Imaging of acute superior mesenteric artery embolus using spectral CT in a canine model

Objective:

To explore the diagnostic value of single-source dual-energy spectral CT (sDECT) imaging in an acute superior mesenteric artery embolus (SMAE) canine model.

Methods:

Pre-contrast and double-phase contrast-enhanced sDECT were performed before and after embolization in eight SMAE dog models. Monochromatic images of embolized intestine with the best contrast-to-noise ratio (CNR) were obtained and compared with the polychromatic images. CT parameters including attenuation value, iodine content, water content and thickness of the embolized intestinal segments were obtained, and normalized difference in iodine concentration (NDIC) was calculated.

Results:

The CNR in pre-contrast, arterial phase and portal venous phase at 4 h after embolization was 1.11 ± 1.23, 13.50 ± 1.54 and 10.63 ± 3.75, respectively, significantly higher than those of the polychromatic images (p < 0.05). The iodine-based images clearly revealed the embolized intestinal segments, which were highly consistent with the gross findings. The difference in attenuation values between the embolization area and non-embolization area in the monochromatic images was 105.06 ± 35.35 HU, higher than that in the polychromatic images (p < 0.001). The attenuation values and NDIC were significantly decreased at 2 h after embolization, relatively increased at 4 h and gradually decreased at 6 and 8 h. The changing pattern of thickness was similar to that of NDIC over time after embolization.

Conclusion:

sDECT can provide the optimal monochromatic images and allow increased detection rates of lesions. sDECT is a very promising tool for quantitative diagnosis of SMAE.

Advances in knowledge:

Our research provides more quantitative parameters for the assessment of SMAE by sDECT.     

Association of pericardial fat volume with coronary atherosclerotic disease assessed by CT angiography

Objective:

To investigate the association of pericardial fat volume (PFV) with coronary artery disease (CAD) in patients with intermediate pre-test probability of ischaemic heart disease assessed by coronary CT angiography.

Methods:

From a total of 115 consecutive Iraqi patients who underwent 64-multislice multidetector CT angiography examinations, only 74 patients (females, 38% and males, 68%) with a mean age of 54 ± 8 years were found to be eligible for statistical analysis. The patients were divided into two groups according to the median value of PFV (above and below 100 ml).

Results:

The median value of PFV in our study was 100 ml (range, 17–319 ml). A significant association was observed between high PFV and significant coronary artery stenosis (p = 0.005), between high PFV and significant left circumflex stenosis (p = 0.021) and between high PFV and the presence of coronary plaque (p = 0.005). Whereas there was no significant correlation between high PFV and coronary calcium score (p = 0.188), between high PFV and number of diseased coronary vessels (p > 0.3), and between high PFV and body weight and body mass index.

Conclusion:

Increased PFV is strongly associated with the presence and severity of CAD.

Advances in knowledge:

Our study highlights the role of pericardial fat as an emerging biomarker in cardiovascular risk assessment and supports its association with the magnitude of CAD.Pericardial fat is an adipose tissue surrounding the heart, with anatomic proximity to the epicardial coronary arteries. Several studies^1–5 show growing evidence that pericardial adipose tissue may be associated with increased left ventricular mass, metabolic syndrome, endothelial dysfunction, insulin resistance and the presence of coronary artery disease (CAD) via local secretion of numerous pro-inflammatory hormones and cytokines.Coronary CT angiography is a non-invasive method that has been used for cardiovascular risk stratification based on the presence and severity of coronary calcium and atherosclerotic plaque with a reported sensitivity of 94–95% and specificity of 82%. Pericardial fat volume (PFV) can be assessed by direct measurement that depends on the detection of the thin pericardium or as a component of heart-level thoracic fat volume.^6,7Pericardial fat has been found to have a higher lipolysis and lipogenesis activity than that of other fat tissues with a strong correlation between PFV and triglyceride concentration in the myocardium.⁸Furthermore, recent data have shown that PFV assessed by CT angiography is significantly associated with severe coronary stenosis, plaque burden even in asymptomatic individuals, high-risk plaque features and an increased risk of future cardiac events.^9–11The aim of this study was to investigate the association of PFV with CAD, cardiac risk factors and calcium scoring index in patients with an intermediate pre-test probability of ischaemic heart disease assessed by coronary CT angiography.     

