Variability of average SUV from several hottest voxels is lower than that of SUVmax and SUVpeak

Objectives

To assess variability of the average standard uptake value (SUV) computed by varying the number of hottest voxels within an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)-positive lesion. This SUV metric was compared with the maximal SUV (SUV_max: the hottest voxel) and peak SUV (SUV_peak: SUV_max and its 26 neighbouring voxels).

Methods

Twelve lung cancer patients (20 lesions) were analysed using PET dynamic acquisition involving ten successive 2.5-min frames. In each frame and lesion, average SUV obtained from the N?=?5, 10, 15, 20, 25 or 30 hottest voxels (SUV_max–N )_, SUV_max and SUV_peak were assessed. The relative standard deviations (SDrs) from ten frames were calculated for each SUV metric and lesion, yielding the mean relative SD from 20 lesions for each SUV metric (SDr _N , SDr_max and SDr_peak), and hence relative measurement error and repeatability (MEr–R).

Results

For each N, SDr _N was significantly lower than SDr_max and SDr_peak. SDr _N correlated strongly with N: 6.471?×?N ^-0.103 (r?=?0.994; P?<?0.01). MEr–R of SUV_max-30 was 8.94–12.63 % (95 % CL), versus 13.86–19.59 % and 13.41–18.95 % for SUV_max and SUV_peak respectively.

Conclusions

Variability of SUV_max–N is significantly lower than for SUV_max and SUV_peak. Further prospective studies should be performed to determine the optimal total hottest volume, as voxel volume may depend on the PET system.

Key Points

? PET imaging provides functional parameters of ¹⁸ F-FDG-positive lesions, such as SUVmax and SUVpeak. ? Averaging SUV from several hottest voxels (SUVmax- _N ) is a further SUV metric. ? Variability of SUVmax– _N is significantly lower than SUVmax and SUVpeak variability. ? SUVmax– _N should improve SUV accuracy for predicting outcome or assessing treatment response. ? An optimal total hottest volume should be determined through further prospective studies.     

Metabolic tumour volumes measured at staging in lymphoma: methodological evaluation on phantom experiments and patients

Purpose

The presence of a bulky tumour at staging on CT is an independent prognostic factor in malignant lymphomas. However, its prognostic value is limited in diffuse disease. Total metabolic tumour volume (TMTV) determined on ¹⁸F-FDG PET/CT could give a better evaluation of the total tumour burden and may help patient stratification. Different methods of TMTV measurement established in phantoms simulating lymphoma tumours were investigated and validated in 40 patients with Hodgkin lymphoma and diffuse large B-cell lymphoma.

Methods

Data were processed by two nuclear medicine physicians in Reggio Emilia and Créteil. Nineteen phantoms filled with ¹⁸F-saline were scanned; these comprised spherical or irregular volumes from 0.5 to 650 cm³ with tumour-to-background ratios from 1.65 to 40. Volumes were measured with different SUVmax thresholds. In patients, TMTV was measured on PET at staging by two methods: volumes of individual lesions were measured using a fixed 41 % SUVmax threshold (TMTV₄₁) and a variable visually adjusted SUVmax threshold (TMTV_var).

Results

In phantoms, the 41 % threshold gave the best concordance between measured and actual volumes. Interobserver agreement was almost perfect. In patients, the agreement between the reviewers for TMTV₄₁ measurement was substantial (ρ _c?=?0.986, CI 0.97 – 0.99) and the difference between the means was not significant (212?±?218 cm³ for Créteil vs. 206?±?219 cm³ for Reggio Emilia, P?=?0.65). By contrast the agreement was poor for TMTV_var. There was a significant direct correlation between TMTV₄₁ and normalized LDH (r?=?0.652, CI 0.42 – 0.8, P <0.001). Higher disease stages and bulky tumour were associated with higher TMTV₄₁, but high TMTV₄₁ could be found in patients with stage 1/2 or nonbulky tumour.

Conclusion

Measurement of baseline TMTV in lymphoma using a fixed 41% SUVmax threshold is reproducible and correlates with the other parameters for tumour mass evaluation. It should be evaluated in prospective studies.     

