Development of a novel animal model of rotator cuff tear arthropathy replicating clinical features of progressive osteoarthritis with subchondral bone collapse.

Objective: To establish an animal model of modified cuff tear arthropathy (mCTA) in order to better replicate the pathophysiology associated with rotator cuff tear-induced humeral head collapse. Design: mCTA was induced by transection of the rotator cuff, the long head of the biceps brachii (LHB), and superior half of the joint capsule in the right shoulder of 12-week-old rats; the left shoulder underwent sham surgery. The severity of CTA was quantitated using the Murine Shoulder Arthritis Score (MSAS). The trabecular bone of the humeral head and metaphysis was analyzed using bone histomorphometry. The expression of proinflammatory cytokines and catabolic enzymes was evaluated immunohistochemically. Results: In the mCTA model, the MSAS increased starting from 2 weeks after induction, and there was notable subchondral bone collapse with fibrous cells at 4 weeks. The mCTA cartilage exhibited positive staining for TNF-α, IL-1ß/6, MMP-3/13, and ADAMTS5. The trabecular bone volume was reduced not only in the subchondral bone but also in the metaphysis of the humeri, and bone resorption was enhanced in these areas. In the collapsed subchondral bone, both bone formation and resorption were increased. The fibrous cells showed expression of TNF-α, IL-6, and MMP-13, along with specific markers of mesenchymal stem cells. Furthermore, the fibrous cells showed osteoblastic characteristics (RUNX2-positive) and expressed RANKL. Conclusions: The LHB and the capsuloligamentous complex are critical stabilizers of the glenohumeral joint, serving to prevent the advancement of CTA following massive rotator cuff tears. Fibrous cells appear to play a role in the humeral head bone resorption.

Emissivity-compensated radiation thermometry method using a concave mirror.

In this work, a method to simultaneously measure the temperature and emissivity of any specimen, including metals and semiconductor materials, was developed using a concave mirror and a polarized radiometer. The ratio of the enhanced radiance after reflection off the mirror to the original radiance of a specimen allowed for emissivity determination in the range 0.1-0.9, with a variation of 8%. The combined standard uncertainty, uc, of the temperature measurement by the current method is estimated to be 6.0 K at a temperature of 800 K. This was realized via classification of the parameter α into only three categories that were closely related to the surface roughness. Furthermore, it should be emphasized that the polarized spectral radiance measurements were carried out at a zenith angle of 75°, which contributed significantly to the success of this method.

Intratumoural immune cell landscape in germinoma reveals multipotent lineages and exhibits prognostic significance.

AIMS: Alterations in microenvironments are a hallmark of cancer, and these alterations in germinomas are of particular significance. Germinoma, the most common subtype of central nervous system germ cell tumours, often exhibits massive immune cell infiltration intermingled with tumour cells. The role of these immune cells in germinoma, however, remains unknown. METHODS: We investigated the cellular constituents of immune microenvironments and their clinical impacts on prognosis in 100 germinoma cases. RESULTS: Patients with germinomas lower in tumour cell content (i.e. higher immune cell infiltration) had a significantly longer progression-free survival time than those with higher tumour cell contents (P = 0.03). Transcriptome analyses and RNA in-situ hybridization indicated that infiltrating immune cells comprised a wide variety of cell types, including lymphocytes and myelocyte-lineage cells. High expression of CD4 was significantly associated with good prognosis, whereas elevated nitric oxide synthase 2 was associated with poor prognosis. PD1 (PDCD1) was expressed by immune cells present in most germinomas (93.8%), and PD-L1 (CD274) expression was found in tumour cells in the majority of germinomas examined (73.5%). CONCLUSIONS: The collective data strongly suggest that infiltrating immune cells play an important role in predicting treatment response. Further investigation should lead to additional categorization of germinoma to safely reduce treatment intensity depending on tumour/immune cell balance and to develop possible future immunotherapies.

Phase II trial of gefitinib alone without radiation therapy for Japanese patients with brain metastases from EGFR-mutant lung adenocarcinoma.