The prevalence and clinical importance of incidental soft-tissue findings in cervical CT scans of trauma population

Objectives:

To define the age-related prevalence of incidental soft-tissue findings in cervical CT scans of a trauma population and to investigate their clinical importance.

Methods:

The original diagnostic radiology reports and the CT images of the 357 patients with cervical trauma were retrospectively evaluated. Incidental soft-tissue findings were investigated. All findings were grouped according to age. The findings were classified based on their clinical importance into three categories: Category 1: no clinical importance, Category 2: possible clinical importance requiring further investigation and Category 3: obvious clinical importance. In addition, the medical records of the patients were investigated. The follow-up ratio of the pathologies mentioned in the original radiology report was recorded.

Results:

The most frequently encountered findings in Categories 2 and 3 were carotid artery calcification (n = 89, 24.9%) and tonsillolith (n = 115, 32.2%), respectively. The reporting ratio in the original reports of Categories 1, 2 and 3 findings was 1.1% (n = 4), 9% (n = 27) and 34.5% (n = 64), respectively. No further investigations and follow-up was accomplished for Category 1 lesions, whereas 11.1% of Category 2 and 35.9% of Category 3 lesions were subjected to further investigations and follow-up.

Conclusions:

The cervical CT scans of trauma patients reveal many clinically important soft-tissue incidental findings. Cervical region incidental findings may be followed up on an outpatient basis, rarely being of life-threatening value. The ratio of reporting and follow-up of incidental findings increases parallel to the clinical importance of the lesions.     

Visually stratified CT honeycombing as a survival predictor in combined pulmonary fibrosis and emphysema

Objective:

To determine whether visually stratified CT findings and pulmonary function variables are helpful in predicting mortality in patients with combined pulmonary fibrosis and emphysema (CPFE).

Methods:

We retrospectively identified 113 patients with CPFE who underwent high-resolution CT between January 2004 and December 2009. The extent of emphysema and fibrosis on CT was visually assessed using a 6- or 5-point scale, respectively. Univariate and multivariate Cox proportional regression analyses were performed to determine the prognostic value of visually stratified CT findings and pulmonary function variables in patients with CPFE. Differences in 5-year survival rates in patients with CPFE according to the extent of honeycombing were calculated using Kaplan–Meier analysis.

Results:

An increase in the extent of visually stratified honeycombing on CT [hazard ratio (HR), 1.95; p = 0.018; 95% confidence interval (CI), 1.12–3.39] and reduced diffusing capacity of lung for carbon monoxide (DLCO) (HR, 0.97; p = 0.017; 95% CI, 0.94–0.99) were independently associated with increased mortality. In patients with CPFE, the 5-year survival rate was 78.5% for <5% honeycombing, 55.7% for 5–25% honeycombing, 32% for 26–50% honeycombing and 33.3% for >50% honeycombing on CT.

Conclusion:

The >50% honeycombing on CT and reduced DLCO are important prognostic factors in CPFE.

Advances in knowledge:

Visual estimation of honeycombing extent on CT can help in the prediction of prognosis in CPFE.     

Prevalence of palatine tonsilloliths: a retrospective study on 150 consecutive CT examinations

Objectives:

To evaluate the prevalence of palatine tonsilloliths.

Methods:

150 consecutive CT examinations (75 males and 75 females) were read.

Results:

Tonsilloliths were found in 37 patients (24.6%; confidence interval 17.7–31.6%), of which 18 (48%) had a bilateral location. No influence of sex or age was observed (p = 0.37 and p = 0.57, respectively). 26 patients (70%) had more than 1 concretion. The largest tonsillolith was 7 mm. None of the tonsilloliths found were involved in the reason for prescribing the CT. The radiographic density of the tonsilloliths was between 216 and 2959 HU.

Conclusions:

Palatine tonsilloliths could affect approximately one-quarter of the population. This prevalence is likely to be underestimated in daily clinical practice because small concretions do not result in any functional impairment and are not visible on orthopantomographs.     

Correlation between anthropometric parameters and acute skin toxicity in breast cancer radiotherapy patients: a pilot assessment study

Objective:

The objective of the present study was to identify acute skin toxicity risk factors linked to the anthropometric characteristics of patients with breast cancer treated with radiation therapy.