Diagnostic performance of 18F-fluorothymidine PET/CT for primary colorectal cancer and its lymph node metastasis: comparison with 18F-fluorodeoxyglucose PET/CT

Purpose

To examine the diagnostic performance of ¹⁸F-fluorothymidine (FLT) PET/CT in primary and metastatic lymph node colorectal cancer foci in comparison with ¹⁸F-fluorodeoxyglucose (FDG) PET/CT.

Methods

The study population comprised 28 patients with 30 newly diagnosed colorectal cancers who underwent surgical resection of the primary lesion and regional lymph nodes after both FLT and FDG PET/CT. The associations between SUVmax levels and pathological factors were evaluated using the Mann-Whitney U or Kruskal-Wallis test. Differences in diagnostic indexes for detecting nodal metastasis between the two tracers were estimated using the McNemar exact or χ ² test.

Results

All 30 primary cancers (43.0?±?20.0 mm, range 14 – 85 mm) were visualized by both tracers, but none of the FLT SUVmax values exceeded the FDG SUVmax values in any of the primary cancers (6.6?±?2.4 vs. 13.6?±?5.8, p?<?0.001). The sensitivity, specificity and accuracy for detecting nodal metastasis were 41 % (15/37), 98.8 % (493/499) and 94.8 % (508/536) for FDG PET/CT, and 32 % (12/37), 98.8 % (493/499) and 94.2 % (505/536) for FLT PET/CT, respectively. The sensitivity (p?=?0.45), specificity (p?=?0.68) and accuracy (p?=?0.58) were not different between the tracers. Nodal uptake of FLT and FDG was discordant in 7 (19 %) of 37 metastatic nodes. There were ten concordant true-positive nodes of which six showed higher FDG SUVmax and four showed higher FLT SUVmax, but the difference between FDG and FLT SUVmax was not significant (5.56?±?3.55 and 3.62?±?1.45, respectively; p?=?0.22).

Conclusion

FLT has the same potential as FDG in PET/CT for the diagnosis of primary and nodal foci of colorectal cancer despite significantly lower FLT uptake in primary foci.     

The increment in standardized uptake value determined using dual-phase 18F-FDG PET is a promising prognostic factor in non-small-cell lung cancer

Purpose

We aimed to determine whether the increment in the maximal standardized uptake value (SUVmax) of the primary lung tumour between the initial and delayed imaging by dual-phase ¹⁸F-FDG PET has prognostic value in patients with non-small-cell lung cancer (NSCLC).

Methods

We reviewed the records of patients with NSCLC who underwent pretreatment dual-phase ¹⁸F-FDG PET/CT scans acquired at 1 h and 2 h after injection. The SUVmax increment (SUVinc) of the primary lung tumour was the 2-h SUVmax minus the 1-h SUVmax. Univariate and multivariate analyses were used to assess the prognostic significance of SUVinc, retention index, whole-body total metabolic tumour volume, whole-body total lesion glycolysis (TLGwb), 1-h SUVmax, 2-h SUVmax, gender, age, performance status, histological subtype, T stage, N stage and clinical stage.

Results

The records of 187 consecutive patients were reviewed. The median follow-up time was 3.9 years. The estimated median progression-free survival (PFS) and overall survival (OS) were 1.3 years and 4.4 years, respectively. An SUVinc cut-off value of >1 had the best discriminative yield for PFS. The 3-year PFS and OS were 61.6 % and 87.8 % in patients with SUVinc ≤1 versus 21.1 % and 46.2 % in patients with SUVinc >1 (all P?<?0.01). Using the forward stepwise multivariate Cox proportional hazards model, SUVinc, TLGwb, and clinical stage were significant factors for PFS (all P?<?0.01). A subgroup analysis of 117 patients treated with surgery showed that SUVinc (P?=?0.02) and clinical stage (P?<?0.01) were significant prognostic factors for PFS. Furthermore, in stage I patients treated with surgery alone, SUVinc was the only significant prognostic factor (HR 28.07; 95 % CI 2.42 – 326.41).

