Pituitary gland signal in pre-term infants during the first year of life: an MRI study

Our purpose was to determine the pituitary gland signal of premature neonates and infants. We retrospectively measured, in a midline sagittal T1-weighted MRI scan, the pituitary signal of 121 premature infants (mean gestational age: 32.8 weeks, mean chronological age:6.9 months, mean corrected age:5.2 months). The relative signal intensity of the adenohypophysis and neurohypophysis was measured as (A–V)/V and (P–V)/V, respectively (where A, P, V are the mean signal intensities of the adenohypophysis, neurohypophysis and vermis white matter, respectively). On visual inspection the adenohypophysis was rated relative to the vermis white matter (VWM) and scored as hyperintense (grade 3), isointense (grade 2) and hypointense (grade 1). (A–V)/V and (P–V)/V had a negative correlation with chronological age (r=–0.38, r=–0.35, respectively, P<0.01) and corrected age (r=–0.42, r=–0.40, respectively, P<0.01). The (A–V)/V was different in the three grade groups; significant difference was found between grades 3 and 2 and grades 3 and 1. The adenohypophysis was bright in 93% of babies under 2 months of chronological age. In five babies of mean gestational age 29.1 weeks a hyperintense adenohypophysis was observed at 2.9–3.7 months of chronological age (corrected age 0.37–2 months). We conclude that in pre-term babies the adenohypophysis appears in hypersignal that may persist up to 2 months of corrected age. The adenohypophyseal and neurohypophyseal signals decrease with age.     

Contrast between white and grey matter: MRI appearance with ageing

MRI contrast between white and grey matter appears to be higher in young normal subjects than in older patients. The aim of the present study was to investigate the possible relationships between these changes in contrast and ageing. It consisted of two parts. In the first part we retrospectively evaluated 140 MRI brain examinations of healthy subjects, 20 per decade (age range 20–90 years), in whom the contrast was subjectively scored. In the second part we prospectively measured the actual T1, spin density (SD) and T2 values of white and grey matter in another 22 healthy subjects (age range 20–80 years). In the first group of subjects a progressive decrease in white/grey matter contrast was observed with ageing. In the second group of subjects the T1, SD and T2 values of white matter were always shorter than those of grey matter. There is a close relation among T1, SD and T2 values of white and grey matter with ageing. We suggest that there is a progressive loss of white/grey matter contrast with ageing. Such a phenomenon is possibly due to an increased water content in the white matter and the progressive neuronal loss in the grey matter that occurs with age. Correspondence to: S. Magnaldi     

Reproducibility of image interpretation in MRI of the prostate: application of the sextant framework by two different radiologists

The aim of this study was to reproduce prostate cancer (PCA) localization by MRI based on prostatic sextants (right and left base, middle, and apex) with minimal systematic error. Combined endorectal/body-phased-array-coil MRI of the prostate at 1.5 T was retrospectively evaluated twice, with an interval of more than 1 month, by each of two independent radiologists (R1 readings R11 and R12, and R2 readings R21 and R22) in 23 patients (age 51–75 years) who had radical prostatectomy within 1 month of MRI. PCA stage was pT2 in 14 patients, and pT3 in nine. Median Gleason score was 7 (range 5–9). Histopathology showed 83 sextants with PCA and 55 without. Reproducibility of sextant positions was within one MRI slice (3 mm) in over 80% of cases. For PCA localization, ROC analysis (AUC=0.584±0.048–0.724±0.043) yielded no significant intra-reader differences. R11 and R21 differed slightly (P=0.035). Intra-observer agreement (kappa=0.52–0.58) exceeded inter-observer agreement (kappa=0.35–0.45). Intra-observer Spearman correlation (r=0.72–0.74) exceeded inter-observer correlation (r=0.43–0.51) for sextants with PCA, but not for sextants without (r=0.69–0.74). Per-sextant localization and reporting provides a highly reliable framework in MRI of the prostate. MRI of the prostate should be followed up by the same radiologists to minimize systematic error of interpretation.     

