MRI of pituitary macroadenomas with reference to hormonal activity

Summary In 115 patients with pituitary macroadenomas, the findings on mid-field MRI were correlated with the hormonal activity of the tumours. Adenomas secreting growth hormone (GH), prolactin (PRL) and clinically nonsecretory adenomas were studied. Tumour size, invasiveness and signal intensity patterns were recorded. Relaxation times and ratios of signal intensity and proton density (relative to the corpus callosum) were analysed in areas of apparently solid tissue in a subgroup of 59 previously untreated patients. Invasiveness was more common in PRL-and GH-secreting adenomas than in the nonsecreting ones. Diffuse invasion of the base of the skull was most common in prolactinomas, and associated with a lower frequency of suprasellar tumour extension. In prolactinomas, a correlation was found between the maximum serum PRL level and tumour size. Haemorrhagic, cystic or necrotic areas were less common in GH-secreting tumours than in the other types. Haemorrhage was more common in prolactinomas than in nonsecreting tumours. MR parameters were similar in prolactinomas and nonsecreting adenomas, but indicated a smaller amount of water in GH-secreting tumours.     

Intrapituitary fluid levels following haemorrhage: MRI appearances in 13 cases

Demonstration of fluid levels on MRI is well recognised in cerebral haematomas, tumours and cysts. The occurrence of fluid levels within haemorrhagic pituitary tumours has not previously been described in detail. Evidence of haemorrhage was identified in 27 of 125 pituitary tumours. Fluid levels occurred in 13 of these haemorrhagic tumours. No association with histological type was identified. Recognised risk factors for haemorrhage were identified in half of the cases. Received: 22 December 1997 Accepted: 23 June 1998     

Metastases to the pituitary-hypothalamic axis

Summary Seven patients with metastatic tumour in the pituitary-hypothalamic axis were investigated by MRI. The main clinical problems were diabetes insipidus (5 cases) and general pituitary dysfunction (2 cases). No patient had visual or oculomotor symptoms. In 6 of the 7 patients the primary malignant tumour was known, but no patient had symptoms from the primary tumour; 1 had symptoms from metastases in locations other than the pituitary gland. In one patient no primary tumour was known. MR detection of a second, clinically silent, 5 mm lesion in the posterior cranial fossa initiated the search for primary tumour. MRI showed purely suprasellar tumours in 3 patients and intra- and suprasellar tumours in 4. The latter were dumbbell lesions with only a small bridge of tissue connecting the intra- und suprasellar portions. Six of the 7 suprasellar tumours seemed to be in the infundibular recess of the third ventricle; in 5 the infundibulum was visible as an enhancing linear structure at the postero-inferior border of the tumour. The pituitary fossa was normal in all cases.     

MRI of pituitary adenomas: the position of the normal pituitary gland

The position of the normal pituitary gland, assessed using gadolinium-enhanced MRI was compared with the position found at surgery for pituitary adenoma in 25 patients. The tumours were five microadenomas and 20 macroadenomas. Using T1-weighted imaging, the anterior lobe could be differentiated on the sagittal image in five patients (20%) and on the coronal image in four (16%). The high intensity of the posterior lobe could be differentiated using T1-weighted sagittal imaging in 13 patients (52%). The normal pituitary gland, which enhanced more strongly than tumour, could be differentiated using Gd-DTPA-enhanced MRI on the sagittal images in 22 cases (88%) and on the coronal image in 17 (68%). In seven patients, the normal pituitary gland surrounded the tumour; it was displaced superiorly in 14 cases and superioposterorly in two but in no case was it displaced anteriorly or downwards.     

Malignant peripheral nerve sheath tumours in neurofibromatosis type 1: MRI supports the diagnosis of malignant plexiform neurofibroma

Plexiform neurofibroma (PNF) is a typical feature of neurofibromatosis 1 (NF1). About 10% of patients with NF1 develop malignant peripheral nerve-sheath tumours (MPNST), usually arising from PNF, and this is the major cause of poor survival. A better prognosis can be achieved if the tumours are diagnosed at an early stage. Our objective was to establish MRI criteria for MPNST and to test their usefulness in detecting early malignant change in PNF. MRI was performed on 50 patients with NF1 and nerve-sheath tumours, of whom seven had atypical pain, tumour growth or neurological deficits indicative of malignancy; the other 43 were asymptomatic. On MRI all seven symptomatic patients had inhomogeneous lesions, due to necrosis and haemorrhage and patchy contrast enhancement. In one patient, the multiplicity of confluent tumours with inhomogeneous areas in addition to central lesions did not allow exclusion of malignancy. Only three of the 43 asymptomatic patients had comparable changes; the other 40 patients had tumours being of relatively homogeneous structure on T1- and T2-weighted images before and after contrast enhancement. All three asymptomatic patients with inhomogeneous lesions were shown to have MPNST.     

