FLAIR imaging in the follow-up of low-grade gliomas: time to dispense with the dual-echo?

Fluid-attenuated inversion-recovery (FLAIR) imaging has established its utility in neuroimaging. We propose this imaging sequence as a replacement for proton density (PD) and T2-weighted spin-echo sequences in the follow-up of low-grade glioma. 26 MRI examinations of 18 patients with such tumours were reviewed by three neuroradiologists and a neurosurgeon. FLAIR was found to be superior for appreciation of the lesion (91% of studies) and for demonstration of its margin (92%). FLAIR was also better at showing different tumour components, particularly in regions difficult to demonstrate in some planes, such as the vertex in axial imaging. The sequence also defines the postoperative cavity, shows the least amount of susceptibility effect associated with surgical clips, and demonstrates local spread (to white matter tracts, subependymal and capsular) more distinctly. We conclude that FLAIR can replace PD and T2-weighted spin-echo imaging in radiological follow-up of low-grade glioma.     

Does 11C-choline PET-CT contribute to multiparametric MRI for prostate cancer localisation?

Background and purpose

The aim of this work was to determine whether ¹¹C-choline positron emission tomography (PET)–computed tomography (CT) makes a positive contribution to multiparametric magnetic resonance imaging (MRI) for localisation of intraprostatic tumour nodules.

Patients and methods

A total of 73 patients with biopsy-proven intermediate- and high-risk prostate cancer were enrolled in a prospective imaging study consisting of T2-weighted (T2w), dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI and ¹¹C-choline PET-CT before radical prostatectomy. Cancerous regions were delineated on the whole-mount prostatectomy sections and on the different MRI modalities and analysed in 24 segments per patient (3 sections, 8 segments each). To analyse PET-CT images, standardized uptake values (SUV) were calculated per segment.

Results

In total, 1,752 segments were analyzed of which 708 (40.4?%) were found to be malignant. A high specificity (94.7, 93.6 and 92.2?%) but relatively low sensitivity (31.2, 24.9 and 44.1?%) for tumour localisation was obtained with T2w, DCE and DW MRI, respectively. Sensitivity values significantly increased when combining all MRI modalities (57.2?%). For PET-CT, mean SUV_max of malignant octants was significantly higher than mean SUV_max of benign octants (3.68?±?1.30 vs. 3.12?±?1.02, p?<?0.0001). In terms of accuracy, the benefit of adding PET-CT to (multiparametric) MRI was less than 1?%.

Conclusion

The additional value of ¹¹C-choline PET-CT to MRI in localising intraprostatic tumour nodules is limited, especially when multiparametric MRI is used.     

What is to be gained by imaging the same animal before and after treatment?

Experimental design includes decisions to perform measurements with intact animals or truncated in vivo measurements followed by dissection and ex vivo measurements. The design may be driven by advantages and disadvantages of the choices. Analytical results are presented here that can provide a basis for certain experimental design choices. Design considerations include longitudinal studies in the single animal that bracket a treatment, joint observations by supplementing the imaging data with plasma and/or ex vivo sampling after dissection, multiple injections of increasing molar base or administration of a molar dose that results in the occupation of a significant fraction of the target receptors. Of particular interest when constructing an experimental design is the reduction of bias. Analysis tools for this purpose include reparameterization and model application without the formation of time-based averaging.     

Morphometric scores for renal tumors: What does the radiologist need to know?

Numerous therapeutic options are possible in the treatment of renal carcinomas including radical nephrectomy, partial nephrectomy, cryoablation, radiofrequency, active follow-up and among surgical treatments, different approaches may be used such as laparotomy, laparoscopy, robotic-assisted intervention. The choice between these different procedures is partially based on the anatomic conditions of the tumors. Different anatomic scores determined from cross-sectional imaging have been built to predict the complexity of the surgical procedure. The goals of this article are to review the relevant morphologic pattern for management of patients with renal tumors, to know how to calculate these different scores and to understand the clinical applications of these scores.     

With advances in medical imaging can the radiologist reliably diagnose Wilms' tumours?