Conclusion

SUVinc determined from dual-phase ¹⁸F-FDG PET is a promising prognostic factor for NSCLC. It adds to the value of dual-phase ¹⁸F-FDG PET.     

Prognostic value of volumetric parameters measured by 18F-FDG PET/CT in patients with head and neck squamous cell carcinoma

Purpose

The objective of this study was to investigate the value of metabolic tumour volume (MTV) assessed with ¹⁸F-FDG PET/CT in predicting event-free survival (EFS) and overall survival (OS) in patients with head and neck squamous cell carcinoma (HNSCC), and particularly to compare it with more conventional parameters such as maximum standardized uptake value (SUVmax).

Methods

Patients referred to our department for ¹⁸F-FDG PET/CT for staging of HNSCC were prospectively included between February 2009 and March 2011. Each patient was scanned using a Philips Gemini PET/CT system at 1 h after injection. The MTV was calculated semiautomatically for the primary site using methods based on SUV with various thresholds: 3-D contour around voxels equal to or greater than 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 times SUV, or more than 30 %, 40 % and 50 % of SUVmax. ROC analysis was used to test the statistical significance of the differences among the calculated MTVs. EFS and OS were determined using the Kaplan-Meier method and compared with MTV in univariate and multivariate analyses, including the usual prognostic factors: age, sex, primary site, treatment, SCC histologic grade, AJCC stage, TNM classification, tumour SUVmax and SUVpeak.

Results

The study included 80 consecutive patients (70 men, 10 women; mean age 62.4?±?9.0 years). ROC analysis revealed that pretreatment MTV using a threshold of 5.0 times SUV (MTV5.0) was the best parameter to predict recurrence and death after treatment. In univariate analysis, MTV5.0 >4.9 ml was predictive of poor EFS (p?<?0.0001) and poor OS (p?<?0.0001). In multivariate, MTV5.0 persisted as an independent predictive factor for EFS (p?=?0.011) and OS (p?=?0.010), while SUVmax became nonsignificant (p?=?0.277 for EFS, p?=?0.975 for OS).

Conclusion

Our results suggest that MTV measured by ¹⁸F-FDG PET/CT has independent prognostic value of in patients with HNSCC, stronger than SUVmax.     

What parameters from 18F-FDG PET/CT are useful in evaluation of adrenal lesions?

Purpose

Prior studies have suggested that ¹⁸F-FDG PET/CT can help characterize adrenal lesions and differentiate adrenal metastases from benign lesions. The aim of this study was to assess the value of ¹⁸F-FDG PET/CT for the differentiation of malignant from benign adrenal lesions.

Methods

This retrospective study included 85 patients (47 men and 38 women, age 63.8?±?10.8 years) who had undergone ¹⁸F-FDG PET/CT (60 min after injection 300 – 370 MBq ¹⁸F-FDG; Biograph 64 scanner) for evaluation of 102 nonsecreting adrenal masses. For semiquantitative analysis, the maximum standardized uptake value (SUVmax), adrenal to liver (T/L) SUVmax ratio, mean CT attenuation value and tumour diameter were measured in all lesions and compared with the pathological findings.

Results

Malignant adrenal tumours (68 % of evaluated tumours) had a significantly higher mean SUVmax (13.0?±?7.1 vs. 3.7?±?3.0), a higher T/L SUVmax ratio (4.2?±?2.6 vs. 1.0?±?0.9), a higher CT attenuation value (31.9?±?16. 7 HU vs. 0.2?±?25.8 HU) and a greater diameter (43.6?±?23.7 mm vs. 25.6?±?13.3 mm) than benign lesions. The false-positive findings were tuberculosis and benign phaeochromocytoma. Based on ROC analysis, a T/L SUVmax ratio >1.53, an adrenal SUVmax >5.2, an attenuation value >24 HU and a tumour diameter >30 mm were chosen as the optimal cut-off values for differentiating malignant from benign tumours. The areas under the ROC curves for the selected cut-off values were 0.96, 0.96, 0.88 and 0.77, respectively. A multivariate logistic regression model revealed that the T/L SUVmax ratio was an independent prognostic factor for malignancy (p?25 HU and a tumour diameter >30 mm had no additional individual importance in the diagnosis of malignancy.