Methods:

Consecutive patients with breast cancer were enrolled after breast-conserving surgery and before radiotherapy course. Acute skin toxicity was assessed weekly during the 7 weeks of radiotherapy with the International Classification from National Cancer Institute. Grade 2 defined acute skin toxicity. Patient characteristics and anthropometric measurements were collected.

Results:

54 patients were enrolled in 2013. Eight patients (14.8%) had grade ≥2 toxicity. The average weight and chest size were 65.5 kg and 93.6 cm, respectively. Bra cup size is significantly associated with a risk of grade 2 dermatitis [odds ratio (OR) 3.46, 95% confidence interval (CI) (1.29–11.92), p = 0.02]. Anthropometric breast fat mass measurements, such as thickness of left [OR 2.72, 95% CI (1.08–8.26), p = 0.04] and right [OR 2.45, 95% CI (0.99–7.27), p = 0.05] axillary fat, are correlated with an increased risk. Distance between the pectoral muscle and nipple is a reproducible measurement of breast size and is associated with acute skin toxicity with significant tendency (OR = 2.21, 95% CI (0.97–5.98), p = 0.07).

Conclusion:

Breast size and its different anthropometric measurements (thickness of left and right axillary fat, nipple-to-pectoral muscle distance) are correlated with the risk of skin toxicity.

Advances in knowledge:

The present article analyses several characteristics and anthropomorphic measurements of breast in order to assess breast size. A standardized and reproducible protocol to measure breast volume is described.     

Trabecular bone histomorphometric measurements and contrast-to-noise ratio in CBCT

Objectives:

The aim of this study was to evaluate how imaging parameters at clinical dental CBCT affect the accuracy in quantifying trabecular bone structures, contrast-to-noise ratio (CNR) and radiation dose.

Methods:

15 radius samples were examined using CBCT (Accuitomo FPD; J. Morita Mfg., Kyoto, Japan). Nine imaging protocols were used, differing in current, voltage, rotation degree, voxel size, imaging area and rotation time. Radiation doses were measured using a kerma area product-meter. After segmentation, six bone structure parameters and CNRs were quantified. Micro-CT (μCT) images with an isotropic resolution of 20 μm were used as a gold standard.

Results:

Structure parameters obtained by CBCT were strongly correlated to those by μCT, with correlation coefficients >0.90 for all studied parameters. Bone volume and trabecular thickness were not affected by changes in imaging parameters. Increased tube current from 5 to 8 mA, decreased isotropic voxel size from 125 to 80 μm and decreased rotation angle from 360° to 180° affected correlations for trabecular termini negatively. Decreasing rotation degree also weakened correlations for trabecular separation and trabecular number at 80 μm voxel size. Changes in the rotation degree and tube current affected CNR significantly. The radiation dose varied between 269 and 1153 mGy cm².

Conclusions:

Trabecular bone structure can be accurately quantified by clinical dental CBCT in vitro, and the obtained structure parameters are strongly related to those obtained by μCT. A fair CNR and strong correlations can be obtained with a low radiation dose, indicating the possibility for monitoring trabecular bone structure also in vivo.     

Comparative study of CT appearances in mucinous tubular and spindle cell carcinoma and collecting duct carcinoma of the kidney

Objective:

To characterize the multidetector CT (MDCT) imaging characteristics of mucinous tubular and spindle cell carcinoma (MTSCC) and collecting duct carcinoma (CDC) of the kidney.

Methods:

21 patients with MTSCC and 18 patients with CDC were studied retrospectively. MDCT was undertaken to investigate differences in tumour characteristics.

Results:

Five patients with MTSCC had calcifications as did nine patients with CDC (p = 0.108). In three patients with MTSCC and four patients with CDC, the tumours had a clear boundary (p = 0.682). No patient with MTSCC had retroperitoneal lymph node metastasis as did five patients with CDC (p = 0.015). 16 patients with MTSCC showed homogeneous enhancement, whereas 11 patients with CDC showed heterogeneous enhancement (p = 0.025). The attenuation value of CDC tumours was greater than that of MTSCC and normal renal parenchyma on an unenhanced CT (p = 0.027). MTSCC and CDC tumour enhancement was less than the normal renal cortex and medulla in all phases (p < 0.001). Tumour enhancement was greater for CDC than that for MTSCC in all phases (p = 0.011, p = 0.006 and p = 0.052).