Serial MRI changes in radiation myelopathy

Using MRI we assessed the changes in signal, size, and contrast enhancement characteristics of the cervical spinal cord in radiation myelopathy developing after radio-therapy for nasopharyngeal carcinoma. We studied two men and five women, aged 40–77 years. The first MRI study was performed 1–4 months after the initial clinical manifestations of myelopathy, and follow-up MRI 2–22 months after the onset of symptoms. On the first study, all patients showed low signal intensity in a long segment of the cervical spinal cord on T1-weighted images, high signal on T2^*-weighted images, and focal contrast enhancement at C1-2. In five patients there was also swelling of the spinal cord. The site of eccentric focal contrast enhancement correlated with the clinical manifestations. Follow-up imaging less than 10 months after the onset of symptoms showed no significant changes in signal intensity. Focal contrast enhancement at C1–2 remained the same in three patients, was more dense and larger in one, and less dense in another. Subsidence of swelling was seen in two patients. Atrophy of the spinal cord at C1–2, without abnormal signal and with faint contrast enhancement at C1–2 was revealed as early as 10 months after the onset of symptoms, but the contrast enhancement disappeared by 22 months. There was no correlation between clinical manifestations and spinal cord atrophy on MRI.     

The role of MRI in patients with astrocytoma WHO II treated with fractionated stereotactic radiotherapy

Aim of this study was to evaluate the role of pre-therapeutic and follow-up MRI in the clinical treatment and outcome in patients with astrocytoma WHO grade II after fractionated stereotactic radiation therapy (FSRT). One hundred thirty-nine patients with histologically proven astrocytoma WHO grade II were treated with FSRT and retrospectively evaluated. All patients had follow-up MRI studies (Gd-DTPA-enhanced T1- and T2-weighted MR images). Progression-free survival (PFS) and overall survival (OS) rates were calculated using the Kaplan-Meier method. Multivariate analysis was performed on five potential MRI related prognosticators. Median follow-up was 3.8 years. Positive contrast enhancement (CM+) prior to FSRT proved to be a significant prognosticator for PFS and OS (p<0.01). Pre-therapeutic oedema on T2-weighted images and multifocality of contrast medium (CM) enhancement did not prove to be significant prognosticators. Also, diameter and volume of CM enhancement showed no significance on clinical outcome. Negative contrast enhancing (CM–) patients developing a de novo CM enhancement during follow-up showed a significantly worse clinical outcome compared with generally CM– patients (p<0.05). Pre-therapeutic CM enhancement and the development of CM-enhancing areas during follow-up are negative prognosticators for PFS and OS. They must be interpreted as signs of secondary malignity.     

Parotid gland tumors: comparison of conventional and diffusion-weighted MRI findings with histopathological results

Objectives:The aim of this study was to investigate the relationship between pathological classification of parotid gland tumors and conventional MRI – diffusion-weighted imaging findings and also contribute the possible effect of apparent diffusion coefficient (ADC) to diagnosis.Methods:60 patients with parotid masses diagnosed using histopathology and/or cytology were enrolled in this retrospective study. All patients were evaluated using a 1.5 T MRI. Demographic features, conventional MRI findings, and ADC values (mean, minimum, maximum, and relative) were recorded. MRI findings and ADC values were compared between benign–malignant groups and pleomorphic adenoma vs Warthin’s tumor groups.Results:60 tumors (48 benign, 12 malignant) were evaluated in a total of 60 patients (39 males, 21 females). The mean age was 59 (±14, 18–86) years old; the mean lesion size was 26 (±10, 11–61) mm. On the texture of conventional MRI, T2 dominantly hyperintense/with hypointensity signal was seen in 87% of pleomorphic adenomas and T2 dominantly hypointense/with hyperintesity signal was encountered in 64% of all Warthin’s tumors. Seven (28%) Warthin’s tumors were misdiagnosed as pleomorphic adenomas and two others (8%) as malignant tumors. The commonly used mean ADC value was 1.6 ± 0.6 × 10^–3 mm² s⁻¹ for benign tumors, 0.8 ± 0.3 × 10^–3 mm² s⁻¹ for malign tumors, 1 (0.9–1.8) × 10^–3 mm² s⁻¹ for Warthin’s tumors, and 1.9 ± 0.3 × 10^–3 mm² s⁻¹ for pleomorphic adenomas. There was a statistically significant difference in ADC values between benign-malignant tumors and pleomorphic adenomas-Warthin’s tumors.Conclusions:Warthin’s tumor may occasionally be misdiagnosed as pleomorphic adenoma and malignant tumor because of variable morphologic features. In addition to benign–malignant differentiation, the added ADC measurement may also be useful for differentiating Warthin’s tumors from pleomorphic adenomas.     