Conclusion

Using a T/L SUVmax ratio >1.53 and an adrenal SUVmax >5.2 in ¹⁸F-FDG PET/CT led to high diagnostic sensitivity, specificity and negative predictive value for characterizing adrenal tumours. The diagnostic accuracies of the two parameters were comparable, but T/L SUVmax ratio was an independent predictor of malignancy.     

Differentiating primary CNS lymphoma from glioblastoma multiforme: assessment using arterial spin labeling, diffusion-weighted imaging, and 18F-fluorodeoxyglucose positron emission tomography

Introduction

Our purpose was to evaluate the diagnostic performance of arterial spin labeling (ASL) perfusion imaging, diffusion-weighted imaging (DWI), and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating primary central nervous system lymphomas (PCNSLs) from glioblastoma multiformes (GBMs).

Methods

Fifty-six patients including 19 with PCNSL and 37 with GBM were retrospectively studied. From the ASL data, an absolute tumor blood flow (aTBF) and a relative tumor blood flow (rTBF) were obtained within the enhancing portion of each tumor. In addition, the minimum apparent diffusion coefficient (ADCmin) and the maximum standard uptake value (SUVmax) were obtained from DWI and FDG-PET data, respectively. Each of the four parameters was compared between PCNSLs and GBMs using Kruskal–Wallis test. The performance in discriminating between PCNSLs and GBMs was evaluated using the receiver-operating characteristics analysis. Area-under-the-curve (AUC) values were compared among the four parameters using a nonparametric method.

Results

The aTBF, rTBF, and ADCmin were significantly higher in GBMs (mean aTBF ± SD?=?91.6?±?56.0 mL/100 g/min, mean rTBF ± SD?=?2.61?±?1.61, mean ADCmin ± SD?=?0.78?±?0.19?×?10^?3 mm²/s) than in PCNSLs (mean aTBF ± SD?=?37.3?±?10.5 mL/100 g/min, mean rTBF ± SD?=?1.24?±?0.37, mean ADCmin ± SD?=?0.61?±?0.13?×?10^?3 mm²/s) (p?<?0.005, respectively). In addition, SUVmax was significantly lower in GBMs (mean ± SD?=?13.1?±?6.34) than in PCNSLs (mean ± SD?=?22.5?±?7.83) (p?<?0.005). The AUC for aTBF (0.888) was higher than those for rTBF (0.810), ADCmin (0.768), and SUVmax (0.848), although their difference was not statistically significant.

Conclusion

ASL perfusion imaging is useful for differentiating PCNSLs from GBMs as well as DWI and FDG-PET.     

Contrast agent bolus tracking with a fixed threshold or a manual fast start for coronary CT angiography

Objectives

Comparison of bolus tracking with a fixed threshold versus a manual fast start for coronary CT angiography.

Methods

We retrospectively analysed 320-row coronary CT angiography of 50 patients with suspected or known coronary artery disease. Twenty-five examinations were initiated by a bolus tracking method (group 1), 25 examinations with a manual fast surestart (group 2).

Results

Mean attenuation values in the ascending aorta were 519?±?111 Hounsfield units (HU) in group 1 and 476?±?65 HU in group 2 (p?=?0.10). Assessable vessel lengths were 171?±?44 mm vs 172?±?29 mm for the right coronary artery (p?=?0.91), 11?±?4 mm vs 12?±?4 mm for the left main (p?=?0.9), 163?±?28 mm vs 151?±?26 mm for the left anterior descending coronary artery (p?=?0.11) and 125?±?41 mm vs 110?±?37 mm for the left circumflex coronary artery (p?=?0.18). Image quality for all coronary arteries was not significantly different between the groups (p?>?0.41). The attenuation ratio between the left and right ventricle was 2.8?±?0.7 vs 3.6?±?1.0 (p?=?0.003). Significantly less contrast agent was used in group 2 (64?±?6 ml vs 80?±?0 ml; p?<?0.001).