AIM: To evaluate whether radiologists can accurately differentiate Wilms' tumours from other paediatric abdominal masses with renal involvement using modern imaging methods alone. METHODS: From February 1993 to June 1997, 23 patients presented to the Paediatric Oncology Service at The Royal Hospital for Sick Children, Edinburgh with an intra-abdominal mass which had renal involvement. Nine patients had Wilms' tumours, 12 had neuroblastomas, one patient had xanthogranulomatous pyelonephritis and there was a single case of a mesoblastic nephroma. In each case, two radiologists retrospectively reviewed the initial imaging examinations and independently reached a radiological diagnosis. RESULTS: The radiologists were concordant and reached the correct diagnosis in 20/23 cases (87%), unsure of the diagnosis in one case (4.3 %) and discordant in two cases (8.7 %). Radiologists should be aware that a mesoblastic nephroma can have identical imaging features to a Wilms' tumour. In most cases, ultrasound and a chest X-ray were sufficient to reach the correct diagnosis although computed tomography (CT) and magnetic resonance imaging were superior for demonstrating the relationship of the mass to the great vessels, retroperitoneum and spinal canal. Inferior vena cava invasion was strongly predictive of a Wilms' tumour. Displacement of the great vessels, extension of the mass across the mid-line, renal displacement and tumour calcification on CT were more suggestive of a neuroblastoma although these features were also seen in a significant number of patients with Wilms' tumours. Encasement of vessels by tumour, a paravertebral mass and spinal canal invasion were highly predictive of neuroblastoma. CONCLUSION: In this study, radiologists were accurate at diagnosing Wilms' tumours using modern imaging methods, however, care should be taken in children who are less than 1 year of age as a mesoblastic nephroma may have identical imaging characteristics.     

Endothelin: what does the radiologist need to know?

Endothelin (ET) is a potent endogenous vasoconstrictor peptide. It has been implicated in various pathological states since its discovery in 1988. The cardiovascular system and the kidneys are important sites for the action of this peptide. Two types of ET receptor, ETA and ETB, govern the biological effects of ET. Drugs that can prevent the endogenous synthesis of ET or block its binding to receptors may offer important therapeutic impact to patients with congestive heart failure, pulmonary hypertension and acute renal failure. Areas of particular interest to the radiologist include the role of ET in mediating some of the side effects of contrast media, particularly contrast medium nephropathy, and the involvement of ET in the pathogenesis of restenosis following angioplasty. This review outlines the basic biology of this important mediator and its role in health and disease.     

Is magnetic resonance imaging a viable alternative to ultrasound as the primary imaging modality in the diagnosis of paediatric appendicitis? A systematic review

BackgroundAppendicitis is the most common cause of acute abdominal pain requiring surgical intervention in paediatric patients. Ultrasound is generally the diagnostic imaging modality of choice, followed by CT, where paediatric appendicitis is suspected. However, high operator dependency and diagnostic restrictions related to anatomical and clinical presentation may limit consistency of application. This paper explores whether MRI is a viable alternative to ultrasound as the primary imaging modality.MethodA systematic review of the literature was undertaken. A search of Medline, Cinahl, PubMed Central and Google Scholar was undertaken supplemented by a review of reference lists, author searching and review of NICE evidence base for existing guidelines. Included studies were assessed for bias using the QUADAS-2 quality assessment tool and data were extracted systematically using a purposefully designed electronic data extraction proforma.ResultsSeven studies were included in final review. The age range of participants extended from 0 to 19 years. Only one study with a patient age range of 0–14 used sedation. Sensitivity estimates from the included studies ranged from 92% to 100% while specificity ranged from 89% to 100%. A significant variation in the number and type of sequences was noted between the studies.ConclusionMRI offers high sensitivity and specificity comparable to contrast enhanced CT and greater than ultrasound as reported in the literature. Where accessibility is not a restriction, MRI is a viable alternative to ultrasound in the assessment and diagnosis of paediatric appendicitis. Clinical practice recommendations have been provided to facilitate the translation of evidence into practice.     

Does imaging in sentinel node scintigraphic localization add value to the procedure in patients with breast cancer?

Imaging sentinel nodes with pre-operative lymphoscintigraphy effectively assures successful sentinel node identification. However, sentinel nodes are still identified in the majority of image negative patients. Given the logistics and cost required to perform pre-operative lymphoscintigraphy its routine use may not be justified. It may be valuable for surgeons in the learning phase and in obese patients who have increased risk of intra-operative failed localization. A negative pre-operative lymphoscintiscan predicts inability to localize with the hand-held gamma probe. Patients with no 'hot node' on the lymphoscintiscan are more likely to have failed localization using the gamma probe only. Therefore, blue dye should be used along with the gamma probe to optimize the localization rate in these patients.     