BACKGROUND: Brain metastases (BM) are a common in patients with lung cancer. Although whole-brain radiation therapy (WBRT) is the standard therapy, it may have a risk of decline in cognitive function of patients. In this study, we evaluated the efficacy of gefitinib alone without radiation therapy for the treatment of patients with BM from lung adenocarcinoma. MATERIALS AND METHODS: Eligible patients had BM from lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutations. Gefitinib was given at 250 mg orally once a day until tumor progression or unacceptable toxicity. RESULTS: Forty-one patients were enrolled. The response rate was 87.8%. No patient experienced grade ≥4 toxicity. The median progression-free survival time was 14.5 months (95% CI, 10.2-18.3 months), and the median overall survival time was 21.9 months (95% CI, 18.5-30.3 months). In compared with L858R, exon 19 deletion was associated with better outcome of patients after treatment with gefitinib in both progression-free (p = 0.003) and overall survival (p = 0.025). CONCLUSION: Favorable response of BM to gefitinib even without irradiation was demonstrated. Exon 19 deletion was both a predictive and prognostic marker of patients with BM treated by gefitinib.

A method of reducing background radiance for emissivity-compensated radiation thermometry of silicon wafers.

We studied the spectral and directional emissivities of silicon wafers using an optical polarization technique. Based on simulation and experimental results, we developed two radiation thermometry methods for silicon wafers: one is based on the polarized emissivity-invariant condition and the other is based on the relationship between the ratio of the p- and s-polarized radiance and the polarized emissivity. These methods can be performed at temperatures above 600 °C and over a wide wavelength range (0.9-4.8 µm), irrespective of the dielectric film thickness and the substrate resistivity, which depends on the dopant concentration. The temperature measurements were estimated to have expanded uncertainties (k = 2) of less than 5 °C. With a view to practically applying these methods, we investigated a method to reduce the intense background radiance produced by high-intensity heating lamps. We found that the background radiance can be greatly reduced by using a radiometer that is sensitive to wavelengths of 4.5 or 4.8 µm and suitable geometrical arrangements of a quartz plate. This opens up the possibility of using the two proposed radiation thermometry methods in practical applications.

Gamma knife surgery for brain metastases: indications for and limitations of a local treatment protocol.

OBJECTIVE: The purpose of this retrospective study was to evaluate results of a local treatment protocol using gamma knife surgery (GKS) for brain metastases without upfront whole brain radiation therapy (WBRT). METHODS: Results for 521 consecutive patients satisfying the following 3 criteria were analysed: 1) a maximum of 3 tumours with a diameter of 25 mm or more; 2) no prior WBRT; 3) no surgically in accessible large (>30 mm) tumours. Large tumours were surgically removed and all smaller lesions were treated by GKS without up front WBRT. New lesions, detected with follow-up MRI, were appropriately treated with repeat GKS. Overall survival (OS), neurological survival (NS), qualitative survival (QS) and new lesion-free survival (NLFS) curves were calculated and the prognostic values of covariates were obtained. OS and NS were compared according to tumour number. RESULTS: In total, 1023 separate sessions were required to treat 4562 lesions. The primary organs were lung in 369 patients, gastro-intestinal tract in 70, breast in 33, urinary tract in 24, and others/unknown in 25. The median OS period was 9.0 months. On multivariate analysis, the significant prognostic factors for OS were found to be extracranial disease (risk factor: active), Karnofsky performance status (KPS) score (<70) and gender (male). NS and QS at one year were 85.6% and 73.0%, respectively. The only significantly poor prognostic factor for NS was carcinomatous meningitis. NLFS at 6 months was 68.9%. For both OS and NS, the differences between a few (10) tumours had a significantly poorer prognosis than those with

Heavily T2 weighted MR images of anterior optic pathways in patients with sellar and parasellar tumours - prediction of surgical anatomy.

OBJECTIVE: Location of anterior optic pathways in sellar and parasellar tumours was preoperatively evaluated, by use of heavily T2 weighted MR images. METHODS: Heavily T2 and conventional T1 weighted images were studied in 20 patients with sellar and parasellar tumours who underwent craniotomy. Pathology revealed pituitary adenoma in 5 patients, craniopharyngioma in 8 and parasellar meningioma in 7. Maximum sizes ranged from 15 mm to 58 mm. Sequence parameters of TR/TE for heavily T2 weighted and T1 weighted images were 5800/220 msec and 600/20 msec, respectively, and slice thickness was 3 mm for both. RESULTS: The anterior optic pathway was detected in 95% on heavily T2 weighted images and 50% on T1 weighted images. All preoperative heavily T2 weighted images were compatible with operative findings. The optic chiasms were most commonly supero-posterior in pituitary adenomas, anterior (prefixed) in craniopharyngiomas and posterior in meningiomas. The optic nerves were commonly located superior or lateral to the tumours. However, parasellar meningiomas, off the midline, revealed the optic nerves in various locations, depending on the tumour origin. In such tumours, heavily T2 weighted images provided surgical information on the width of the working space through prechiasmal and/or optico-carotid spaces in the pterional approach. Spatial relation of the tumours to the lamina terminalis, anterior commissure and anterior communicating artery complex was clearly shown in craniopharyngioma patients, who underwent the anterior interhemispheric approach. CONCLUSION: Heavily T2 weighted MR images are useful in determining the location of optic pathways and surgical approach and in individual prediction of the anatomy for even large sellar and parasellar tumours.