Conclusions

Bolus tracking with a fixed threshold and with a manual fast start are both suitable methods; the fast start allowed a reduction of contrast agent volumes.

Key Points

? Fixed threshold bolus tracking is suitable for coronary 320-row CT angiography ? Manual fast start bolus tracking can reduce contrast agent volumes ? Manual fast start and fixed threshold initiation achieve good image quality ? Fixed threshold bolus tracking achieves a more reliable contrast bolus position     

Fifteen different 18F-FDG PET/CT qualitative and quantitative parameters investigated as pathological response predictors of locally advanced rectal cancer treated by neoadjuvant chemoradiation therapy

Purpose

The aim of this study was to correlate qualitative visual response and various PET quantification factors with the tumour regression grade (TRG) classification of pathological response to neoadjuvant chemoradiotherapy (CRT) proposed by Mandard.

Methods

Included in this retrospective study were 69 consecutive patients with locally advanced rectal cancer (LARC). FDG PET/CT scans were performed at staging and after CRT (mean 6.7 weeks). Tumour SUVmax and its related arithmetic and percentage decrease (response index, RI) were calculated. Qualitative analysis was performed by visual response assessment (VRA), PERCIST 1.0 and response cut-off classification based on a new definition of residual disease. Metabolic tumour volume (MTV) was calculated using a 40 % SUVmax threshold, and the total lesion glycolysis (TLG) both before and after CRT and their arithmetic and percentage change were also calculated. We split the patients into responders (TRG 1 or 2) and nonresponders (TRG 3–5).

Results

SUVmax MTV and TLG after CRT, RI, ΔMTV% and ΔTLG% parameters were significantly correlated with pathological treatment response (p?<?0.01) with a ROC curve cut-off values of 5.1, 2.1 cm³, 23.4 cm³, 61.8 %, 81.4 % and 94.2 %, respectively. SUVmax after CRT had the highest ROC AUC (0.846), with a sensitivity of 86 % and a specificity of 80 %. VRA and response cut-off classification were also significantly predictive of TRG response (VRA with the best accuracy: sensitivity 86 % and specificity 55 %). In contrast, assessment using PERCIST was not significantly correlated with TRG.

Conclusion

FDG PET/CT can accurately stratify patients with LARC preoperatively, independently of the method chosen to interpret the images. Among many PET parameters, some of which are not immediately obtainable, the most commonly used in clinical practice (SUVmax after CRT and VRA) showed the best accuracy in predicting TRG.     

Diagnostic accuracy of 18F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma

Purpose

To evaluate the diagnostic accuracy of ¹⁸F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma.

Methods

We retrospectively analysed data from 53 patients (age 20.1?±?10.5 years, 39 male) who had undergone 71 ¹⁸F-FDG PET/CT studies for suspected recurrence (52 studies) or for routine follow-up (19 studies) after primary therapy of skeletal Ewing sarcoma. ¹⁸F-FDG PET/CT studies were evaluated qualitatively and quantitatively (maximum standardized uptake value, SUVmax) by two nuclear medicine physicians in consensus. Sensitivity, specificity, predictive values and accuracy were calculated on per study basis. Clinical/imaging follow-up (minimum 6 months) and/or histopathology (when available) were taken as the reference standard.

Results

Of the total of 71 ¹⁸F-FDG PET/CT studies, 42 (59.1 %) were positive for recurrence and 29 (40.9 %) were negative for recurrence. Local recurrence was most common (38 studies) followed by bone metastasis (9 studies), and node and lung metastasis (2 studies each). Of the 71 studies, 38 were true-positive, 27 were true-negative, 4 were false-positive and 2 were false-negative. Overall per study based sensitivity was 95 %, specificity was 87 %, PPV was 90 %, NPV was 93 % and accuracy was 91.5 %. No significant difference was found in the accuracy of PET/CT between the suspected recurrence group and the routine follow-up group (94 % vs. 84 %; P?=?0.390). Overall mean lesion SUVmax was 7.8?±?4.1 (range 1.9–17.2). No site-based difference was found in SUVmax.