Comparison of CT,MRI and FDG-PET in response prediction of patients with locally advanced rectal cancer after multimodal preoperative therapy: Is there a benefit in using functional imaging?

The aim of this study was to compare CT, MRI and FDG-PET in the prediction of outcome of neoadjuvant radiochemotherapy in patients with locally advanced primary rectal cancer. A total of 23 patients with T3/4 rectal cancer underwent a preoperative radiochemotherapy combined with regional hyperthermia. Staging was performed using four-slice CT (n=23), 1.5-T MRI (n=10), and ¹⁸F-FDG-PET (n=23) before and 2–4 weeks after completion of neoadjuvant treatment. Response criteria were a change in T category and tumour volume for CT and MRI and a change in glucose uptake (standard uptake value) within the tumour for FDG-PET. Imaging results were compared with those of pretherapy endorectal ultrasound and histopathological findings. Histopathology showed a response to neoadjuvant therapy in 13 patients whereas 10 patients were classified as nonresponders. The mean SUV reduction in responders (60±14%) was significantly higher than in nonresponders (37±31%; P=0.030). The sensitivity and specificity of FDG-PET in identifying response was 100% (CT 54%, MRI 71%) and 60% (CT 80%, MRT 67%). Positive and negative predictive values were 77% (CT 78%, MRI 83%) and 100% (CT 57%, MRI 50%) (PET P=0.002, CT P=0.197, MRI P=0.500). These results suggest that FDG-PET is superior to CT and MRI in predicting response to preoperative multimodal treatment of locally advanced primary rectal cancer.     

Diffusion-weighted MR imaging of pleural fluid: differentiation of transudative vs exudative pleural effusions

The aim of this study was to evaluate the ability of diffusion-weighted MRI in differentiating transudative from exudative pleural effusions. Fifty-seven patients with pleural effusion were studied. Diffusion-weighted imaging (DWI) was performed with an echo-planar imaging (EPI) sequence (b values 0, 1000 s/mm²) in 52 patients. The apparent diffusion coefficient (ADC) values were reconstructed from three different regions. Subsequently, thoracentesis was performed and the pleural fluid was analyzed. Laboratory results revealed 20 transudative and 32 exudative effusions. Transudates had a mean ADC value of 3.42±0.76×10^–3 mm²/s. Exudates had a mean ADC value of 3.18±1.82×10^–3 mm²/s. The optimum cutoff point for ADC values was 3.38×10^–3 mm²/s with a sensitivity of 90.6% and specificity of 85%. A significant negative correlation was seen between ADC values and pleural fluid protein, albumin concentrations and lactate dehydrogenase (LDH) measurements (r=–0.69, –0.66, and –0.46, respectively; p<0.01). The positive predictive value, negative predictive value, and diagnostic accuracy of ADC values were determined to be 90.6, 85, and 88.5%, respectively. The application of diffusion gradients to analyze pleural fluid may be an alternative to the thoracentesis. Non-invasive characterization of a pleural effusion by means of DWI with single-shot EPI technique may obviate the need for thoracentesis with its associated patient morbidity.     

Volumes and growth rates of untreated adult low-grade gliomas indicate risk of early malignant transformation