Conclusion:

Unenhanced and dynamic MDCT may aid in diagnosis and differentiation of MTSCC and CDC of the kidney.

Advances in knowledge:

This is the first series evaluating the imaging findings of MTSCC and CDC of which we are aware, and identification of such findings may improve diagnosis of these two rare tumours.     

The Clinical Usefulness of 18F-FDG PET/CT in Patients with Systemic Autoimmune Disease

Purpose

Individuals with systemic autoimmune disease have an increased susceptibility to both inflammation and malignancy. The aim of this study was to evaluate the clinical usefulness of ¹⁸F-FDG PET/CT in patients with systemic autoimmune disease.

Methods

Forty patients diagnosed with systemic autoimmune disease were enrolled. Diagnostic accuracy of FDG PET/CT for detecting malignancy was assessed. FDG PET/CT findings, including maximum standardized uptake (SUVmax) of lymphadenopathy (LAP), liver, bone marrow, spleen, joint and muscles, were considered for the characterization of LAPs.

Results

FDG PET/CT could detect metabolically activated lesions in 36 out of 40 patients (90%) including inflammatory lesions in 28 out of 32 patients (88%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG PET/CT for the detection of malignancy were 100, 67, 70, 25, and 100%, respectively. Multiple LAPs were found in 25 of 40 patients (63%), and comprised three malignancies, four cases of tuberculosis, and 18 reactive changes. A SUVmax ratio of bone marrow to liver below 0.78 could distinguish malignancy from tuberculosis + reactive change (AUC = 1.000, sensitivity: 100%, specificity: 100%). The SUVmax ratio of spleen to liver in the reactive group was also significantly higher than that in the malignancy group (P = 0.014). SUVmax of LAP in the TB group was significantly higher than that in the reactive group (P = 0.040).

Conclusions

PET/CT is useful in detecting and differentiating inflammation and malignancy in patients with systemic autoimmune disease. Frequent false-positive interpretations can be minimized by consideration of FDG uptake in bone marrow and spleen.     

Enamel pearls in permanent dentition: case report and micro-CT evaluation

Objectives:

To investigate the frequency, position, number and morphology of enamel pearls (EPs) using micro-CT (µCT) and to report a case of an EP mimicking an endodontic–periodontic lesion.

Methods:

Cone beam CT (CBCT) was performed in a patient to evaluate a radio-opaque nodule observed on the left maxillary first molar during the radiographic examination. Additionally, 23 EPs were evaluated regarding frequency, position, number and morphology by means of µCT. The results were statistically compared using the Student’s t-test for independent samples.

Results:

1 pearl was presented in 13 specimens, while 5 specimens presented 2 pearls. The most frequent location of the EPs was the furcation between the disto-buccal and the palatal roots of the maxillary molars. Overall, the mean major diameter, volume and surface area were 1.98 ± 0.85 mm, 1.76 ± 1.36 mm³ and 11.40 ± 7.59 mm², respectively, with no statistical difference between maxillary second and third molars (p > 0.05). In the case report, CBCT revealed an EP between the disto-buccal and the palatal roots of the maxillary first left molar associated with advanced localized periodontitis. The tooth was referred for extraction.

Conclusions:

EPs, located generally in the furcation area, were observed in 0.74% of the sample. The majority was an enamel–dentin pearl type and no difference was found in maxillary second and third molars regarding diameter, volume and surface area of the pearls. In this report, the EP mimicked an endodontic–periodontic lesion and was a secondary aetiological factor in the periodontal breakdown.     

Perfusion-based assessment of disease activity in untreated and treated patients with aortitis and chronic periaortitis: correlation with CT morphological,clinical and serological data

Objective:

To evaluate the role of perfusion-based assessment of inflammatory activity in patients with treated and untreated aortitis and chronic periaortitis as compared with clinical and serological markers.

