Comparison of liver SUV using unenhanced CT versus contrast-enhanced CT for attenuation correction in (18)F-FDG PET/CT.

AIM: The aim of the study was to compare standardized uptake values (SUVs) in liver tissue obtained using whole-body unenhanced low-dose computed tomography (CT) with those obtained using contrast-enhanced high-dose CT for PET attenuation correction in PET/CT scanning. MATERIALS AND METHODS: Ten patients scheduled for (18)F-FDG PET and contrast-enhanced CT of the abdomen were included in this study. PET data were corrected for attenuation using both unenhanced low-dose CT images and contrast-enhanced high-dose CT images. Differences in SUV(mean) and SUV(max) were compared in three liver regions. RESULTS: The average SUV(mean) and SUV(max) of all regions were 2.43 and 2.91 g/cm in the unenhanced data set and 2.53 and 3.17 g/cm in the enhanced data set, respectively. CONCLUSION: SUV(mean) and SUV(max) were significantly elevated in liver tissue when using PET images corrected for attenuation with contrast-enhanced high-dose CT compared with PET images corrected with unenhanced low-dose CT. Although the differences may not be relevant in daily clinical practice, unenhanced and contrast-enhanced CT should not be selected randomly for attenuation correction if exact quantitative results are required.

Genome-scale discovery of DNA-methylation biomarkers for blood-based detection of colorectal cancer.

BACKGROUND: There is an increasing demand for accurate biomarkers for early non-invasive colorectal cancer detection. We employed a genome-scale marker discovery method to identify and verify candidate DNA methylation biomarkers for blood-based detection of colorectal cancer. METHODOLOGY/PRINCIPAL FINDINGS: We used DNA methylation data from 711 colorectal tumors, 53 matched adjacent-normal colonic tissue samples, 286 healthy blood samples and 4,201 tumor samples of 15 different cancer types. DNA methylation data were generated by the Illumina Infinium HumanMethylation27 and the HumanMethylation450 platforms, which determine the methylation status of 27,578 and 482,421 CpG sites respectively. We first performed a multistep marker selection to identify candidate markers with high methylation across all colorectal tumors while harboring low methylation in healthy samples and other cancer types. We then used pre-therapeutic plasma and serum samples from 107 colorectal cancer patients and 98 controls without colorectal cancer, confirmed by colonoscopy, to verify candidate markers. We selected two markers for further evaluation: methylated THBD (THBD-M) and methylated C9orf50 (C9orf50-M). When tested on clinical plasma and serum samples these markers outperformed carcinoembryonic antigen (CEA) serum measurement and resulted in a high sensitive and specific test performance for early colorectal cancer detection. CONCLUSIONS/SIGNIFICANCE: Our systematic marker discovery and verification study for blood-based DNA methylation markers resulted in two novel colorectal cancer biomarkers, THBD-M and C9orf50-M. THBD-M in particular showed promising performance in clinical samples, justifying its further optimization and clinical testing.

Hb Boskoop [HBA2c.112C>T p.Pro38Ser]: a new α2 chain variant observed in a Morrocan family.

We describe a new nondeletional α-thalassemia (α-thal) determinant found in a Moroccan infant and in two members of his family. The new mutation generates an abnormal hemoglobin (Hb) as a consequence of a Pro→Ser amino acid substitution at codon 37 (old nomenclature) of the α2 gene. The new Hb variant is barely separable on high performance liquid chromatography (HPLC) but the expression of the α chain mutant measured on reversed phase chromatography is one-third of that expected from a stable α2 variant, which explains the mild α-thal phenotype observed in the carriers. As shown for other mutations described in our laboratory (i.e., Hb Gouda), this variant could also be common in the North African population, overlooked because of the mild phenotype and silent behavior on HPLC. Nevertheless, these silent variants could generate intermediate Hb H diseases in association with Mediterranean α(0)-thal deletion defect.

Hb St. Jozef, A Val-->Leu N-terminal mutation leading to retention of the methionine, and partial acetylation found in the globin gene in Cis with a -alpha3.7 thalassemia deletion.