Adult low-grade gliomas (LGG) grow slowly, but most eventually undergo malignant transformation. The relationship between tumour volume, growth rate and the likelihood of transformation is unknown.Twenty-seven patients with biopsy-proven, untreated LGG had at least three MRI studies at 6 monthly intervals. Tumour volumes and growth rates were calculated using semi-automated segmentation, and analysed in a hierarchical regression model. In a 3-year period, patients who showed clinical deterioration and/or new (or significantly increased) contrast enhancement were classified as transformers (T), whilst non-transformers (NT) remained stable clinically and by conventional radiological criteria.All LGG showed progressive growth. Volumes at study entry were smaller in 9NT (57 ml, 95% CI 35–80 ml) than in 18T (83 ml, 95% CI 70–96 ml) (p = 0.03). Average annual growth rates were lower in NT (16% (95% CI 9–23%)) than in T (26% (95% CI 20–31%)) (p = 0.046), until the penultimate study. Growth in T increased to 56% p.a. (95% CI 20–92%) in the 6 months prior to transformation. In T, tumour volume was the most significant predictor of transformation in the following 12 months.Sequential measurement of LGG volume allows accurate determination of growth rates and identification of patients whose tumours are at high risk of early transformation.     

Diagnosis of chondral lesions of the knee joint: can MRI replace arthroscopy?

The role of magnetic resonance tomography (MRI) for the diagnosis of chondral lesions of the knee joint is still unclear. The sensitivity of the method ranges from 15% to 96%. The scope of our daily experiences showed that there were considerable deviations between the tomographical and arthoscopical results, which vary from the results of experimental studies. Therefore we have conducted a prospective study to investigate the question of how MRI can replace arthroscopy (ASC) in the diagnosis of cartilage damages in the scope of daily routine. All 195 patients included in this study received a magnetic resonance tomography followed by an arthroscopy. A clear diagnosis of supposition had to be determined before the magnetic resonance tomography. The patients were divided into 3 Groups. Group A ( n =86) received a standard Military Hospital Ulm (MH) MRI — sagittal STIR TSE and PD TSE, coronal and transversal T2 FFE (TR=660 ms, TE=18 ms, FA=30°, 512 matrix). In addition, one sub-Group, AK (n =21) was examined with a special cartilage sequence of the cartilage fs T1 W FFE. Neither patients in Group AK nor in Group A as a whole received any contrast medium. Group B (n =88) was examined with an alternate MRI protocol (Radiological Joint Practice, Neu-Ulm — sagittal T1 SE, T2 SE and T2 FLASH (TR=608 ms, TE=18 ms, FA=20°, 256 matrix), coronal PD fs), employing gadolinium as a contrast medium. 156 cartilage lesions were found arthroscopically. In Group A the sensitivity was 33%, the specificity 99%, and the positive and negative prediction values 75% and 98% respectively. Group B reached a sensitivity of 53% and a specificity of 98%. The positive prediction value was 48% and the negative was 98%. Group AK showed a sensitivity of 38% and specificity of 98%; the positive and negative prediction values came to 50% and 97% respectively. In conclusion, our results indicate that the MRI examination techniques recommended in the literature at present are not able to replace the ASC for the diagnosis of cartilage damages of the knee joint. In view of the high specificity (97%–99%) and the high negative prediction value (97%–98%), MRI is suitable for the exclusion of cartilage lesions. For a negative MRI associated with a cartilage injury, a cautious attitude towards an operative cartilage treatment is therefore justified. Because the MRI can not replace the ASC for diagnostic of cartilage damage, the ASC still has to be seen as the method of choice for the evaluation of cartilage damage.     