Heavily T2-weighted MR imaging of white matter tracts in the hypothalamus: normal and pathologic demonstrations.

BACKGROUND AND PURPOSE: The MR appearance of white matter tracts in the hypothalamus and the role of the hypothalamus as a memory mechanism have not been sufficiently described in clinical settings. Heavily T2-weighted black-and-white reversed (T2R) images were assessed to reveal their visualization and clinical significance. METHODS: One hundred healthy subjects and three patients with hypothalamic lesions underwent fast spin-echo MR imaging to reveal the postcommissural fornix (PF) and mammillothalamic tract (MT). RESULTS: The PF was identifiable in axial and/or coronal sections in all healthy subjects. No remarkable asymmetry of its size or course was evident. Both anteroposterior and vertical dimensions ranged from 10.5 to 14 mm. The MT was visible in one or two axial sections above the mammillary body in 64% of healthy subjects and in a coronal section in 36%. Two patients with glioblastoma multiforme and lacunar infarct at the hypothalamus presented with anterograde amnesia; T2R imaging revealed involvement of both the PF and MT. The third patient had a suprasellar craniopharyngioma with PF injury sparing the MT resulting from surgical manipulation and was free of memory deficit. Anterograde amnesia was evident only when both the PF and MT were injured. CONCLUSION: T2R images have made a high rate of detection of the PF and MT possible and could provide a more detailed correlation of hypothalamic neuroanatomy and memory mechanism in clinical settings.

Bacillus cereus brain abscesses occurring in a severely neutropenic patient: successful treatment with antimicrobial agents, granulocyte colony-stimulating factor and surgical drainage.

Multiple brain and liver abscesses developed immediately after Bacillus cereus bacteremia in a neutropenic patient with acute lymphoblastic leukemia. After even 8 weeks of antimicrobial chemotherapy together with administration of granulocyte colony-stimulating factor, every infectious process disappeared but the patient's headache has still persisted. Because the wall of one brain abscess became thin and was in danger of rupturing into the ventricle, surgical drainage was performed, resulting in disappearance of headache and resolution of brain abscess. The present case indicates that a combined medical and surgical approach is mandatory to treat patients with brain abscesses.

Recurrence of sellar and suprasellar tumors in children treated with hGH--relation to immunohistochemical study on GH receptor.

PURPOSE: GH replacement therapy is required in the majority of children with GH deficiency after treatment of sellar and suprasellar tumors. Owing to the high cell proliferative ability of human GH (hGH), its influence on tumor recurrence has been debated. We retrospectively studied the immunohistochemical expression of the GH receptor in various tumor tissues, in order to investigate the relation between tumor recurrence and hGH replacement. METHODS: GH replacement therapy was performed in 25 patients (8 boys and 17 girls) after the treatment. Tumor recurrence was noted in 4 patients (craniopharyngioma: 2 patients, pilocytic astrocytoma and germinoma: 1 each). Immunohistochemical study of GH receptor in tumor tissue was carried out in those recurrent and recurrence-free cases, by using MAb 263 as a primary antibody. RESULTS: Two patients with recurrent craniopharyngioma were positive for MAb 263, but 1 recurrence-free patient was negative. Patients with pilocytic astrocytoma (recurrent and recurrence-free: 1 each) were all positive. Five patients with germinoma (1 with recurrence and 4 without recurrence) were all negative. CONCLUSION: In the patients with craniopharyngioma treated with GH, a positive immunohistochemical expression of GH receptor in tumor tissue may indicate a high probability of recurrence. In our cases, GH receptor was positive in astrocytomas and negative in germinomas, with or without recurrence. It is therefore speculated that each brain tumor may have its specificity in GH receptor expression.

Incidence of malignant tumors in patients with acromegaly.