The role of somatostatin receptor scintigraphy in patients with pituitary adenoma or post-surgical recurrent tumours

To assess the role of scintigraphy with 111In-DTPA-D-Phe-octreotide (111In-octreotide) in the diagnosis of pituitary adenomas and in the evaluation of post-surgical recurrent or residual tumours, we performed scintigraphy with 111In-DTPA-D-Phe-octreotide (SRS) in 35 patients: 14 patients with confirmed pituitary tumours and 15 with confirmed recurrent tumours. Clinical, biochemical and histological analyses, conventional images (CT/MRI), and follow-up assessments during a period of 1 year to 4 years were recorded in all patients. In the present study, scintigraphy with 111In-octreotide showed positive uptake in 10 out of 14 patients with confirmed pituitary tumour and in 13 out of 15 patients with confirmed recurrent tumour, with an overall sensitivity of 79%. SRS showed better results in growth hormone (GH)- and prolactin (PRL)-secreting tumours (7/8 patients correctly identified) than in other adenomas (3/9). SRS detected recurrence of adenocorticotrophic hormone (ACTH)-secreting tumours (4/5 patients correctly identified) and non-secreting tumours (5/7 patients correctly identified). 111In-octreotide scintigraphy, in combination with other imaging modalities, is useful in the diagnosis and follow-up of pituitary tumours. It allows scar tissue to be differentiated from tumour recurrence after surgical treatment and ensures better selection of patients who will benefit from medical treatment with somatostatin analogues.     

Lesions of the brain stem: assessment by magnetic resonance imaging

Summary Ninety-six magnetic resonance imaging (MRI) studies demonstrating solitary brain stem lesions were reviewed in order to establish distinguishing features between tumours and other lesions. Histological confirmation of the radiological diagnoses was obtained in 33% of patients. The morphology of the lesion rather than its signal characteristics was the most useful feature in differential diagnosis, except after haemorrhage. However, areas of abnormal T2 recovery time were significantly more extensive than areas of abnormal T1 recovery time in tumours at presentation. In other lesions and in tumours following radiotherapy induced regression, the extent of abnormal T1 and T2 signal was the same. Possible reasons for this observation are discussed. The accuracy of computed tomography (CT) and MRI were similar for lesions causing brain stem expansion but for small lesions MRI was more sensitive and provided better topographical information.     

CT and MRI of haemorrhage into intracranial neuromas

Six patients with haemorrhage into intracranial neuromas were studied by computed tomography (CT) and magnetic resonance imaging (MRI) at 0.5 T with spinecho pulse sequences. The nature of the tumour and the presence of a haematoma were confirmed by surgery and microscopic examination in all cases. Four neuromas arose from the acoustic nerves and two from the trigeminal. Four of the six patients suffered from sudden onset or rapid worsening of symptoms including headache, vertigo and/or hemifacial motor and sensory disturbances. CT in the acute stage revealed a hyperdense area or a fluid-fluid level (FFL). The hyperdense area disappeared on CT repeated in the chronic stage. On MRI in subacute and chronic stages the haemorrhage showed hyperintensity on both T1 and T2 weighting in five cases examined between 16 and 46 days after the onset, and isointensity on T1 weighting and an FFL on T2 weighting in one case examined 12 days after the onset of symptoms. A well-defined low intensity rim indicating prior haemorrhage was observed on T2-weighted images in three cases. MRI was more effective than CT in detecting haemorrhage into the tumours and in staging it.     

Magnetic resonance imaging of the pituitary gland

Magnetic resonance imaging (MRI) was performed on 22 patients with a wide spectrum of pituitary disease and on 17 control subjects, in order to determine whether MRI is useful in localising and determining the extent of involvement of large and small pituitary tumours. The results indicate that MRI, with an 0.5 T superconducting magnet (Elscint, Israel), can be used to visualise large pituitary tumours and to determine the extent of parasellar and suprasellar involvement. The 'empty sella' syndrome can also be easily and confidently diagnosed. Some microadenomas can be visualised despite the relatively thick slices (0.7 cm) used in this study. These findings suggest that MRI in its current state of development is very useful in evaluating large pituitary lesions. With further technical refinements, improving the spatial resolution and decreasing slice thickness, this technique may come to be of some importance in the evaluation of pituitary microadenomas.     