Abdominal tuberculous lymphadenopathy: MRI features

The aim of this study was to describe the MRI features of abdominal tuberculous lymphadenopathy. MRI studies of 13 patients with abdominal tuberculous lymphadenopathy were reviewed with regard to anatomic distribution and size. Signal intensities, in relation to abdominal wall muscle, on unenhanced T1- and T2-weighted images and patterns of contrast enhancement of lymphadenopathy were evaluated in each patient. In each patient, the largest lymph node with the same imaging characteristic was evaluated. The upper paraaortic region was the most common site of involvement (n=12 patients), followed by the lesser omentum (n=10 patients), the anterior pararenal space (n=9 patients), the lower paraaortic area (n=8 patients), the small bowel mesentery (n=6 patients), the greater omentum (n=2 patients) and the originating site of the inferior mesenteric artery (n=2 patients). The mean lymph node size was 1.8 cm (range 0.5–5 cm). The overall mean lymph node number per patient was 16 (range 2–50). A total of 41 lymph nodes were evaluated in 13 patients. On T2-weighted images, 40 lesions were hyperintense and one lesion was isointense. Nine hyperintense lesions showed a hypointense peripheral rim and seven internal heterogeneïty. Perinodal T2-hyperintensity was present in 23 lesions. The latter finding was valid for all patients. On T1-weighted images, 30 lesions were hypointense and 11 isointense. Nine hypointense lesions demonstrated a hyperintense peripheral rim, and six were heterogeneous. Contrast-enhanced fat-suppressed T1-weighted images demonstrated predominant peripheral enhancement in 28 lesions: (1) peripheral uniform, thin (n=19); (2) thick irregular, complete (n=3); and (3) conglomerate group of nodes showing peripheral and central areas of rim enhancement (n=6). Heterogeneous and homogeneous enhancement was present in ten and three lesions, respectively. Combinations of enhancing patterns in the same nodal group and different nodal groups were seen in eight and nine patients, respectively. Abdominal tuberculous lymphadenopathy may show a variety of signal intensities and patterns of contrast enhancement on MRI. Lymphadenopathy, hypointense on T1-weighted, hyperintense on T2-weighted images with perinodal hyperintensity, and predominant peripheral rimlike enhancement may suggest the diagnosis of tuberculosis.     

Detection of colorectal liver metastases: a prospective multicenter trial comparing unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT

The aim of this study was to compare unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT in the detection of hepatic colorectal metastases. Forty-four patients with hepatic colorectal metastases were examined with unenhanced and MnDPDP-enhanced MRI and with unenhanced and contrast-enhanced spiral CT. The MR examination protocol included baseline T1-weighted spin-echo (SE), T1-weighted gradient-recalled-echo (GRE), and T2-weighted fast-SE sequences; and T1-weighted SE and T1-weighted GRE sequences obtained 30–60 min after administration of 0.5 µmol/kg (0.5 ml/kg) mangafodipir trisodium (MnDPDP). Images were interpreted by three blinded readers. Findings at CT and MRI were compared with those at intraoperative US, which were used as term of reference. Intraoperative US detected 128 metastases. In a lesion-by-lesion analysis, the overall detection rate was 71% (91 of 128) for spiral CT, 72% (92 of 128) for unenhanced MRI, and 90% (115 of 128) for MnDPDP-enhanced MRI. MnDPDP-enhanced MRI was more sensitive than either unenhanced MRI (p<0.0001) or spiral CT (p=0.0007). In a patient-by-patient analysis, agreement with gold standard was higher for MnDPDP-enhanced MRI (33 of 44 cases) than for spiral CT (22 of 44 cases, p=0.0023) and unenhanced MRI (21 of 44 cases, p=0.0013). MnDPDP-enhanced MRI is superior to unenhanced MRI and spiral CT in the detection of hepatic colorectal metastases.     

The clinical impact of thallium-201 reinjection for the detection of myocardial hibernation

Thallium-201 reinjection improves detection of hibernating myocardium in about 30%–50% of persisting defects. The main goal of cardiac revascularization techniques is amelioration of clinical symptoms such as angina and dyspnoea; however, improvement in regional and global pump function is an additional and important target. The aim of this study was to investigate whether fill-in in the reinjection study is correlated with improved contractile function after treatment (percutaneous transluminal coronary angioplasty/aortocoronary bypass surgery). We studied 32 patients with coronary heart disease and impaired regional wall motion (RWM). RWM and ejection fraction (EF) were assessed by analysing ventriculographic images using the centreline method (values in standard deviations from mean values found in a healthy control group). Three²⁰¹T1 single-photon emission tomographic studies (stress, redistribution and reinjection) were performed prior to revascularization and analysed using a bull's-eye scheme. Patients were divided into two groups (group FI-=no fill-in,n=16; group FI+=fill-in,n=16). Fifty-six percent of all patients showed persisting defects, and 56% of these defects showed fill-in after reinjection. Fill-in in our patient group was independent of the size of the persisting defects. After revascularization RWM increased significantly in group FI+ (from –1.9 to 0.0 SD,P<0.001) whereas group FI- showed no significant change (from –1.6 to –1.8 SD). EF increased from –4.3 preoperatively to –2.1 SD postoperatively in group FI+ and did not change significantly in group Fl- (–2.5 to –3.2 SD). The predictive value of reinjection for improvement of RWM was 88%. It is concluded that fill-in in the²⁰¹Tl reinjection image can predict recovery of RWM and EF after revascularization and should be used in all patients with impaired RWM and persisting defects independent of their extent.     

