What and how should we measure in paediatric oncology FDG-PET/CT? Comparison of commonly used SUV metrics for differentiation between paediatric tumours.

BACKGROUND: In clinical routine, SUVmax and SUVpeak are most often used to determine the glucose metabolism in tumours by 18F-FDG PET/CT. Both metrics can be further normalised to SUVs in reference regions resulting in a SUV ratio (SUVratio). The aim of the study was to directly compare several widely used SUVs/SUVratios with regard to differentiation between common tumours in paediatric patients; a special focus was put on characteristics of reference region SUVs. METHODS: The final study population consisted of 61 children and adolescents with diagnoses of non-Hodgkin lymphoma (NHL, n = 25), Hodgkin lymphoma (HL, n = 14), and sarcoma (n = 22). SUV metrics included SUVmax and SUVpeak as well as both parameters normalised to liver and mediastinal blood pool, respectively, yielding the SUVratios SUVmax/liver, SUVmax/mediastinum, SUVpeak/liver, and SUVpeak/mediastinum. RESULTS: The metrics SUVmax, SUVpeak, SUVmax/liver, and SUVpeak/liver all proved to be sensitive for tumour differentiation (p ≤ 0.008); in contrast, SUVmax/mediastinum and SUVpeak/mediastinum revealed to be non-sensitive approaches. Correlation analyses showed inverse associations between reference region SUVs and SUVratios (p < 0.05). Multiple regression analyses demonstrated significant effects of factors as bodyweight and uptake time on reference region SUVs (p < 0.01), and thus indirectly on the corresponding SUVratios. CONCLUSIONS: In the paediatric population, the ability to differentiate between common tumours remarkably varies between SUV metrics. When using SUVratios, the choice of reference region is crucial. Factors potentially influencing reference region SUVs (and thus SUVratios) should be taken into account in order to avoid erroneous conclusions. When not possible, SUVmax and SUVpeak represent less complex, more robust alternatives.

Diagnostic accuracy of positron emission tomography for assessment of disease activity in large vessel vasculitis.

AIM: To determine the diagnostic yield of 18 F-fluorodeoxyglucose positron emission tomography (PET) in disease activity assessment of large vessel vasculitides (LVV). METHODS: Patients with LVV who had undergone PET (between 2004 and June 2010) or PET co-registered with computed tomography (PET/CT; since June 2010) were identified. Clinical disease activity was assessed using established scoring systems. PET images were reviewed by two blinded nuclear medicine physicians. Uptake of the aortic wall was compared to the liver uptake utilizing a visual 4-point score, with a vessel wall uptake similar or higher than liver uptake considered as active disease. Various target-to-background ratios were calculated. Receiver operator characteristics analysis was applied to determine the diagnostic accuracy of PET for detecting clinically active disease. Interobserver agreement of visual readings was measured with Cohen´s kappa. RESULTS: Eighty examinations in 62 patients were analyzed, with a mean time between diagnosis and PET of 106 ± 171 weeks. Fifty-seven cases were finally classified as clinically active and 23 cases as clinically inactive. With a cut-off value of 1.3, the aorta-to-liver ratio yielded a sensitivity and specificity of 84.2% and 82.6% (area under the curve 0.9). Overall, sensitivity and specificity of visual analysis were 68.4% and 91.3%, but sensitivity decreased to 54% in patients treated for more than 3 months. Interobserver agreement of visual rating was excellent (κ: 0.93). CONCLUSION: Positron emission tomography is specific and reliable in disease activity assessment of LVV, but lacks sensitivity for detecting active disease in patients under long-term immunosuppressive treatment.

CT fluoroscopy-guided percutaneous osteoplasty with or without radiofrequency ablation in the treatment of painful extraspinal and spinal bone metastases: technical outcome and complications in 29 patients.

