the treatment. MRI of phantoms demonstrated significant reduction of the T1 value of the EPC pellet that was pretreated with 2 μM of Conjugate 1 for 24 hours. Our preliminary data suggest that as a multimodal imaging contrast medium, Conjugate 1 offers a promising imaging probe for tracking the delivery and therapeutic response of EPCs in vivo.     

Optimization of the balanced steady state free precession (bSSFP) pulse sequence for magnetic resonance imaging of the mouse prostate at 3T

Introduction

MRI can be used to non-invasively monitor tumour growth and response to treatment in mouse models of prostate cancer, particularly for longitudinal studies of orthotopically-implanted models. We have optimized the balanced steady-state free precession (bSSFP) pulse sequence for mouse prostate imaging.

Methods

Phase cycling, excitations, flip angle and receiver bandwidth parameters were optimized for signal to noise ratio and contrast to noise ratio of the prostate. The optimized bSSFP sequence was compared to T1- and T2-weighted spin echo sequences.

Results

SNR and CNR increased with flip angle. As bandwidth increased, SNR, CNR and artifacts such as chemical shift decreased. The final optimized sequence was 4 PC, 2 NEX, FA 50°, BW ±62.5 kHz and took 14–26 minutes with 200 µm isotropic resolution. The SNR efficiency of the bSSFP images was higher than for T1WSE and T2WSE. CNR was highest for T1WSE, followed closely by bSSFP, with the T2WSE having the lowest CNR. With the bSSFP images the whole body and organs of interest including renal, iliac, inguinal and popliteal lymph nodes were visible.

Conclusion

We were able to obtain fast, high-resolution, high CNR images of the healthy mouse prostate with an optimized bSSFP sequence.     

Magnetic Resonance Evaluation of Multiple Myeloma at 3.0 Tesla: How Do Bone Marrow Plasma Cell Percentage and Selection of Protocols Affect Lesion Conspicuity?

Purpose

To compare various pulse sequences in terms of percent contrast and contrast-to-noise ratio (CNR) for detection of focal multiple myeloma lesions and to assess the dependence of lesion conspicuity on the bone marrow plasma cell percent (BMPC%).

Materials and Methods

Sagittal T₁-weighted FSE, fat-suppressed T₂-weighted FSE (FS- T₂ FSE), fast STIR and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging of the lumbar spine were performed (n = 45). Bone marrow (BM)-focal myeloma lesion percent contrast and CNR were calculated. Spearman rank correlation coefficients were obtained between percent contrast, CNR and BMPC%. Percent contrasts and CNRs were compared among the three imaging sequences.

Results

BM-focal lesion percent contrasts, CNRs and BMPC% showed significant negative correlations in the three fat-suppression techniques. Percent contrast and CNRs were significantly higher for FS- T2 FSE than for STIR (P<0.01, P<0.05, respectively), but no significant differences were found among the three fat-suppression methods in the low tumor load BM group.

Conclusion

The higher BMPC% was within BM, the less conspicuous the focal lesion was on fat-suppressed MRI. The most effective protocol for detecting focal lesions was FS- T₂ FSE. In the high tumor load BM group, no significant differences in lesion conspicuity were identified among the three fat-suppression techniques.     

Role of Diffusion Weighted Imaging and Contrast-Enhanced MRI in the Evaluation of Intrapelvic Recurrence of Gynecological Malignant Tumor

Background and Purpose

To investigate the diagnostic performance of diffusion-weighted imaging (DWI) and contrast-enhanced imaging in combination with T2-weighted imaging (T2WI) for magnetic resonance imaging (MRI) evaluation of intrapelvic recurrence of gynecological malignancies.

Materials and Methods

Sixty-two patients with suspected intrapelvic recurrence of gynecological malignancies underwent pelvic MRI including T2WI DWI, and contrast-enhanced imaging. Diagnostic performance for detection of local recurrence, pelvic lymph node and bone metastases, and peritoneal lesions was evaluated by consensus reading of two experienced radiologists using a 5-point scoring system, and compared among T2WI with unenhanced T1-weighted imaging (T1WI) (protocol A), a combination of protocol A and DWI (protocol B), and a combination of protocol B and contrast-enhanced imaging (protocol C). Final diagnoses were obtained by histopathological examinations, radiological imaging and clinical follow-up for at least 6 months. Receiver operating characteristic (ROC) analysis and McNemar test were employed for statistical analysis.

Results

Locally recurrent disease, lymph node recurrence, peritoneal dissemination and bone metastases were present in 48.4%, 29.0%, 16.1%, and 6.5% of the patients, respectively. The patient-based sensitivity, specificity, accuracy, and area under the ROC curve (AUC) for detection of intrapelvic recurrence were 55.0, 81.8, 64.5% and 0.753 for protocol A, 80.0, 77.3, 79.0% and 0.838 for protocol B, and 80.0, 90.9, 83.9% and 0.862 for protocol C, respectively. The sensitivity, accuracy, and AUC were significantly better for protocols B and C than for protocol A (p<0.001). There was no significant difference between protocols B and C.

Conclusion

MRI using a combination of DWI and T2WI gives comparatively acceptable results for assessment of intrapelvic recurrence of gynecological malignancies.     

Comparison of Dixon Sequences for Estimation of Percent Breast Fibroglandular Tissue

Objectives

To evaluate sources of error in the Magnetic Resonance Imaging (MRI) measurement of percent fibroglandular tissue (%FGT) using two-point Dixon sequences for fat-water separation.