Methods:

35 patients (20 females; median age 66 years) with (peri) aortitis were retrospectively evaluated. All patients had clinical symptoms prompting at the time of imaging. All patients first underwent whole-body contrast-enhanced CT and subsequently segmental volume perfusion CT for assessment of the degree of vascularization of (peri) aortitis as a surrogate marker for inflammatory activity. Blood flow, blood volume, volume transfer constant (k-trans), time to peak and mean transit time were determined. The thickness of the increased connective tissue formation was measured. Perfusion data were correlated with clinical symptoms and acute-phase inflammatory parameters such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and leukocyte number.

Results:

21 of 35 patients were untreated and 14 of 35 had previous/ongoing immunosuppression. The interobserver agreement was good (κ = 0.78) for all perfusion parameters. Average values of perfusion parameters were higher in untreated patients but remained abnormally elevated in treated patients as well. Perfusion data and ESR and CRP correlated well both in aortitis (p < 0.05) and in periaortitis (p < 0.05). In periaortitis, perfusion parameters agreed well with ESR and CRP values (p < 0.05) only in untreated patients.

Conclusion:

Perfusion CT parameters in untreated aortitis and chronic periaortitis correlate well with serological markers with respect to disease activity assessment. However, in treated periaortitis, correlations were weak, suggesting an increased role for (perfusion-based) imaging.

Advances in knowledge:

Volume perfusion CT may be used for diagnosis of aortitis/periaortitis.     

Computed tomographic pulmonary changes in patients with chronic rhinosinusitis

Objective:

To investigate whether patients with a diagnosis of chronic rhinosinusitis (CRS) show characteristic pulmonary changes on chest CT compared with a control group without sinusopathy.

Methods:

This retrospective, observational study included patients with and without a diagnosis of CRS who underwent CT examination of the lungs between 2012 and 2014. Two radiologists, who were blinded for the presence of CRS, reviewed the scans for the presence of any abnormalities consensually. The χ² test was used for correlative analysis, with a significance level of 0.05.

Results:

A total of 123 CT series (51.2% from male patients, mean age 41 ± 16 years) were reviewed, including those from 59 (48%) patients with a diagnosis of CRS. Patients with CRS were more likely than the control group to exhibit atelectasis, bronchiolectasis, centrilobular nodules and ground-glass opacities (all p < 0.05), with a significant predilection for middle lobe and lingular involvement observed (p < 0.001). Other abnormalities, such as bronchial wall thickening and air trapping, did not differ between groups.

Conclusion:

Atelectatic changes, ground-glass opacities, bronchiolectasis and centrilobular nodules are the most frequent abnormalities associated with CRS, with peculiar middle lobe and lingular involvement observed on chest CT examinations.

Advances in knowledge:

CRS is a frequent disorder that displays typical pulmonary changes at CT. The recognition of such findings can prevent patients with this condition from undergoing unnecessary investigations that might be based on the presence of the aforementioned radiological features.     

Gemstone spectral imaging reduced artefacts from metal coils or clips after treatment of cerebral aneurysms: a retrospective study of 35 patients

Objective:

This study aimed to evaluate the effect of gemstone spectral imaging (GSI) for metal artefact reduction in cerebral artery CT angiography (CTA) after metal coils or clips treatment.

Methods:

35 patients with cerebral aneurysms were treated with metal coils or clips and underwent CTA using gemstone spectral CT between February and December 2013. The data were reconstructed into three image groups including Group A (quality check images with 140 kVp), Group B (monochromatic image sets in the range of 40–140 keV) and Group C [monochromatic image sets with metal artefacts reduction software (MARS GE Medical Systems, Waukesha, WI)]. CT attenuation value of cerebral artery, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and the subjective score of all images were measured and compared statistically.

Results:

CT attenuation value of cerebral artery decreased in Groups B and C as the photon energy increased. The average energy levels of 60.05 ± 5.37 and 59.93 ± 5.57 keV presented the best CNR in Groups B and C, respectively. CNR values, SNR values and the subjective scores of the image quality of the two sets were higher than those of Group A.

Conclusion:

GSI reduced metal artefact and improved the image quality of CTA after metal coils or clips treatment in patients with cerebral aneurysm. The monochromatic images at the average energy level of 60.05 ± 5.37 keV with MARS and 59.93 ± 5.57 keV without MARS were suggested to be the optimal parameters.