PURPOSE: We aimed to assess the safety and technical outcome of computed tomography (CT) fluoroscopy-guided osteoplasty with or without prior percutaneous radiofrequency ablation (RFA) in patients with painful osteolyses. METHODS: We performed a retrospective analysis of 29 patients with painful extraspinal and spinal osteolyses (16 women, 13 men; 63.1±14.4 years) who underwent CT fluoroscopy-guided osteoplasty (10-20 mAs tube current) with or without RFA (26 and 14 lesions, respectively), in 33 consecutive procedures from 2002 to 2016. Technical success was defined as at least one complete RFA cycle and subsequent polymethyl metacrylate (PMMA) bone cement injection covering ≥75% of longest diameter of extraspinal osteolysis on axial plane or of distance between vertebral endplates. Procedure-related complications within 30 days and dose-length-product (DLP) were also evaluated. RESULTS: Osteolyses were located in the pelvis (acetabulum, n=10; iliac bone, n=4), spine (thoracic, n=6; lumbar, n=5; sacral, n=8), long bones (femur, n=3; tibia, n=1), sternum (n=2) and glenoid (n=1). Mean size of the treated osteolysis was 4.0±1.2 cm (range, 1.9-6.9 cm). Of 40 osteolyses, 31 (77.5%) abutted neighboring risk structures (spinal canal or neuroforamen, n=18; neighboring joint, n=11; other, n=8). Mean number of RFA electrode positions and complete ablation cycles was 1.5±0.9 and 2.1±1.7, respectively. Mean PMMA filling volume was 7.7±5.7 mL (range, 2-30 mL). Small asymptomatic PMMA leakages were observed in 15 lesions (37.5%). Mean total DLP was 850±653 mGy*cm. Six minor complications were observed, without any major complications. CONCLUSION: CT fluoroscopy-guided percutaneous osteoplasty with or without concomitant RFA for the treatment of painful extraspinal and spinal osteolyses can be performed with a low complication rate and high technical success.

Comparison of abdominal MRI with diffusion-weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas.

PURPOSE: The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and (68)Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas. METHODS: Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w + DW MRI, T2w + contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar's test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student's t test. RESULTS: Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23 = 61 %; observer 2: 15/23 = 65.2 %; p < 0.05) or CE T1w images (observer 1: 14/23 = 61 %; observer 2: 15/23 = 65.2 %; p < 0.05). Detection rates of pancreatic NET with PET/CT (both observers: 23/23 = 100 %) were statistically significantly higher than with MRI (p < 0.05). The mean ADC value of NET (1.02 ± 0.26 × 10(-3) mm(2)/s) was statistically significantly lower than that of normal pancreatic tissue (1.48 ± 0.39 × 10(-3) mm(2)/s). CONCLUSION: DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. (68)Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET.

Course of size and density of metastatic renal cell carcinoma lesions in the early follow-up of molecular targeted therapy.

OBJECTIVE: Imaging-based monitoring of molecular therapies in oncology remains a challenge. Molecular therapies might have more pronounced effects on lesion density than on lesion size. We analyzed changes in lesion diameter and density in patients with metastasized renal cell cancer (mRCC) in the early follow-up of targeted therapy and compared size-based measurements according to Response Evaluation Criteria in Solid Tumors (RECIST) with size- and density-based response evaluations according to the Choi criteria. PATIENTS AND METHODS: A total of 22 patients treated with sorafenib (800 mg/d) were retrospectively analyzed. Relative changes (in %) in the greatest diameter and density of defined neoplastic "target lesions" were determined 8 weeks and 1 year after start of therapy in relation to a pretherapeutic baseline investigation. Data were analyzed according to RECIST (ver. 1.0), and results were compared with the response assessment based on Choi. Median survival was determined for all subgroups according to Choi or RECIST at the 8-week and 1-year follow-up. RESULTS: Applying RECIST, 18 patients (82%) demonstrated stable disease (SD) 8 weeks after the start of targeted therapy, 3 patients (14%) partial response (PR), and 1 patient (4%) progressive disease (PD). Partial responders at 8 weeks had a median survival of 48 months. After 1 year, 59% of all patients still showed SD. Applying Choi, 15 patients (68%) showed PR 8 weeks after the start of therapy, 5 patients (23%) SD, and 2 patients (9%) PD. After 1 year, PR was still the predominant response group (64% of the patients). Partial responders after 8 weeks had a median survival of 18 months. CONCLUSION: Choi defined more patients as partial responders at early stages of therapy than RECIST, but this was not an effective selection for patients with prolonged median survival. Evaluation of a larger patient cohort will further clarify the role of combined size- and density-based follow-up strategies in targeted therapy of mRCC.