CT and MR compared in the study of hypophysis

Normal CT and MR anatomy was studied in two series (53 and 25 cases respectively) of young volunteers of both sexes, asymptomatic and certainly without lesions of the pituitary gland. 115 other pathological cases (73 hyperprolactinemias, 8 acromegalies, 15 Cushing syndromes, 2 hyperthyroidisms, 17 nonsecreting adenomas) were examined using both CT and MRI. Both an accurate review of the relative literature and the results of our own series prove that MR is superior to CT in diagnosing pituitary microadenomas (3.2% not diagnosed with MRI and 25.8% not diagnosed with CT), in the follow-up of prolactinomas subjected to medical therapy and in the study of extrasellar involvement of pituitary adenomas, particularly with regard to the demonstration of compression of the optic chiasma.     

Intracranial metastases of hepatocellular carcinoma: CT and MRI

We report clinical characteristics and CT and MRI in 16 patients with brain metastases due to hepatocellular carcinoma (HCC). Eight of these 16 patients presented with apoplexy-like symptoms (50 %). Pulmonary metastases were found in 13 cases (81.3 %). The mean survival from the appearance of cerebral metastases to death was 6.2 weeks, which is one of the shortest survival terms in metastatic brain tumours. Haemorrhagic brain metastases were observed in 14 patients (87.5 %) with a tendency for the frequency of bleeding to increase in proportion to the size of the tumour. On both contrast-enhanced CT and MRI, metastatic brain tumours enhanced strongly, suggesting that brain metastases, like HCC, are also hypervascular. MRI is useful in evaluating brain metastases from HCC, especially in order to differentiate tumour from haemorrhage. Our results demonstrated a poor prognosis and bleeding tendency of brain metastases due to HCC and showed the usefulness of CT and MRI in achieving a correct diagnosis.     

Pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions: differentiation using MRI

AIMS: To determine the differential magnetic resonance imaging (MRI) features of pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions. MATERIALS AND METHODS: The MRI images of 64 patients with pituitary adenoma (n=38), craniopharyngioma (n=13), or Rathke cleft cyst (n=13) were retrospectively reviewed by three neuroradiologists. The following characteristics were evaluated: shape, volume, extent, component characteristics, signal intensities of solid portions on T2-weighted images, signal intensities of cystic portions on T1-weighted images, and enhancement patterns of solid portions and cyst walls of tumours. Fisher's exact test applied with Bonferroni correction was used for multiple comparison. A flowchart for differential diagnosis was constructed based on statistical analysis of the results. RESULTS: A snowman shape, solid characteristics, and homogeneous enhancement of the solid portion were more common in pituitary adenomas (p<0.017). A superiorly lobulated shape, third ventricle compression by superior tumour extension, mixed solid and cystic characteristics, and reticular enhancement of the solid portion were more common in craniopharyngiomas (p<0.017). Finally, an ovoid shape, a small tumour volume, cystic characteristics, and no or thin cyst wall enhancement were more common in Rathke cleft cysts (p<0.017). The flowchart yielded diagnostic accuracies as follows: 92.1% in pituitary adenoma; 92.3% in craniopharyngioma; 92.3% in Rathke cleft cyst; and 92.2% overall. CONCLUSION: A combination of MRI findings is helpful in the differential diagnosis of the three tumours involving both intrasellar and suprasellar regions.     

How often is haemosiderin not visible on routine MRI following traumatic intracerebral haemorrhage?

Intracerebral haemorrhage may be visible indefinitely on MRI, due to persistence of haemosiderin in macrophages around the lesion, but it is not clear whether all haemorrhages produce haemosiderin or, if not, what proportion cannot be identified as former haemorrhages on routine MRI. We performed routine MRI (spin-echo T2- and proton-density weighted images) in 116 survivors of moderate to severe head injury, 1–5 years after injury. We reviewed the images blindly and correlated them with CT in the acute stage, to determine how many haemorrhages from the acute stage were identifiable by virtue of haemosiderin deposition on late MRI. Of 106 haemorrhages in 78 patients on CT at the time of injury, 96 (90 %) were visible as haemosiderin on late MRI. Of the old haemorrhages without haemosiderin, seven of ten were in patients where another haemorrhage with haemosiderin was still visible elsewhere in the brain. No patient or haemorrhage features explained the formation or absence of haemosiderin. Thus about 10 % of definite haematomas show no trace of haemosiderin on routine spin-echo MRI. Radiologists should be alerted to supplement routine spin-echo with gradient-echo sequences if there is a reason to suspect, or specifically exclude, prior haemorrhage. Received: 20 April 1999/Accepted: 1 July 1999     