Neoplasms may be one of the systemic complications to which we attribute high mortality in acromegaly. The present study was designed to investigate the incidence of malignant tumors in patients with acromegaly in the Japanese population. In this report, 44 patients (25 men and 19 women) with biochemically proven acromegaly were studied retrospectively and had a total 670 patient years of the duration of acromegaly. We investigated the incidence of malignant tumors. There were 5 patients with malignant tumors (5 in men) in this study (11%). Male patients with acromegaly had nearly a 3.5 times higher ratio of malignancy than expected and this increased cancer incidence was considered significant (P=0.01). There was no significant increase in cancer incidence of either the total patient population or female patients. The malignant tumors were two thyroid cancers and one colon, one gastric and one bladder cancer. It is of note that the colon cancer of one patient was diagnosed 2 years after transsphenoidal surgery even though the levels of serum GH and insulin-like growth factor (IGF-1) were reduced to normal after operation. This preliminary study has suggested that male patients with acromegaly might have a high risk of malignancy and that careful screening for tumors is needed both before and after surgical and medical treatment, even in patients with normalized serum GH and IGF-1 levels.

Pre-and post-operative respiratory assessment of acromegalics with sleep apnea--bedside oximetric study for transsphenoidal approach.

PURPOSE: Although routine mechanical nasal packing after transsphenoidal surgery (TS) is thought to increase respiratory disorders during sleep, there has been little in the literature about the pre- and post-operative airway assessment of acromegalics with sleep apnea (SA). We describe 4 acromegalic patients with SA, who underwent transsphenoidal surgery. METHODS AND CASES: The patients were all men, aged from 47 to 59 years. The pre- and post-operative sleep study consisted with a computer calculated oximetry parameter of oxygen desaturation index (ODI), which was defined as the number/hour of oxygen desaturation episodes exceeding 4% from the base line (normal range < 15). The postoperative (postop.) sleep study was carried out from the 1st postop. day to the 8th day, for 1 to 8 days, varying for each patient. RESULTS: Only the worst postop. result is shown. Patient 1 had 2 operations, 2 years apart. ODI was 39.6 before the 1st operation and 45.9 postop.. In the second operation ODI was 21.8 preoperatively (preop.) and 57.9 postop.. Preop. and postop. ODI was 18.1 and 22.2 in patient 2, 21.6 and 22.5 in patient 3 and 45.5 and 18.9 in patient 4, respectively. ODI of patient 4 was 39.6, 3 weeks later. CONCLUSION: Our data showed that the postop. oxymetric study commonly showed worse results in acromegalics with nasal packing. The better result of patient 4 was probably due to a postop. sleepless state. REM sleep usually increases in the first several postop. days, when cardiopulmonary complications are more likely to occur. Since acromegalics with severe SA and postop. nasal packing may more readily suffer from cardiopulmonary complications, postoperative meticulous respiratory monitoring and care should be mandatory.

Bone CT evaluation of nasal cavity of acromegalics--its morphological and surgical implication in comparison to non-acromegalics.

PURPOSE: In order to numerically compare the morphological differences of the nasal cavity and nasal sinus between acromegalics and non-acromegalics, bone window CT scans sliced parallel to the transsphenoidal surgical route were performed. MATERIAL AND CASES: Acromegalic patients had small or large macroadenomas and were 13 (7 men and 6 women) in number, aged 53.2 +/- 16.1 years. Non-acromegalic patients had pituitary tumors and were 44 (21 men and 23 women) in number, aged 52.1 +/- 12.5 years. RESULTS: The results of acromegalics are described in comparison to non-acromegalics in parentheses. a) The width of the surgical corridor: piriform aperture, 27.6 +/- 2.7 (25.9 +/- 2.6) mm; origin of inferior nasal concha, 29.4 +/- 9.4 (26.6 +/- 4.0) mm; and origin of middle nasal concha, 29.8 +/- 3.2 (26.2 +/- 4.2) mm. b) The depth of the surgical corridor: the upper lip thickness, 18.1 +/- 2.7 (13.3 +/- 1.4) mm; the distances between piriform aperture and sphenoid wall, 52.9 +/- 4.6 (49 +/- 4.2) mm; sphenoid wall and sellar floor, 17.3 +/- 4.1 (18.7 +/- 4.1) mm; and sellar floor to dorsum sellae, 17.6 +/- 3.4 (15.6 +/- 4.0) mm. c) Marked carotid prominence: 7/13=53.4% (8/44=18.25%). d) Sinusitis: 8/13=61.5% (12/44=27.3%). DISCUSSION & CONCLUSION: The data presented above show that morphological differences in bony nasal cavity and soft tissue may be responsible for a deeper and narrower surgical field for acromegalics. Acromegalics had a marked carotid prominence more frequently, which needs special attention to avoid carotid injury, when enlarging the surgical field. Knowing these morphological differences will provide useful information for peri- and intra-operative care.