Quantification of magnetization transfer rate and native T1 relaxation time of the brain: correlation with magnetization transfer ratio measurements in patients with multiple sclerosis

The purpose of this paper is to perform quantitative measurements of the magnetization transfer rate (Kfor) and native T1 relaxation time (T1free) in the brain tissue of normal individuals and patients with multiple sclerosis (MS) by means of multiple gradient echo acquisitions, and to correlate these measurements with the magnetization transfer ratio (MTR). Quantitative magnetization transfer imaging was performed in five normal volunteers and 12 patients with relapsing–remitting MS on a 1.5 T magnetic resonance (MR) scanner. The T1 relaxation time under magnetization transfer irradiation (T1sat) was calculated by means of fitting the signal intensity over the flip angle in several 3D spoiled gradient echo acquisitions (3°, 15°, 30°, and 60°), while a single acquisition without MT irradiation (flip angle of 3°) was utilized to calculate the MTR. The Kfor and T1free constants were quantified on a pixel-by-pixel basis and parametric maps were reconstructed. We performed 226 measurements of Kfor, T1free, and the MTR on normal white matter (NWM) of healthy volunteers (n=50), and normal-appearing white matter (NAWM) and pathological brain areas of MS patients (n=120 and 56, respectively). Correlation coefficients between Kfor–MTR, T1free–MTR, and T1free–Kfor were calculated. Lesions were classified, according to their characteristics on T1-weighted images, into isointense (compared to white matter), mildly hypointense (showing signal intensity lower than white matter and higher than gray matter), and severely hypointense (revealing signal intensity lower than gray matter). Dirty white matter (DWM) corresponded to areas with diffused high signal, as identified on T2-weighted images. Strong correlation coefficients were obtained between MTR and Kfor for all lesions studied (r²=0.9, p<0.0001), for mildly hypointense plaques (r²=0.82, p<0.0001), and for DWM (r²=0.78, p=0.0007). In contrast, comparison between MTR and T1free values yielded rather low correlation coefficients for all groups assessed. In severely hypointense lesions, an excellent correlation was found between Kfor and T1free measurements (r²=0.98, p<0.0001). Strong correlations between Kfor and T1free were found for the rest of the subgroups, except for the NAWM, in which a moderate correlation was obtained (r²=0.5, p<0.0001). We conclude that Kfor and T1free measurements are feasible and may improve our understanding of the pathological brain changes that occur in MS patients.     

O-(2-[18F]fluoroethyl)-l-tyrosine PET for monitoring the effects of convection-enhanced delivery of paclitaxel in patients with recurrent glioblastoma

Purpose Convection-enhanced delivery (CED) of paclitaxel is a new locoregional approach for patients with recurrent glioblastoma. The aim of this study was to evaluate O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (FET) positron emission tomography (PET) in monitoring the effects of this type of direct drug delivery.Methods Eight patients with recurrent glioblastoma underwent CED of paclitaxel, which was infused over stereotactically placed catheters into the tumour. FET PET and MRI were performed before and 4 weeks after therapy and then at 3-month intervals to document follow-up. For quantitative evaluation, SUV_max(tumour)/SUV_mean(background) ratios were calculated.Results At baseline all tumours showed gadolinium enhancement and high FET uptake (SUV_max/BG 3.2±0.8). Four weeks after CED, a statistically significant decrease in FET uptake was seen (SUV_max/BG –17%; p<0.01). During follow-up, no recurrence was observed within the CED area. Two out of eight patients with extended tumours died 4 and 5 months after treatment, most probably from local complications. Temporarily stable disease with stable FET uptake was observed in six of eight patients; this was followed by progression and increasing FET uptake ratios (+46%) distant from the CED area in five of the six patients 3–13 months after CED. One patient still presents stable FET uptake 10 months after CED. MRI showed unchanged/increasing contrast enhancement and oedema without ability to reliably assess disease progression.Conclusion FET PET is a valuable tool in monitoring the effects of CED of paclitaxel. In long-term follow-up, stable or decreasing FET uptake, even in contrast-enhancing lesions, is suggestive of reactive changes, whereas increasing ratios appear always to be indicative of recurrence. Therefore, FET PET is more reliable than MRI in differentiating stable disease from tumour regrowth.     