Tumor R2* is a prognostic indicator of acute radiotherapeutic response in rodent tumors

PURPOSE: To test the prognostic potential of tumor R2* with respect to radiotherapeutic outcome. Blood oxygenation level dependent (BOLD) MRI images are sensitive to changes in deoxyhemoglobin concentration through the transverse MRI relaxation rate R2* of tissue water, hence the quantitative measurement of tumor R2* may be related to tissue oxygenation. METHODS AND MATERIALS: Tumor growth inhibition in response to radiation was established for both GH3 prolactinomas and RIF-1 fibrosarcomas with animals breathing either air or carbogen during radiation. In a separate cohort, the baseline R2* and carbogen (95% O2, 5% CO2)-induced DeltaR2* of rat GH3 prolactinomas and murine RIF-1 fibrosarcomas were quantified using multigradient echo (MGRE) MRI prior to radiotherapy, and correlated with subsequent tumor growth inhibition in response to ionizing radiation, while the animals breathed air. RESULTS: A radiation dose of 15 Gy caused pronounced growth delay in both tumor models and transient regression of the GH3 prolactinomas. When the animals breathed carbogen during radiation, the growth delay/regression was enhanced only in the GH3 prolactinomas. The GH3 prolactinomas, which exhibit a relatively fast baseline R2* and large DeltaR2* in response to carbogen breathing prior to radiotherapy, showed a substantial reduction in normalized tumor volume to 66 +/- 3% with air breathing and 36 +/- 5% with carbogen seven days after 15 Gy irradiation. In contrast, the effect of 15 Gy on the RIF-1 fibrosarcomas, which give a relatively slow baseline R2* and negligible DeltaR2* response to carbogen prior to treatment, showed a much smaller growth inhibition (143 +/- 3% with air, 133 +/- 12% with carbogen). CONCLUSION: Quantitation of tumor R2* and carbogen-induced DeltaR2* by MGRE MRI provides completely noninvasive prognostic indicators of a potential acute radiotherapeutic response.     

MRI versus CT in the diagnosis of Nelson's syndrome

The purpose of the study was to evaluate the utility of MRI and CT in the diagnosis of Nelson's syndrome, i. e. pituitary tumours in patients bilaterally adrenalectomized for Cushing's disease. Thirteen patients, followed up for 5–29 years after adrenalectomy, were studied. In 6 of them CT and MRI revealed no changes in the pituitary gland. In the remaining 7 patients only three CT scans were suggestive of a pituitary adenoma. MRI studies with administration of gadodiamide confirmed the CT diagnosis of Nelson’s tumour in 3 patients and disclosed microadenomas in a further 4 patients. Neurosurgical treatment in 4 patients confirmed the MRI findings. Additionally CT and MRI examinations were performed in 5 patients suspected of a recurrent Nelson's tumour 3–11 years after neurosurgery. MRI visualized recurrent adenomas in 3 patients that were not well seen by CT scans. In our experience MRI was more effective than CT in the diagnosis of Nelson's syndrome. Received 17 October 1995; Revision received 25 January 1996; Accepted 31 January 1996     

201Tl SPET in the differential diagnosis of brain tumours.

The aims of this study were to assess the utility of 201Tl single photon emission tomography (SPET) in the differential diagnosis of brain tumours and to elucidate the relationship between 201Tl tumour uptake and degree of contrast-enhancement on magnetic resonance imaging (MRI). Early (15 min) and delayed (3 h) 201Tl SPET imaging and T1-weighted MRI were performed before and after Gd-DTPA enhancement in 101 (41 malignant and 60 benign) untreated brain tumours. The 201Tl uptake ratio (tumour-to-normal brain count ratio) for both the early and delayed SPET studies and the retention index (the ratio of delayed to early 201Tl uptake) were calculated. Malignant tumours were separated from benign tumours with 87% accuracy based on the assumption that tumours with a 201Tl retention index < 0.7 or no abnormal uptake are benign. Meningiomas and pituitary adenomas were differentiated from other benign tumours by their characteristic pattern on SPET. The degree of contrast-enhancement of the tumour on MRI was concordant with the early 201Tl uptake ratio for most histological types. However, schwannomas and cavernous haemangiomas showed a low 201Tl uptake ratio in spite of a high degree of contrast-enhancement on MRI. In conclusion, 201Tl SPET provides additional information that helps in the differential diagnosis of brain tumours.     