Advances in knowledge:

GSI could reduce metal artefact after metal coils or clips treatment in patients with cerebral aneurysm.     

Radiation exposure of the interventional radiologist during percutaneous biopsy using a multiaxis interventional C-arm CT system with 3D laser guidance: a phantom study

Objective:

Evaluation of absolute radiation exposure values for interventional radiologists (IRs) using a multiaxis interventional flat-panel C-arm cone beam CT (CBCT) system with three-dimensional laser guidance for biopsy in a triple-modality, abdominal phantom.

Methods:

In the phantom, eight lesions were punctured in two different angles (in- and out-of-plane) using CBCT. One C-arm CT scan was performed to plan the intervention and one for post-procedural evaluation. Thermoluminescent dosemeters (TLDs) were used for dose measurement at the level of the eye lens, umbilicus and ankles on a pole representing the IRs. All measurements were performed without any lead protection. In addition, the dose–area product (DAP) and air kerma at the skin entrance point was documented.

Results:

Mean radiation values of all TLDs were 190 µSv for CBCT (eye lens: 180 µS, umbilicus: 230 µSv, ankle: 150 µSv) without a significant difference (p > 0.005) between in- and out-of-plane biopsies. In terms of radiation exposure of the phantom, the mean DAP was not statistically significantly different (p > 0.05) for in- and out-of-plane biopsies. Fluoroscopy showed a mean DAP of 7 or 6 μGym², respectively. C-arm CT showed a mean DAP of 5150 or 5130 μGym², respectively.

Conclusion:

In our setting, the radiation dose to the IR was distinctly high using CBCT. For dose reduction, it is advisable to pay attention to lead shielding, to increase the distance to the X-ray source and to leave the intervention suite for C-arm CT scans.

Advances in knowledge:

The results indicate that using modern navigation tools and CBCT can be accompanied with a relative high radiation dose for the IRs since detector angulation can make the use of proper lead shielding difficult.     

Evaluation of the orbit using contrast-enhanced radial 3D fat-suppressed T1 weighted gradient echo (Radial-VIBE) sequence

Objective:

Contrast-enhanced fat-suppressed T₁ weighted (T1W) two-dimensional (2D) turbo spin echo (TSE) and magnetization-prepared gradient echo (MPRAGE) sequences with water excitation are routinely obtained to evaluate orbit pathology. However, these sequences can be marred by artefacts. The radial-volume-interpolated breath-hold examination (VIBE) sequence is a motion-robust fat-suppressed T1W sequence which has demonstrated value in paediatric and body imaging. The purpose of our study was to evaluate its role in assessing the orbit and to compare it with routinely acquired sequences.

Methods:

A Health Insurance Portability and Accountability Act-compliant and institutional review board-approved retrospective study was performed in 46 patients (age range: 1–81 years) who underwent orbit studies on a 1.5-T MRI system using contrast-enhanced Radial-VIBE, MPRAGE and 2D TSE sequences. Two radiologists blinded to the sequence analysed evaluated multiple parameters of image quality including motion artefact, degree of fat suppression, clarity of choroidal enhancement, intraorbital vessels, extraocular muscles, optic nerves, brain parenchyma and evaluation of pathology. Each parameter was assessed on a 5-point scale, with a higher score indicating the more optimal examination. Mix model analysis of variance and interobserver variability were assessed.

Results:

Radial-VIBE demonstrated superior quality (p < 0.001) for all orbit parameters when compared with MPRAGE and 2D TSE. Interobserver agreement demonstrated average fair-to-good agreement for degree of motion artefact (0.745), fat suppression (0.678), clarity of choroidal enhancement (0.688), vessels (0.655), extraocular muscles (0.675), optic nerves (0.518), brain parenchyma (0.710) and evaluation of pathology (0.590).

Conclusion:

Radial-VIBE sequence demonstrates superior image quality when evaluating the orbits as compared with conventional MPRAGE and 2D TSE sequences.

Advances in knowledge:

Radial-VIBE employs unique non-Cartesian k-space sampling in a radial or spoke-wheel fashion which provides superior image quality improving diagnostic capability in the evaluation of the orbits.     