Gamma knife treatment for multiple metastatic brain tumors compared with whole-brain radiation therapy.

OBJECT: The purpose of this retrospective study was to compare the effectiveness of gamma knife radiosurgery (GKS) for multiple cerebral metastases with that of whole-brain radiation therapy (WBRT). METHODS: Ninety-six consecutive patients with cerebral metastases from nonsmall cell lung cancer were treated between 1990 and 1999. The entry criteria were the presence of between one and 10 multiple brain lesions at initial diagnosis, no surgically inaccessible tumors with more than a 30-mm diameter, no carcinomatous meningitis, and more than 2 months of life expectancy. The patients were divided into two groups: the GKS group (62 patients) and the WBRT group (34 patients). In the GKS group, large lesions (> 30 mm) were removed surgically and all other small lesions (< or = 30 mm) were treated by GKS. New distant lesions were treated by repeated GKS without prophylactic WBRT. In the WBRT group, the patients were treated by the traditional combined therapy of WBRT and surgery. In both groups, chemotherapy was administered according to the primary physician's protocol. The two groups did not differ in terms of age, sex, initial Karnofsky Performance Scale (KPS) score, type, lesion number, and size of lesion, systemic control, and chemotherapy. Neurological survival and qualitative survival of the GKS group were longer than those of the WBRT group. In multivariate analysis, significant poor prognostic factors were systemically uncontrolled patients, WBRT group, and poor initial KPS score. CONCLUSIONS: Gamma knife radiosurgery without prophylactic WBRT could be a primary choice of treatment for patients with as many as 10 cerebral metastases from nonsmall cell cancer.

Proliferation, vascular endothelial growth factor expression and cavernous sinus invasion in growth hormone secreting pituitary adenomas.

Surgical cure of growth hormone producing pituitary adenomas (GHomas) becomes difficult when they invade the cavernous sinus (CS). Tumour proliferative activity and angiogenesis are thought to be required for tumour growth and invasion, and vascular endothelial growth factor (VEGF) activates neovascularization around tumours. In this study, the mechanism and clinical significance of CS invasion is analysed. In 25 surgically treated GHomas, the extent of CS invasion was classified as high (Knosp's grade 3 and 4), and low (grade 0, 1 and 2) MR grades, and the MR grades were compared with tumour proliferative potential (Ki-67 expression), angiogenetic demand (VEGF expression), volume of adenomas and serum hormone levels. The Ki-67 index of high MR grade adenomas (1.17 +/- 0.62%) was significantly higher than that of low MR grade adenomas (0.55 +/- 0.42%, p = 0.027), whereas VEGF expression showed no significant correlation with MR grades (p > 0.999). Tumour volume also showed a significant correlation with MR grade (p = 0.002). VEGF expression was not correlated with serum hormone level and volume, but was correlated with tumour proliferative potential. Proliferative potential and tumour volume were two independent factors related to CS invasion. Although VEGF expression was not a direct factor related to CS invasion, it may indirectly play a role in activation of tumour aggressiveness, which is required in CS invasion. Our results show that high MR grade adenomas have higher proliferative ability. In order to improve the surgical outcome, preoperative medical debulking is indicated, particularly, in such adenomas.

Topographical analysis of proliferating cells in meningiomas. Regional heterogeneity of the ability of tumors to proliferate.

Regional heterogeneity of the ability of tumors to proliferate has been pointed out, but its topographical analysis has not been studied in detail. To evaluate the distribution of highly proliferating cells in totally resected meningiomas, seven cases (including one recurrent case) were investigated in this study. Immunostaining of PCNA was performed on the sections crossing the equator of the tumors. These sections were divided into multi-squares with sides of 500 micrometers. The proliferating potential was determined as the PCNA positive cell count in each square. By painting those squares in eight kinds of color corresponding to the value of the PCNA positive cell count, maps of proliferative ability were made. To predict the localization of proliferating cells, we studied these maps in relation to the following: MR image, calcification, distance from the dural attachment and distance from the tumor capsule. Maps of the PCNA positive cell count showed the intra-tumoral heterogeneity of proliferative ability in all cases. Most of the cases showed homogeneous enhancement on MRIs and these images could not be a predicting factor of the highly proliferating area. There was no significant relationship between the calcification and the PCNA positive cell count. Although the proliferating ability was not correlated with the distance from the dural attachment, inner regions distant from the capsule showed higher proliferative ability in all cases. From these results, one should be aware that the information from the samples of meningiomas do not reflect the proliferating ability of the whole tumor.