Conclusion

¹⁸F-FDG PET/CT demonstrates high diagnostic accuracy for detecting recurrence in patients with primary skeletal Ewing sarcoma, when it is suspected (clinically or on imaging) or during routine follow-up.     

O-(2-[18F]fluoroethyl)-l-tyrosine uptake is an independent prognostic determinant in patients with glioma referred for radiation therapy

Aim

To evaluate the prognostic value of O-(2-[¹⁸F]fluoroethyl)-l-tyrosine positron emission tomography (FET-PET) uptake intensity in World Health Organisation (WHO) tumor grade II–IV gliomas.

Methods

We studied 28 patients with WHO tumor grade II–IV gliomas who were referred to our department for radiation therapy. We acquired a FET-PET in all patients, as well as magnetic resonance imaging (MRI) of the brain consisting of at least T2-weighted imaging, flair and pre- and post-contrast T1-weighted imaging. SUVmax was measured and the tumor-to-brain uptake ratio (TBR) of all lesions was calculated based on the SUVmax (TBRmax) or SUVmean (TBRmean) of the contralateral healthy tissue. For this study, volumes were calculated using MRI alone, MRI + the volume with a SUVmax on FET-PET ≥ 2.2 as well as MRI + the volume with an uptake of at least 40 % of the SUVmax.

Results

Tumor volumes were a median (range) of 88.6 (2.6–467.4) ml (MRI alone), 84.2 (2.8–474.4) ml (MRI + SUVmax on FET-PET ≥ 2.2) and 101.5 (4.0–512.1) ml (MRI + FET-PET uptake ≥ 40 % SUVmax), respectively. TBR-SUVmean was 2.36 (1.46–4.08); TBR-SUVmax was 1.71 (0.97–2.85). During a follow-up of 18.7 (2.5–36.1) months after FET-PET, 12 patients died of malignant glioma. Patients with a SUVmax ≥ 2.6 had a significantly worse tumor-related mortality (p = 0.005) and progression-free survival (p = 0.038) than those with a lower SUVmax. Multivariate analysis showed that WHO tumor grade (p = 0.001) and SUVmax ≥ 2.6 (p < 0.001) were independent predictors for tumor-related mortality, but not tumor volume or TBRmax or TBRmean. SUVmax ≥ 2.6 (p = 0.007) and being treated for a recurrence rather than for a primary tumor manifestation (p = 0.014) were predictors for progression-free survival, but not TBRmax or TBRmean.

Conclusion

In this heterogeneous patient population, higher tracer uptake in FET-PET appears to be associated with a worse tumor-related mortality and a shorter duration of the disease-free interval.     

Dynamic contrast-enhanced CT to assess metabolic response in patients with advanced non-small cell lung cancer and stable disease after chemotherapy or chemoradiotherapy

Objectives

To compare tumour enhancement patterns measured using dynamic contrast-enhanced (DCE)-CT with tumour metabolism measured using positron emission tomography (PET)-CT in patients with non-small cell lung cancer (NSCLC) and stable disease after chemotherapy or chemoradiotherapy.

Methods

After treatment, 75 NSCLC tumours in 65 patients who had stable disease on DCE-CT according to Response Evaluation Criteria in Solid Tumour (RECIST) were evaluated using PET-CT. On DCE-CT, relative enhancement ratios (RER) of tumour at 30, 60, 90, 120 s and 5 min after injection of contrast material were measured. Metabolic responses of tumours were classified into two groups according to the maximum standardized uptake value (SUVmax) by PET-CT: complete metabolic response (CR) with an SUVmax of less than 2.5, and noncomplete metabolic response (NR) with an SUVmax of at least 2.5.

Results

Using the optimal RER₆₀ cutoff value of 43.7 % to predict NR of tumour gave 95.7 % sensitivity, 64.2 % specificity, and 82.1 % positive and 95.0 % negative predictive values. After adjusting for tumour size, the odds ratio for NR in tumour with an RER₆₀ of at least 43.7 % was 70.85 (95 % CI?=?7.95–630.91; P?<?0.05).