We report a new hemoglobin (Hb) variant found in a 6-year-old girl of Moroccan origin, living in the Dutch city of Gouda. The child was referred because of microcytic and hypochromic parameters. A normal zinc protoporphyirin (ZPP) value excluded iron deficiency and gap-polymerase chain reaction (gap-PCR) revealed a heterozygosity for the common -alpha(3.7) thalassemia deletion, partially justifying the hematological picture. The Hb pattern on alkaline electrophoresis and capillary electrophoresis was normal, while a fraction of 9% preceding the Hb A peak, remained visible on different high performance liquid chromatography (HPLC) devices. This fraction, located in front of the Hb A peak, is usually considered as a Hb A derivate that becomes more expressed in older samples. However, the sample was freshly collected and the peak unusually evident. Therefore, direct sequencing of the alpha-globin genes was performed revealing a GTG-->CTG transversion at codon 1 of the alpha1-globin gene or of the hybrid gene. This point mutation induces a single amino acid substitution from valine to leucine. Electrospray-mass spectrometry (ES-MS) analysis revealed, in addition to this substitution, that the N-terminal methionine was retained and that about 20% of the variant was acetylated. As expected for an association with a -alpha(3.7)-thalassemia (thal) deletion, the non acetylated and acetylated abnormal alpha chain amounted to 32% of the total alpha chains. Family studies revealed that the mutated codon was located in cis of the deletion.

The rare Hb Showa-Yakushiji [beta110(G12)Leu-->Pro, CTG-->CCG] in combination with an alpha gene triplication found in a Dutch patient during her first pregnancy examination.

We report a semi dominant beta-thalassemia (thal) phenotype caused by the rare Hb Showa-Yakushiji [beta110(G12)Leu-->Pro, CTG-->CCG] mutation in combination with an alpha gene triplication. This combination of two rare mutations was observed during hemoglobinopathy carrier diagnostics in a 26-year-old Dutch female at 9 weeks gestation, at the first pregnancy examination in the midwives practice. The partner was promptly examined and no abnormalities were found. The beta-thal trait was diagnosed by a standard high performance liquid chromatography (HPLC) procedure showing a normal separation but an elevated Hb A(2) level of 5.9% in the presence of pronounced hypochromic microcytic parameters and mild chronic hemolysis. Direct sequencing of the beta-globin genes was subsequently performed revealing a CTG-->CCG transition at codon 110. This rare mutation was previously described as two independent events in a few Japanese and Indian individuals. The mutation induces a Leu-->Pro substitution and the gene product is highly unstable. Gap-polymerase chain reaction (gap-PCR) revealed a heterozygosity for the alpha gene triplication as well. The excess of alpha-globin chains contributed only marginally to the hematological abnormalities of the patient and did not aggravate the phenotype to an intermediate level.

Hb Bleuland [alpha108(G15)Thr-->Asn, ACC-->AAC (alpha2)]: a new abnormal hemoglobin associated with a mild alpha-thalassemia phenotype.

We report a new structural defect of the alpha2-globin chain, not detectable on high performance liquid chromatography (HPLC) or electrophoresis, characterized in a 12-year-old boy of Surinamese-Hindustani origin. The child was suspected to be a carrier of alpha-thalassemia (thal) because of microcytic hypochromic parameters in the absence of iron depletion. Gap-polymerase chain reaction (gap-PCR) revealed only normal fragments in the proband, and the pattern of a -alpha4.2 (leftward) deletion in his father and sister. Direct sequencing of the alpha-globin genes revealed an ACC-->AAC transversion at codon 108 of the alpha2-globin gene in the proband, in his mother and in a younger sister. The new mutation predicts a Thr -->Asn amino acid substitution at the corresponding residue. Threonine, a covalent binder with an R-active OH group, situated in the G helix of the alpha-globin chain, is involved in alpha1beta1 contacts. Asparagine, being an equally covalent binder but with a different R-active H2N-C=O group, could make the mutated chain less suitable for tetramer cooperation. Alternatively, an absent or reduced interaction with the alpha hemoglobin (Hb) stabilizing protein (AHSP) could lead to loss of alpha chains. Hb Bleuland is the first mutation described at codon 108 and is therefore interesting in regard to the possible effects and genetic risk. The nearest variant, Hb Suan-Dok [alpha109(G16)Leu -->Arg, CTG-->CGG (alpha2)] was originally observed in a Thai patient affected with Hb H, in combination with an alpha0-thal allele. The same Hb Suan-Dok mutation, recently described in our laboratory in a carrier of African ancestry, was also not detectable as a protein and presented with an alpha-thal phenotype similar to Hb Bleuland.