Methods

Ten female volunteers (median age: 31 yrs, range: 23–50 yrs) gave informed consent following Research Ethics Committee approval. Each volunteer was scanned twice following repositioning to enable an estimation of measurement repeatability from high-resolution gradient-echo (GRE) proton-density (PD)-weighted Dixon sequences. Differences in measures of %FGT attributable to resolution, T₁ weighting and sequence type were assessed by comparison of this Dixon sequence with low-resolution GRE PD-weighted Dixon data, and against gradient-echo (GRE) or spin-echo (SE) based T₁-weighted Dixon datasets, respectively.

Results

%FGT measurement from high-resolution PD-weighted Dixon sequences had a coefficient of repeatability of ±4.3%. There was no significant difference in %FGT between high-resolution and low-resolution PD-weighted data. Values of %FGT from GRE and SE T₁-weighted data were strongly correlated with that derived from PD-weighted data (r = 0.995 and 0.96, respectively). However, both sequences exhibited higher mean %FGT by 2.9% (p < 0.0001) and 12.6% (p < 0.0001), respectively, in comparison with PD-weighted data; the increase in %FGT from the SE T₁-weighted sequence was significantly larger at lower breast densities.

Conclusion

Although measurement of %FGT at low resolution is feasible, T₁ weighting and sequence type impact on the accuracy of Dixon-based %FGT measurements; Dixon MRI protocols for %FGT measurement should be carefully considered, particularly for longitudinal or multi-centre studies.     

Using magnetic resonance imaging to identify the lumbosacral segment in children

Identification of the lumbosacral (L-S) segment on magnetic resonance (MR) images is important for appropriate treatment of disease in the lumbosacral (L-S) area. In the study, data obtained from plain A-P radiographs of the L-S spine and sagittal MR imaging scans (sagittal T1- and T2-weighted sequences) of the L-S spine and sacrum with the coccygeal bone, are analyzed. Twenty-six children aged 10 to 14 years were examined for back pain. On the standard A-P radiographs of the L-S spine, a L-S transitional vertebra as classified according to the method of Castellvi et al. was found in 17 subjects. The problem arose as to whether this was lumbalisation or sacralisation, and how to determine which vertebra was L5 wich S1. On the sagittal MR imaging studies the same question applied. A need emerged for a simple method which would identify the L-S segment on the sagittal MR imaging studies of the L-S spine in children so that in case of a tumor, inflammation, spondilolystesis, or protrusion of a disc, the level in the L-S spine where the problem is localized can be accurately identified. To this objective we selected the method using detection of the S1 vertebra. This involved that, in addition to the sagittal MR imaging scans of the L-S spine, sagittal images of the sacrum and coccygeal bone be also obtained. on the T2-weighted sequence, the sacrum can be clearly distinquished from the coccygeal bone. By counting from the S5 up, the S1 vertebra can be accurately identified. Determination of the S1 vertebra enables detection of the L5 vertebra and, in turn, of all other lumbar vertebrae. In patients in whom a T2-weighted MR studies were done S1 could be precisely determined and so could the L5 vertebra. In this process, whether the patient had a transitional vertebra or whether there was lumbarisation or sacralisation was irrelevant.     

Some physiological and developmental considerations of the temperature-gradient hypothesis of bone marrow distribution

In adult humans, active bone marrow is confined to the proximal portion of the skeleton. Huggins and Blocksom (J. Exp. Med., 64: 253, '36) concluded that a high temperature is needed for hematopoiesis in rats. However, precise thermal regulation of human marrow was not found (Petrakis, J. Appl. Physiol., 4: 549, '52). Because these experiments made on the rat tail are the basis for a commonly accepted hypothesis attempting to explain marrow distribution in man, it was considered of importance to re-examine the caudal vertebra model upon which the temperature-gradient hypothesis is based. The sacral and coccygeal vertebrae were examined in rats, mice and humans with respect to marrow cellularity and temperature. In rats and mice and man it was observed that the transition between hematopoietically-active and inactive (fatty) vertebral marrow cavities is abrupt, occurring at the level of the first and second caudal and coccygeal vertebrae. All vertebrae distal to this point have fatty marrow. Of significance was the finding that the vertebral and coccygeal temperatures, as measured with a thermister needle, remain unaltered over this area of changing cellular activity. These anatomical and thermal observations of the caudal vertebrae of rats, mice, and humans indicate that the use of the tail as an experimental model does not support the hypothesis that temperature is a primary factor in the physiological maintenance of hematopoiesis in bone marrow. The possible relationship of hematopoietic activity to developmental and other factors peculiar to the caudal vertebra model is under study.     

Oesophageal carcinoma demonstrated by whole-body nuclear magnetic resonance imaging.

The quality of the images produced by nuclear magnetic resonance (NMR) imaging has steadily improved over the past five years. Images of the head, thorax, and abdomen have clearly shown the normal anatomy. A clinical trial of NMR imaging has therefore been started in Aberdeen to assess its diagnostic accuracy and compare it with conventional radiography and other imaging technique. The first patient examined by whole-body NMR imaging had carcinoma of the oesophagus diagnosed on barium meal examination. A technetium-99m-sulphur colloid liver scan also showed hepatic metastases. NMR imaging showed a large tumour in the lower third of the oesophagus, and areas of increased proton spin-lattice relaxation time (T1) on a section through the liver corresponded with the metastases shown on the radionuclide scan. Increased areas of T1 were present in some vertebrae, and a technetium-99m bone scan confirmed the presence of bone metastases. The NMR images in this patient compared well with the images from other techniques. The continuing clinical trial may show that NMR is an accurate diagnostic aid which will complement existing techniques for diagnosing intrathoracic and intra-abdominal conditions.