The phenotypic spectrum of neutral lipid storage myopathy due to mutations in the PNPLA2 gene.

Neutral lipid storage disease is caused by mutations in the CGI-58 or the PNPLA2 genes. Lipid storage can be detected in various cell types including blood granulocytes. While CGI-58 mutations are associated with Chanarin-Dorfman syndrome, a condition characterized by lipid storage and skin involvement (ichthyosis), mutations in the patatin-like phospholipase domain-containing protein 2 gene (PNPLA2) were reported with skeletal and cardiac muscle disease only. We describe clinical, myopathological, magnetic resonance imaging (MRI), and genetic findings of six patients carrying different recessive PNPLA2 mutations. Pulse-chase labeling of control and patient cells with supplementation of clenbuterol, salmeterol, and dexamethasone was performed in vitro. The patients share a recognizable phenotype with prominent shoulder girdle weakness and mild pelvic girdle and distal muscle weakness, with highly elevated creatine kinase (CK) and cardiomyopathy developing at later stages. Muscle histology invariably reveals massive accumulation of lipid droplets. New muscle or whole-body MRI techniques may assist diagnosis and may become a useful tool to quantify intramuscular lipid storage. Four novel and two previously reported mutations were detected, affecting different parts of the PNPLA2 gene. Activation of hormone-sensitive lipase by beta-adrenergic substances such as clenbuterol appears to bypass the enzymatic block in PNPLA2-deficient patient cells in vitro. PNPLA2 deficiency is a slowly progressive myopathy with onset around the third decade. Cardiac involvement is relatively common at a later stage. Muscle MRI may detect increased lipid in a characteristic distribution, which could be used for monitoring disease progression. Beta-adrenergic agents may be beneficial in improving triacylglycerol breakdown in patients with PNPLA2 mutations.

A novel mutation in the myotilin gene (MYOT) causes a severe form of limb girdle muscular dystrophy 1A (LGMD1A).

Here we describe a patient with limb girdle muscular dystrophy 1A (LGMD1A) due to a novel myotilin gene (MYOT) mutation with late onset, rapid progression, loss of ambulation and respiratory failure. The onset of weakness in proximal muscles and muscle MRI findings are clearly different from the pattern identified in myofibrillar myopathies (MFM) related to MYOT mutations. Moreover, there was very limited evidence of myofibrillar pathology in several muscle biopsies obtained during the disease course. We conclude, that MYOT mutations need to be considered as a rare cause of adult-onset, dominant LGMD without clear-cut MFM pathology.

Hydroxyapatite-coated pins versus titanium alloy pins in external fixation at the wrist: a controlled cohort study.

BACKGROUND: The purpose of this study was to analyze whether the prevalence of pin-related complications can be reduced by the use of hydroxyapatite (HA)-coated pins in external fixators applied for unstable wrist fractures. METHODS: Forty patients (160 pins) were randomized for standard uniplanar fixator treatment with the use of identically designed pins either composed of titanium-alloy (Ti6Al4V) (n = 20) or coated by HA (n = 20). Each pin site was clinically evaluated with regard to erythema, drainage, pain value, and radiologically assessed concerning loosening at T1 (mean, 9 days), T2 (mean, 43 days), and T3 (mean, 56 days). In case of pin-track complication, the patient was followed continuously. The need for antibiotics or additional surgery was documented. Bone mineral density was analyzed by Dual Energy X-ray Absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of a digital-torque-wrench. RESULTS: Two minor pin-track infections requiring oral antibiotics occurred in the HA-pin group (2.7%) (p > 0.05). The vast majority of clinical pin-site parameters were comparable in both groups. At the end of the fixator therapy, there were 16 loose pins (n(Ti6AL4V-group) = 10; n(HA-group) = 6). The rate of loose pins was correlated to patient's age (p < 0.05) but not to bone mineral density values or the occurrence of pin-site infection. Finally, no significant difference between the two groups was detected with regard to the prevalence of clinical relevant pin-site complications (p = 0.80). CONCLUSIONS: In external fixation of the wrist, the use of HA-coated pins yields no clinical advantages: there is a trend toward a superior pin-bone anchorage, but a tendency of increased susceptibility for minor pin-track infections.