A quantitative analysis of 1H-MR spectroscopy at 3.0?T of three brain regions from childhood to middle age

Objective:

To study age-related metabolic changes in different brain regions.

Methods:

Point-resolved spectroscopy (repetition time/echo time = 2000 ms/30 ms) was performed in the left and right hippocampus, the left thalamus and the left centrum semiovale of 80 healthy subjects (37 females and 43 males aged 7–64 years). Analysis of covariance and linear regression were used for statistical analysis. Both metabolite concentration ratios with respect to total creatine (tCr) and absolute metabolite concentrations were included for analysis.

Results:

Ins (myo-inositol)/tCr (p < 0.001) and absolute Ins concentration (p = 0.031) were significantly increased with age after adolescence. NAA (N-acetylaspartic acid)/tCr (p < 0.001) and absolute NAA concentration (p = 0.010) significantly declined with age after adolescence.

Conclusion:

Age-related increase of Ins and decline of NAA are found in all three regions, especially at the hippocampus, indicating possible gliosis in the ageing brain.

Advances in knowledge:

We could use NAA/tCr and Ins/tCr as an indicator to estimate the neurons-to-glial cells ratio at the thalamus. This may be an index to distinguish normal tissues from gliosis.     

Evaluation of Adrenal Masses in Lung Cancer Patients Using F-18 FDG PET/CT

Purpose

The aim of this study was to assess the diagnostic efficacy of PET/CT using various parameters for the characterization of adrenal nodules in lung cancer patients.

Methods

Sixty-one adrenal nodules in 51 lung cancer patients were evaluated. The final diagnosis was based on histology (n = 2) or imaging follow-up (n = 59, range of follow-up: 7–57 months, median 27 months). Each adrenal nodule was analyzed using four parameters of PET/CT: the maximum standardized uptake value (SUV_max), the adrenal nodule/liver ratio of the SUV (SUV ratio), Hounsfield units (HU) and size. The optimal cutoff of each parameter for the identification of metastatic nodule was determined by ROC analysis and then the diagnostic efficacy was compared among the parameters.

Results

Of the 61 adrenal nodules, 45 (73%) were considered metastasis. The optimal cutoff values of the parameters were SUV_max >2.7, SUV ratio >1.3, HU >18 and size >20 mm, respectively. The sensitivity, specificity and accuracy by SUV_max >2.7 were 88.9%, 87.5% and 88.5%, and those by SUV ratio >1.3 were 84.4%, 100% and 88.5%, respectively. The combination of SUV ratio >1.3 and HU >18 had sensitivity of 97.7%, specificity of 81.2% and accuracy of 93.4% to predict adrenal metastasis in patients with lung cancer.

Conclusion

SUV ratio from F-18 FDG PET/CT could identify the adrenal metastasis in lung cancer patients. The combination of SUV ratio and HU can improve the accuracy of differentiating benign and metastatic adrenal lesions in lung cancer patients.     

MR relaxometry for the facial ageing assessment: the preliminary study of the age dependency in the MR relaxometry parameters within the facial soft tissue

Objectives:

To investigate the location-specific tissue properties and age-related changes of the facial fat and facial muscles using quantitative MRI (qMRI) analysis of longitudinal magnetization (T1) and transverse magnetization (T2) values.

Methods:

38 subjects (20 males and 18 females, 0.5–87 years old) were imaged with a mixed turbo-spin echo sequence at 1.5 T. T1 and T2 measurements were obtained within regions of interest in six facial fat regions including the buccal fat and subcutaneous cheek fat, four eyelid fat regions (lateral upper, medial upper, lateral lower and medial lower) and five facial muscles including the orbicularis oculi, orbicularis oris, buccinator, zygomaticus major and masseter muscles bilaterally.

Results:

Within the zygomaticus major muscle, age-associated T1 decreases in females and T1 increases in males were observed in later life with an increase in T2 values with age. The orbicularis oculi muscles showed lower T1 and higher T2 values compared to the masseter, orbicularis oris and buccinator muscles, which demonstrated small age-related changes. The dramatic age-related changes were also observed in the eyelid fat regions, particularly within the lower eyelid fat; negative correlations with age in T1 values (p < 0.0001 for age) and prominent positive correlation in T2 values in male subjects (p < 0.0001 for male × age). Age-related changes were not observed in T2 values within the subcutaneous cheek fat.