Assessment of the pathological grade of astrocytic gliomas using an MRI score

To evaluate the usefulness of an MRI score for identifying tumour tissue characteristics, 41 histologically verified supratentorial astrocytic gliomas, including 13 low-grade astrocytomas (LGA) 14 anaplastic astrocytomas (AA) and 14 glioblastoma multiformes (GBM), were examined with a 0.5T superconductive MR imager. Nine MRI criteria were used: heterogeneity (HET), cyst formation or necrosis (CN), haemorrhage (HEM), crossing the midline (CM), oedema or mass effect (EM), border definition (BD), flow void (FV), degree (CE-D) and heterogeneity (CE-HET) of contrast enhancement; Gd-enhanced T1-weighted images were obtained in 32 cases (10 LGA, 10 AA, and 12 GBM). Each of the criteria was scored and analysed statistically. The mean values of LGA, AA and GBM were 0.45±0.31, 1.18±0.20, and 1.47±0.22, respectively. The MRI score increased with the pathological grades (P<0.01–0.001). LGA had significantly lower values than AA in five (HET, CN, EM, BD, CE-D) of the nine criteria (55.6%) and lower values than GBM in all except HEM (88.9%). Three criteria (33.3%): HET, CN, and FV were significantly higher in GBM than AA. CE-D, HET, EM, CN, and CE-HET proved to be related to the pathological grade by a multiple regression analysis (P<0.001).     

Evaluating the severity of nonalcoholic steatohepatitis with superparamagnetic iron oxide‐enhanced magnetic resonance imaging

Purpose

To evaluate the utility of noninvasive assessment of human nonalcoholic fatty liver disease (NAFLD) patients using superparamagnetic iron oxide (SPIO)‐enhanced MRI.

Materials and Methods

Nineteen NAFLD patients underwent SPIO‐enhanced MRI. The values of τ, a time constant for an exponential approximation, were calculated using gradient‐echo echo‐planar imaging, and the values of %T2, a marker of the T2 relaxation effect of SPIO, were calculated using T2‐weighted fast spin‐echo images. Correlations between these values and the histological NAFLD activity scores were evaluated. The study protocol was approved by our Institutional Review Board and all patients gave informed consent.

Results

There was a statistically significant relationship between the NAFLD activity scores and the τ values (r = 0.66, P = 0.002). The %T2 values were also significantly correlated with the NAFLD activity score (r = ?0.58, P = 0.009). A cutoff τ value of 42.8 predicted “definitive NASH” (NAFLD activity score ≥5) with a specificity of 66.7% and a sensitivity of 99.9%, whereas a cutoff %T2 value of 32.5 predicted “definitive NASH” with a specificity of 72.7% and a sensitivity of 87.5%.

Conclusion

Noninvasive SPIO‐enhanced MRI may be helpful for identifying NASH patients among patients suspected of having NAFLD. J. Magn. Reson. Imaging 2008;28:1444–1450. © 2008 Wiley‐Liss, Inc.

     