Sleep-disordered breathing in acromegalics--relation of hormonal levels and quantitative sleep study by means of bedside oximeter.

Sleep-disordered breathing (SDB) is common in patients with growth hormone (GH) secreting pituitary adenomas. Since long-term untreated SDB aggravates systemic conditions (hypertension and arrhythmia etc.), the therapeutic outcome of SDB is important in reducing morbidity and mortality rates. But the results of a quantitative analysis of the lowered GH and IGF-1 levels in SDB in a relatively large number of patients are not detailed. Ten consecutive acromegalic patients were studied with a bedside oximeter. Preoperatively they were divided into two groups based on the presence (SDB group = 6 patients) or absence (non-SDB group = 4 patients) of clinical symptoms of SDB such as habitual snoring, excessive daytime somnolence and nocturnal apneic episodes. The serum IGF-1 averaged 931.7 ng/ml in SDB group and 898.3 ng/ml in non-SDB group. The oxygen desaturation index (ODI) (the number of oxygen desaturations exceeding 4% from the base line) was 29.1+/-15.4 in the SDB group and 2.5+/-1.8 in the non-SDB group (P=0.01). Other oximeter parameters such as the percent of the time spent at O2 saturation < 90% and the mean and the lowest O2 saturations closely correlated with the degree of the clinical symptoms. A postoperative sleep study was conducted in 5 patients in the preoperative SDB group, 4 months or more after the surgery. The serum GH and IGF-1 levels normalized in 3 patients but remained slightly high in 2. ODI became 9.1+/-5.6, which was significantly lower than the preoperative value (P=0.026). One patient had a complete clinical resolution. The other 4 obtained slight to moderate improvement clinically and oximetrically despite normalized or decreased hormonal levels. This study clarified that the response of SDB to lowering of the GH level varies from one patient to another and persisting SDB despite the normalization of the hormonal levels suggests the involvement of other factors in the production of SDB.

Glucose and methionine uptake and proliferative activity in meningiomas.

Despite similar benign histological appearances, proliferative activity of meningiomas varies tumor to tumor, and even region to region in a tumor. To predict proliferative potential before surgery, we compared regional uptake of 2-[18F]fluoro-2-deoxyglucose ([18F]FDG) and L-[methyl-11C]methionine ([11C]MET) with histological indices of tumor proliferative activity in 17 specimens from six patients with meningioma obtained by PET guided stereotactic biopsies. Uptake of [11C]MET, an index of protein synthesis rate, significantly correlated not only with the count of nucleolar organizer regions (NORs), a histological index of protein synthesis, but also with Ki-67 index, a histological index of proliferative activity. On the other hand, [18F]FDG uptake showed no significant correlation with Ki-67 index or clinical malignancy. These results suggest that [11C]MET-PET is a useful tool for predicting tumor proliferative potential in meningiomas.

MRI of growth hormone-secreting pituitary adenomas: factors determining pretreatment hormone levels.

Preoperative serum growth hormone (GH) level is one of the most important determinants of outcome. Our aim was to assess MRI findings which may correlate with pretreatment GH levels in GH-secreting adenomas. We retrospectively studied 29 patients with acromegaly caused by a pituitary adenoma. Tumor size (height, width, thickness and volume), suprasellar extension, sphenoid or cavernous sinus invasion, signal intensity and contrast enhancement were studied. Linear regression analysis or Fisher's exact probability test was used for statistical analysis. Factors related to high GH levels were the maximum dimension of the tumour (r = 0.496, P < 0. 01), its volume (r = 0.439, P < 0.05), spenoid sinus invasion (P < 0. 01) and intracavernous carotid artery (encasement (P < 0.01). The other items were not related to serum GH levels. Since we believe surgery is the first choice of treatment and the cavernous sinus is difficult of access with a conventional surgical approach, preoperative assessment of invasion into the cavernous sinus is critical for predicting the surgical outcome. Low GH levels (5-50 ng/ml) were found with tumours medial to the intercarotid line and high levels (more than 101 ng/ml) with invasive tumours with carotid artery encasement. Variable GH levels were noted with tumours extending beyond the intercarotid line. Because functioning adenomas invading the cavernous sinus tend to have markedly high hormone levels, and only patients with carotid artery encasement showed markedly elevated GH levels, we believe carotid artery encasement a reliable MRI indicator of cavernous sinus invasion.