Conclusions:

This study demonstrates proof of concept using T1 and T2 values to assess age-related changes of the facial soft tissues, demonstrating tissue-specific qMRI measurements and non-uniform ageing patterns within different regions of facial soft tissues.     

Imaging Atherosclerosis in the Carotid Arteries with F-18-Fluoro-2-deoxy-D-glucose Positron Emission Tomography: Effect of Imaging Time after Injection on Quantitative Measurement

Purpose

To compare F-18-fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) imaging at two different circulation times after injection of F-18 FDG in order to measure atherosclerosis in carotid arteries.

Methods

We assessed 12 patients with recent symptomatic plaques in the carotid arteries. F-18 FDG PET/CT carotid plaque imaging was performed for 20 min at 2 h after F-18 FDG injection in five patients and at 3 h in seven patients. We measured vessel wall uptake using the maximal standardized uptake value (SUV), and the mean and maximal blood target-to-background ratios (TBR) of the symptomatic carotid arteries. Blood pool activity (BPA) was measured as the mean SUV of the superior vena cava (SVC) and jugular vein of these 12 patients, and in 14 age- and gender-matched patients who underwent whole-body F-18 FDG PET/CT examinations 1 h after injection.

Results

F-18 FDG PET/CT revealed visible F-18 FDG uptake in all patients with symptomatic carotid plaques. Maximal SUV did not differ between groups evaluated at 2 h and 3 h (2.62 ± 0.45 vs 3.00 ± 0.85, p = 0.335). However, mean (2.04 ± 0.22 vs 3.54 ± 0.62, p < 0.05) and maximal (1.65 ± 0.15 vs 2.70 ± 0.42, p < 0.05) TBR values that were normalized to BPA in the SVC differ significantly.

Conclusions

Symptomatic carotid plaques are visualized for a relatively short period of imaging time on ≥1-h PET/CT images. Quantitative parameters of atherosclerotic carotid arteries are preserved or even increased over time, whereas those of blood pools are decreased.     

Retrocrural Lymph Node Metastasis Disclosed by 18F-FDG PET/CT: A Predictor of Supra-diaphragmatic Spread in Ovarian Cancer

Purpose

Retrocrural lymph nodes (RCLNs) communicate with retroperitoneal and posterior mediastinal LNs. It is possible that, when RCLNs are involved, supra-diaphragmatic extension will occur in abdomino-pelvic cancers. The authors investigated performance of ¹⁸F-FDG PET/CT to diagnose RCLN metastasis and whether RCLN metastases were associated with supra-diaphragmatic lymphatic metastases of ovarian cancer.

Materials and methods

Sixty-seven patients with stage IV ovarian cancer who had undergone ¹⁸F-FDG PET/CT were included in this retrospective study. Diagnostic performance of ¹⁸F-FDG PET/CT for RCLN metastasis was evaluated. Patients were divided into two groups by presence or absence of supra-diaphragmatic LN metastasis. The prevalences of RCLN metastasis between the two groups were compared and the odds ratio was calculated.

Results

Sensitivity and specificity of ¹⁸F-FDG PET/CT for RCLN metastasis were 96.3 and 100%, respectively. Of the 67 study subjects, 27 patients had RCLN metastases (40.3%). Fifty patients had supra-diaphragmatic LN metastases. ¹⁸F-FDG PET/CT showed 26 RCLN metastases in patients with supra-diaphragmatic LN metastases (54.5%), and only 1 in patients without supra-diaphragmatic LN metastasis (5.9%), and the difference between two groups was statistically significant (P < 0.05). The odds ratio that patients with RCLN metastasis would have supra-diaphragmatic LN metastasis was 17.3 (95% confidence interval = 2.1 to 140.9, P = 0.008).

Conclusion

Performance of ¹⁸F-FDG PET/CT to diagnose RCLN metastasis was excellent. RCLN metastasis revealed by ¹⁸F-FDG PET/CT was strongly associated with supra-diaphragmatic LN spread of ovarian cancer. Thus, RCLN metastasis could be used as a predictor of supra-diaphragmatic lymphatic metastasis of ovarian cancer.