Biodistribution and imaging of FDG in rats with LS174T carcinoma xenografts and focal Escherichia coli infection.

OBJECTIVE: The aim of this study was to compare the dynamic distribution of fluorodeoxyglucose (FDG) in malignant and in infectious lesions. METHODS: The dynamic distribution of FDG was studied in Rowett nude (RNU) rats with a LS174T carcinoma xenograft in the left front leg and an Escherichia coli-induced focal infection in the right front leg. In 5 rats, dynamic FDG-PET was performed (27 frames of 6-15 minutes) up to 4 hours after injection of 11 MBq 18FDG. The mean FDG uptake (SUV) was calculated and plotted by using a region of interest (ROI) centered over both lesions. In groups of 6 rats, the biodistribution of FDG was determined by counting dissected tissues at 1, 2, 3, and 4 hours after an injection of 11 MBq FDG. Means +/- the standard error of the mean (SEM) were calculated. RESULTS: Dynamic positron emission tomography (PET) visualized both the tumor and the infection. The ROI analysis showed that FDG uptake in the infections was faster and higher, as compared to the tumor lesions. FDG uptake in the tumor reached a standardized uptake value (SUV) of 0.8 +/- 0.3 at 60 minutes and in the infectious lesions a SUV of 1.6 +/- 0.2 at 45 minutes, both remaining constant until 4 hours postinjection (p.i.). In the biodistribution study with ex vivo tissue counting, FDG had accumulated up to 1.1 +/- 0.1 %ID/g and 0.8 +/- 0.1 %ID/g at 1 hour in the tumor and infection, respectively, and remained constant until 4 hours for both lesions without significantly different wash-out from the 2 lesions. The tumor/blood and abscess/ blood ratios increased with time to 57 +/- 17 and 48 +/- 14, respectively. CONCLUSION: Although in this model differences in absolute FDG uptake and initial kinetics between tumor and infection were observed, the wash-out rate of FDG from the lesions was similar over time. The retention of FDG in the inflammatory lesion indicated that dual time-point imaging does not necessarily resolve diagnostic pitfalls for FDG-PET in oncology in order to discriminate between malignant tumorous and benign infectious lesions.

Influence of blood glucose level, age and fasting period on non-pathological FDG uptake in heart and gut.

PURPOSE: Increased, non-pathological FDG uptake in myocardium, stomach and bowel is frequently observed while performing clinical positron emission tomography (PET) studies. This "physiological" increased FDG uptake is not related to (oncological) disease and is unwanted since it may interfere with correct image reading. We evaluated the role of several patient-related factors that may have an influence on this phenomenon. METHODS: One hundred and seventy-five non-diabetic patients with malignant diseases, referred to our department for routine whole-body FDG-PET, were retrospectively evaluated. Age, blood glucose levels and duration of the fasting period were recorded. FDG uptake in myocardium, bowel and stomach was visually graded. RESULTS: Statistical analysis showed that increased FDG uptake in myocardium, bowel and stomach was not significantly correlated to blood glucose level, age or duration of fasting. Most patients who underwent repeated PET scans (92 scans in 25 patients), showed no or minor changes in uptake in bowel and stomach on the consecutive scans, while myocardial uptake was more variable. CONCLUSION: Age, fasting period and blood glucose levels did not influence physiological uptake. However, there seemed to be a patient-specific pattern for stomach and bowel uptake.

Hb Buffalo [alpha89(FG1)His-->Gln (alpha1)], observed solely and in the presence of an Hb S [beta6(A3)Glu-->Val] heterozygosity.