CT-guided radiofrequency ablation of osteoid osteoma: long-term results

The aim of the study was to assess the safety and efficacy of CT-guided percutaneous radiofrequency (RF) ablation of osteoid osteoma (OO). From 1997 to 2001, RF ablation was performed on 38 patients with OO, diagnosed clinically and by radiography, scintigraphy, contrast-enhanced MRI, and CT. Treatment was performed via percutaneous (n=29) or surgical (n=9) access, under CT guidance in all cases, with an 18-gauge straight electrode. Patients were discharged within 24 h and followed up clinically (at 1 week and every 6–12 months) and with MRI (at 6 months) and scintigraphy (after 1 year). The technical success rate was 100%. Complications occurred in two patients, consisting in local skin burns. The follow-up range was 12–66 months (mean ± SD, 35.5±7.5 months). Prompt pain relief and return to normal activities were observed in 30 of 38 patients. Persistent pain occurred in eight patients; two patients refused further RF ablation and were treated surgically; RF ablation was repeated in six cases achieving successful results in five. One patient reported residual pain and is being evaluated for surgical excision. Primary and secondary clinical success rates were 78.9 (30/38 patients) and 97% (35/36 patients), respectively. CT-guided RF ablation of OO is safe and effective. Persistent lesions can be effectively re-treated. Several imaging modalities are needed for the diagnosis of OO and for the follow-up after treatment, particularly in patients with persistent symptoms.     

Quantitative MRI of the brain in children with sickle cell disease reveals abnormalities unseen by conventional MRI

Conventional MRI (cMRI) has shown that brain abnormalities without clinical stroke can manifest in patients with sickle cell disease (SCD). We used quantitative MRI (qMRI) and psychometric testing to determine whether brain abnormalities can also be present in patients with SCD who appear normal on cMRI. Patients 4 years of age and older with no clinical evidence of stroke were stratified by cMRI as normal (n = 17) or abnormal (n = 13). Spin-lattice relaxation time (T1) of gray and white matter structures was measured by the precise and accurate inversion recovery (PAIR) qMRI method. Patient cognitive ability was assessed with a standard psychometric instrument (WISC-III or WISC-R). In all 30 patients with SCD, qMRI T1 was lower than in 24 age- and race-matched controls, in cortical gray matter (P < .0006) and caudate (P < .0009), as well as in the ratio of gray-to-white matter T1 (P < .008). In the 17 patients who were shown to be normal by cMRI, qMRI T1 was still lower than in controls, in both cortical gray matter (P < .02) and caudate (P < .004). Histograms of voxel T1 show that the proportion of voxels with T1 values intermediate between gray and white matter (ie, consistent with encephalomalacia) was 9% higher than controls in patients shown to be normal by cMRI (P < .05) and 15% higher than controls in patients shown to be abnormal by cMRI (P < .0005). The full scale intelligence quotient (FSIQ) of all patients with SCD was 75, compared to the FSIQ of 88 in a historical control group of patient siblings (P < .001). The FSIQ of patients shown to be normal by cMRI was 79, significantly lower than the FSIQ of patient siblings (P < .04). The FSIQ of 71 in patients shown to be abnormal by cMRI was significantly lower than both the patient siblings (P < .005) and the patients shown to be normal by cMRI (P < .04). Patients shown to be abnormal by cMRI scored lower than patients shown to be normal by cMRI, specifically on the subtests of vocabulary (P = .003) and information (P = .03). Cognitive impairment is thus significant, even in patients with SCD who were shown to be normal by cMRI, suggesting that cMRI may be insensitive to subtle neurologic damage that can be detected by qMRI. Because cognitive impairment can occur in children normal by cMRI, our findings imply that prophylactic therapy may be needed earlier in the course of SCD to mitigate neurologic damage.     

Malignant biliary obstruction: treatment with self-expandable metallic stents

In a 3-year period, 57 self-expandable metallic biliary stents (Wallstent) were successfully placed in 49 patients with malignant biliary obstruction. Thirty-three of our patients have died. In this group follow-up was 1–12 months with a mean of 4.5 months and stent patency was 1–12 months with a mean of 4.3 months. Sixteen patients are still alive. In this group, follow-up was 2–26 months with a mean of 8.4 months and stent patency was 1–18 months with a mean of 6.8 months. In 4 patients a secondary stent was used due to malpositioning during deployment. In 1 patient bilateral drainage was achieved with two stents. Four patients required 5 reinterventions due to reocclusion, with a reocclusion rate of 9.4 %; 3 of them were treated with secondary metallic stents, 1 with a conventional stent and the remaining 1 with balloon dilatation. Thirty-day mortality rate was 8.1 % and procedure-related mortality was 2 %. Major and minor complication rates were 10 % and 22 %, respectively. Self-expandable metallic stents provide good palliation in patients with malignant biliary obstruction. Correspondence to: M. N. Özmen