Can cross sectional imaging contribute to the investigation of unexplained child deaths? A literature review

BackgroundThis review examines the factors that can influence an investigation into the unexpected death of a child before considering if using imaging techniques could be of benefit.MethodA systematic search strategy was adopted to search databases using keywords, these results were then subjected to inclusion and exclusion criteria to filter and refine the evidence base further.DiscussionMore research is published on the use of MRI in comparison with other modalities. There is evidence in the case of MRI in particular that its use could be of benefit in identifying and ruling out potential causes of death in children.ConclusionMore research is needed on the use of CT but the routine use of MRI in child death investigation could now be considered. Ethical considerations appear to be a barrier to research in this area and discussions as to how such considerations can be overcome is necessary.     

Quantitative 201Tl SPET imaging in the follow-up of treatment for brain tumour: a sensitive tool for the early identification of response to chemotherapy?

The aim of this study was to establish if repeated quantitative 201Tl SPET scanning during follow-up of astrocytoma therapy can provide information that is relevant for clinical management. Sixteen consecutive patients, with histopathologically verified highly malignant astrocytoma, were followed during PCV chemotherapy. Imaging with 201Tl SPET and CT was performed repeatedly over 8-16 weeks until treatment discontinuation, with a maximum follow-up of 74 weeks. Tumour uptake volume (TUV), a measure of metabolically active tumour tissue, was calculated from the SPET images. The reliability of early identification of treatment failure, defined as > 25% tumour volume increase, following one course (week 8) and three courses (week 24) of chemotherapy, was calculated for the two imaging methods. 201Tl SPET positive patients (> 25% tumour volume increase) were compared with 201Tl SPET negative patients in terms of time to treatment discontinuation (TTD) and survival time (ST). The patients were followed with a total of 59 SPET examinations, and treatment was continued for a median 27 weeks (range 16-78 weeks). The comparative reliability of SPET and CT showed the highest sensitivity and accuracy for SPET in the early identification of astrocytoma treatment failure at the week 24 assessment. Patients with positive 201Tl SPET after three courses of chemotherapy had a significantly reduced TTD (P = 0.040) but not significantly reduced ST. Of the ten patients who received concomitant radiation and chemotherapy, five had a small (0-10 ml) TUV at the week 24 assessment. Patients with a TUV > 10 ml at this assessment had a shorter TTD (P = 0.016) and a reduced ST (P = 0.024) compared to patients with a TUV < 10 ml. In conclusion, the assessment of progressive disease by quantitative 201Tl SPET appears to provide information on treatment response, earlier and with a higher reliability than CT. Repeated 201Tl SPET scanning during follow-up of astrocytoma treatment is an alternative tool for the early identification of treatment failure.     

Does marathon running cause acute lesions of the knee? Evaluation with magnetic resonance imaging

An investigation was conducted into whether running a marathon causes acute alterations in menisci, cartilage, bone marrow, ligaments, or joint effusions, which could be evaluated by magnetic resonance imaging (MRI). Twenty-two non-professional marathon runners underwent MRI of the knee before and immediately after running a marathon. Lesions of menisci and cartilage (five-point scale), bone marrow, ligaments (three-point scale), joint effusion, and additional findings were evaluated and a total score was assessed. Before the marathon, grade 1 lesions of the menisci were found in eight runners, and grade 2 lesions in five runners. After the marathon, an upgrading from a meniscal lesion grade 1 to grade 2 was observed in one runner. Before the marathon, grade 1 cartilage lesions were found in three runners, and grade 2 lesions in one runner, all of which remained unchanged after the marathon. Before and after the marathon, unchanged bone marrow edema was present in three runners and unchanged anterior cruciate ligament lesions (grade 1) were seen in two runners. Joint effusions were present in 13 runners in the pre-run scans, slightly increased in four runners after the marathon, and newly occurred in one runner after the marathon. A total score comprising all knee lesions in each runner showed an increase after the marathon in two runners, whereas no runner showed an improvement of the radiological findings (Wilcoxon signed-rank test, P>0.05). The evaluation of lesions of the knee with MRI shows that marathon running does not cause severe, acute lesions of cartilage, ligaments, or bone marrow of the knee in well-trained runners. Only subtle changes, such as joint effusions or increased intrameniscal signal alterations, were imaged after running a marathon.