Clinical benefit of hydroxyapatite-coated pins compared with stainless steel pins in external fixation at the wrist: a randomised prospective study.

BACKGROUND: The purpose of this study was to determine the clinical benefit of hydroxyapatite (HA)-coated pins compared with standard stainless steel pins in external fixators applied for unstable fractures of the distal radius. METHODS: A total of 40 patients (160 pins) with unstable wrist fractures were randomised for uniplanar fixator treatment with the use of identically designed, commercially available pins either composed of stainless steel (steel group) (n = 20) or coated by hydroxyapatite (HA group) (n = 20). Each pin site was clinically evaluated concerning erythema and grade of drainage as well as pain intensity (numeric rating scale (NRS) 0­10) and, additionally, radiological assessment was performed concerning pin-loosening/infection as well as fracture healing at T1 (Ø18 days), T2 (Ø44 days) and T3 (Ø65 days). In case of pintrack complication, the patient was followed continuously. The need for intensified pin-site care, oral or intravenous antibiotic medication, re-admission for additional surgery and premature fixator removal was documented. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of an electronic torque wrench. RESULTS: Two pin-track infections requiring daily pin-site care and oral antibiotics occurred in the HA group (2.6%) compared with four in the steel group (5.3%) (p = 0.601) and although a trend towards a superior performance of HA pins was detectable, the majority of clinical pin-site-parameters were comparable in both groups. At the end of the fixator therapy, the HA group showed a non-significant lower rate of loose pins (n(steel group) = 9; n(HA group) = 6; p = 0.864) and both hydroxyapatite-coated pins showed at the radius a significantly stronger pin-bone bonding measured by the torque wrench (p(proximal radius pin) = 0.007; p(distal radius pin) = 0.031). Except for elderly patients of the steel group (p = 0.018), all demographic-, health- and injury-related data including BMD were not correlated to any type of pin-site complication in both groups (p > 0.05). Since all fracture healed uneventfully without any type of additional surgery, the number of patients suffering clinically relevant pin-related complications showed no significant difference between both groups (p = 0.707). CONCLUSIONS: The use of HA-coated pins compared with standard stainless-steel pins in external fixation for unstable wrist fractures yields only a trend towards a superior clinical outcome.

Facioscapulohumeral muscular dystrophy presenting with unusual phenotypes and atypical morphological features of vacuolar myopathy.

Facioscapulohumeral muscular dystrophy (FSHD) is the third most common muscular dystrophy and usually follows an autosomal dominant trait. Clinically, FSHD affects facial muscles and proximal upper limb and girdle muscles, but may present with variable clinical phenotypes even within the same family. Most genetically confirmed FSHD patients exhibit unspecific morphological signs of a degenerative myopathy. We report on five unrelated patients who carried the pathogenic FSHD mutation on chromosome 4q35. Muscle biopsies revealed numerous rimmed vacuoles and filamentous cytoplasmic inclusions in all cases. Clinically, the patients suffered from weakness and atrophy predominantly of the lower limb muscles. In conclusion, we suggest considering FSHD in the differential diagnosis of adult-onset distal myopathies with rimmed vacuoles.

The p.G154S mutation of the alpha-B crystallin gene (CRYAB) causes late-onset distal myopathy.