The hemoglobin (Hb) pattern of a 32-year-old Somali male living in The Netherlands, during routine diabetes mellitus monitoring, showed two more peaks in addition to the characteristic heterozygous Hb A/S pattern. A major peak of 15% faster than Hb A, and a minor one of 10.8%, overlapping Hb A2 and the glycated Hb S1c fraction were present. The patient was not anemic or microcytic but had a low haptoglobin level, possibly indicating a slightly elevated red blood cell (RBC) turnover. Hb S was confirmed by a sickle test and at the DNA level. The DNA sequence of the alpha1 gene revealed a C-->G transversion at position 89, changing the local positively charged histidine to a neutral glutamine. This mutant has been previously described in a Yemenite woman and two apparently unrelated Somali males. Our case is the first showing Hb Buffalo in combination with Hb S and a G6PD deficiency, and is again observed in a Somali. No functional abnormalities associated with mutations at this amino acid residue are reported in the literature. Also, in this case no sign of any hematological abnormalities that could not be explained by the Hb S heterozygosity G6PD deficiency was found. The abnormal alpha chain is expressed at the expected rate and without thalassemic effect or instability. The mutated alpha chain seems to associate with a slight preference to the beta(A) (15%) rather than with the beta(S) counterpart. The sum of both Hb A(Buffalo) and Hb S(Buffalo) results in about 19-20% of total Hb. This figure is in agreement with a stable mutant of the alpha1 gene.

A new Hb evanston allele [alpha14(A12)Trp --> Arg] found solely, and in the presence of common alpha-thalassemia deletions, in three independent Asian cases.

Hb Evanston [alpha14(A12)Trp --> Arg] is considered to be a rare alpha chain mutant, and was originally observed in two Black families in 1982, inducing a mild Hb H disease phenotype in a homozygous state for the -alpha3.7 deletion ( -alpha(Evanston)/ -alpha). The mutant, evidently linked with one of the two -alpha3.7 thalassemia (thal) alleles, was considered to be unstable and rapidly proteolyzed. We describe Hb Evanston in three new independent Asian cases, all induced by a TGG --> CGG transition. In all cases the mutation is linked to the alpha1-globin gene, either on a wild type allele or in linkage with the common -alpha3.7 and -alpha4.2 deletion alleles. The beta/alpha ratio was balanced in the presence of the mutation only, and accordingly unbalanced in co-inheritance with the deletion defects. Although a second independent mutation event on a -alpha3.7 or a -alpha4.2 deletion allele could not be excluded, we conclude that at least one independent Hb Evanston mutation has occurred on a wild type allele in the Asian populations. Unstable Hb tetramers tend to degrade and disappear during purification. Both Hb Evanston tetramers, formed in combination with normal beta and delta chains, remain perfectly stable after extensive purification and concentration steps, suggesting an early posttranslational thalassemic effect, probably at the dimer/tetramer affinity level.

Hb Groene Hart: a new Pro-->Ser amino acid substitution at position 119 of the alpha1-globin chain is associated with a mild alpha-thalassemia phenotype.

Alpha-Thalassemia (thal) is generally considered to be an expression defect caused mostly by deletions silencing one or more alpha-globin genes. Although nondeletional alpha-thalassemia is considered rare, in our laboratory we frequently observe alpha-thal phenotypes induced by point mutations. We report a new point mutation generating an abnormal hemoglobin (Hb) associated with a mild alpha-thal phenotype in two members of a Moroccan family, who presented with mild but persistent microcytic hypochromic parameters and a balanced beta/alpha synthetic ratio. All attempts to separate an abnormal native or denatured fraction were unsuccessful using electrophoresis, isoelectrofocusing (IEE), ion exchange and reversed phase high performance liquid chromatography (HPLC), denaturing polyacrylamide gel electrophoresis (PAGE), and electrospray mass spectrometry (ES/MS). The anomalous protein was only predictable by DNA analysis. The mutated gene product, not separable with any of the techniques used, could be a monomer unsuitable for tetramer formation, which is proteolyzed at an early stage. Alternatively, this mutation could perhaps lead to an abnormal splicing. The CCTCT sequence generated by the mutant, not found in the translated region of the gene, but normally present at the end of the IVS-II, could induce a possible exon skipping. This mutant could generate a mild or a critical Hb H disease in combination with one of the common alpha0-thal deletion defects.