Spinal tumours in neurofibromatosis type 1: an MRI study of frequency, multiplicity and variety

In neurofibromatosis type 1 (NF1) spinal tumours cause neurological symptoms in about 2 % of patients. Among over 1400 patients with NF1 we saw symptomatic spinal tumours in 23 (1.6 %). MRI of the entire spinal canal was obtained in 54 patients aged 5–56 years with NF1. The number, site, morphology and signal characteristics of the spinal tumours were recorded and analysed. There were 24 patients with symptoms such as sensory impairment or paralysis; 30 patients had no neurological deficits. Of the 24 symptomatic patients, 23 (96 %) had spinal tumours, while we saw spinal tumours in 12 (40 %) of the 30 patients without neurological deficits. No spinal segment was preferred in symptomatic or asymptomatic patients. Most intraspinal extramedullary tumours were primarily extradural and intraforaminal. MRI showed intramedullary tumours in 3 patients (6 %), intraspinal extramedullary tumours in 18 (33 %) and intraforaminal tumours in 31 (57 %). Only neurological deficits in patients with NF1 should prompt further diagnostic clarification. In patients with neurological symptoms there may be a multiplicity of masses in the spinal canal, which can lead to difficulties in attaching symptoms to a certain tumour. In patients who do not satisfy the NIH criteria, it can be a helpful observation that spinal tumours in NF1 are primarily intraforaminal, extending into the spinal canal, while in NF2 they are mostly intraspinal intradural tumours. Received: 7 April 1998 Accepted: 15 December 1998     

MRI of intracranial germ-cell tumours

Our aim was to review the MRI appearances of primary intracranial germ-cell tumours (GCT). We reviewed the MRI studies of 32 patients: 19 with germinomas, five with teratomas, one with an embryonal carcinoma, five with mixed and two with malignant nongerminomatous GCT. Eleven were in the pineal region, 12 suprasellar, five in the both sites, two in the basal ganglia and two in the corpus callosum. Contrast-enhanced images were available for 27 patients. The solid parts of GCT were nearly isointense with grey matter on both T1- and T2-weighted images. In seven patients with nongerminomatous GCT high-signal components were found on T1-weighted images, representing haemorrhage, high-protein fluid or fat. Cystic components were detected in 17 of 27 patients; eight germinomas and all nine nongerminomatous GCT had cysts. The solid components of germinomas enhanced homogeneously in eight cases and heterogeneously in 10, while all nongerminomatous GCT showed heterogeneous enhancement. MRI features tumours can facilitate correct diagnosis of GCT, including histological subtypes.     

垂体泌乳素瘤伽玛刀治疗后的MRI研究

目的 探讨伽玛刀治疗泌乳素瘤（PRL）的临床疗效及MRI的影像学变化。资料与方法 回顾性分析78例PRL伽玛刀治疗后的MRI随访影像资料,平均随访期32．5个月（12～96个月）,评价MRI在PRL伽玛刀治疗后影像学变化中的作用。结果 78例中肿瘤完全消失35例（占44．9％）,肿瘤体积缩小37例（占47．4％）,体积无变化6例（占7．7％）,肿瘤总控制率100％。2例肿瘤伽玛刀治疗后3和9个月出现一过性坏死肿胀。临床症状总改善率为73例（93．6％）,其中12个月以内改善率为62例（79．5％）。结论 伽玛刀治疗PRL能够很好地控制肿瘤生长和PRL过量分泌,这种作用随着随访时间延长具有放大效应。     

The value of MRI in angiogram-negative intracranial haemorrhage

In one year, cerebral angiograms were performed for intracranial haemorrhage (ICH) on 334 patients. No cause for haemorrhage could be identified in 41 (12%), 30 of whom had predominantly subarachnoid (SAH) and 11 predominantly parenchymal haemorrhage (PH). These patients were prospectively examined by cranial MRI 1–6 weeks after the ictus. The MRI studies were positive in 7 patients (17%). In the 30 patients examined after SAH, 2 studies were positive, showing an aneurysm in one case and a brain stem lesion of uncertain actiology in the other. In those examined after PH, cavernous angiomas were shown in 2, a tumour in 1 and a vascular malformation in another; useful diagnostic information was thus obtained in 36% of this group.