Mutations in alpha-B crystallin gene (CRYAB) have been described to cause congenital cataracts, dilated cardiomyopathy and myofibrillar myopathy. For skeletal myopathy, only three different mutations have been reported within the last decade. Here we describe for the first time the missense mutation p.Gly154Ser to be associated with a late-onset distal vacuolar myopathy with protein aggregates without respiratory or cardiac dysfunction, and without significant cataracts. The mutation affects a residue in a highly preserved domain of alpha-B crystallin and has been identified earlier in patients with isolated cardiomyopathy.

Lower limb radiology of distal myopathy due to the S60F myotilin mutation.

Distal myopathies are a clinically and genetically heterogenous group of disorders in which the distal limb musculature is selectively or disproportionately affected. Precisely defining specific categories is a challenge because of overlapping clinical phenotypes, making it difficult to decide which of the many known causative genes to screen in individual cases. In this study we define the distinguishing magnetic resonance imaging findings in myotilin myopathy by studying 8 genealogically unrelated cases due to the same point mutation in TTID. Proximally, the vastii, biceps femoris and semimembranosus were involved with sparing of gracilis and sartorius. Distally, soleus, gastrocnemius, tibialis anterior, extensor hallicus and extensor digitorum were involved. This pattern contrasts with other distal myopathies and provides further support for the role of imaging in the clinical investigation of muscle disease.

Involvement patterns in myotilinopathy and desminopathy detected by a novel neuromuscular whole-body MRI protocol.

Whole-body MRI (WB-MRI) has been successfully applied for oncologic and cardiovascular diagnostics, whereas imaging in myopathies usually employs dedicated protocols restricted to areas of specific interest. In this study, we propose a comprehensive neuromuscular WB-MRI protocol. Eighteen patients with degenerative and inflammatory muscle diseases were included. Whole-body imaging was performed on a 1.5-T MR system using parallel imaging. Examination time was 41:26 min. Coronal and axial T1-weighted and coronal short tau inversion recovery (STIR) sequences of the whole body were acquired. Images were analysed by two radiologists. With this protocol we could detect characteristic involvement patterns in different myofibrillar myopathies (MFMs): Patients with myotilinopathy showed frequent involvement of the rhomboid muscles (4/5), the erector spinae (5/5), the biceps femoris and the semimembranosus (5/5), while the semitendinosus was relatively spared (2/5). In contrast, in desminopathy patients the ilipsoas (3/4), the sartorius, (3/4), the gracilis (3/4) and the semitendinosus (3/4) were frequently involved, while the semimembranosus was spared (1/4). As shown for MFMs, WB-MRI is an appropriate modality to detect fatty infiltration and oedema in skeletal muscles. WB-MRI could be more useful than dedicated examinations for differential diagnosis, muscle biopsy planning and noninvasive follow-up examinations.

T-cell response to p53 tumor-associated antigen in patients with colorectal carcinoma.

Despite the radical surgical resection performed in patients with colorectal carcinoma, there is a high rate of tumor recurrence. Over an observation period of 3 years, 18% of the patients in our collective suffered a tumor relapse with local or distinct metastases after initial R0-resection. Some evidence suggests that this may be due to suppression of anti-tumor responses, a phenomenon that might be attributed to regulatory T cells. The aim of our study was to investigate the tumor-specific immune response depending on the UICC stage of patients with colorectal cancer. The cellular immune responses against defined antigens that are overexpressed in most of the patients with colorectal cancer were characterized. For this purpose, the tumor suppressor gene, p53, was chosen as the tumor-associated antigen that exhibits mutations and overexpression in up to 60% of colorectal carcinoma. We observed that p53 induced both IFN-gamma and IL-10 secretion. The predominance of IL-10 production indicated that regulatory T cells directly participate in modulating the anti-tumor immune response. IL-10 levels in the blood as well as the expression of regulatory T-cell specific genes at the tumor site correlate with the UICC stage of the disease. These results may provide an explanation for the poor prognosis and increased recurrence rate in patients with advanced carcinoma.