Conclusions

Even when disease was stable according to RECIST, DCE-CT predicted hypermetabolic status of residual tumour in patients with NSCLC after treatment.

Key Points

? Dynamic contrast-enhanced CT (DCE-CT) can provide useful metabolic information about non-small cell lung cancer. ? NSCLC lesions, even grossly stable after treatment, show various metabolic states. ? DCE-CT enhancement patterns correlate with tumour metabolic status as shown by PET. ? DCE-CT helps to assess hypermetabolic NSCLC as stable disease after treatment.     

Contrast-enhanced ultrasound of focal nodular hyperplasia: a matter of size

Objectives

To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size.

Methods

Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout.

Results

Mean FNH-lesion size was 3.7?±?2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm (P?–4). Size and frequency of centrifugal enhancement were negatively correlated (r?=?–0.57, P?–4). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) (P?–3). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7?±?1.7 and 3.6?±?2.0 cm (P?=?0.012).

Conclusions

Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm.

Key Points

? CEUS yields confident diagnoses of FNHs ≤3.1 cm ? The larger the FNH, the lower the diagnostic sensitivity of CEUS ? Final diagnosis of FNHs >3.1 cm should be obtained with MRI not CEUS     

Cardiac valve calcifications on low-dose unenhanced ungated chest computed tomography: inter-observer and inter-examination reliability,agreement and variability

Objectives

To determine inter-observer and inter-examination variability for aortic valve calcification (AVC) and mitral valve and annulus calcification (MC) in low-dose unenhanced ungated lung cancer screening chest computed tomography (CT).

Methods

We included 578 lung cancer screening trial participants who were examined by CT twice within 3 months to follow indeterminate pulmonary nodules. On these CTs, AVC and MC were measured in cubic millimetres. One hundred CTs were examined by five observers to determine the inter-observer variability. Reliability was assessed by kappa statistics (κ) and intra-class correlation coefficients (ICCs). Variability was expressed as the mean difference ± standard deviation (SD).

Results

Inter-examination reliability was excellent for AVC (κ?=?0.94, ICC?=?0.96) and MC (κ?=?0.95, ICC?=?0.90). Inter-examination variability was 12.7?±?118.2 mm³ for AVC and 31.5?±?219.2 mm³ for MC. Inter-observer reliability ranged from κ?=?0.68 to κ?=?0.92 for AVC and from κ?=?0.20 to κ?=?0.66 for MC. Inter-observer ICC was 0.94 for AVC and ranged from 0.56 to 0.97 for MC. Inter-observer variability ranged from -30.5?±?252.0 mm³ to 84.0?±?240.5 mm³ for AVC and from -95.2?±?210.0 mm³ to 303.7?±?501.6 mm³ for MC.

Conclusions

AVC can be quantified with excellent reliability on ungated unenhanced low-dose chest CT, but manual detection of MC can be subject to substantial inter-observer variability. Lung cancer screening CT may be used for detection and quantification of cardiac valve calcifications.

Key points

? Low-dose unenhanced ungated chest computed tomography can detect cardiac valve calcifications. ? However, calcified cardiac valves are not reported by most radiologists. ? Inter-observer and inter-examination variability of aortic valve calcifications is sufficient for longitudinal studies. ? Volumetric measurement variability of mitral valve and annulus calcifications is substantial.     

Adrenal gland volume measurement in septic shock and control patients: a pilot study

Objectives:

To compare adrenal gland volume in septic shock patients and control patients by using semi-automated volumetry.

Methods:

Adrenal gland volume and its inter-observer variability were measured with tomodensitometry using semi-automated software in 104 septic shock patients and in 40 control patients. The volumes of control and septic shock patients were compared and the relationship between volume and outcome in intensive care was studied.

Results:

The mean total volume of both adrenal glands was 7.2?±?2.0 cm³ in control subjects and 13.3?±?4.7 cm³ for total adrenal gland volume in septic shock patients (p?<?0.0001). Measurement reproducibility was excellent with a concordance correlation coefficient value of 0.87. The increasing adrenal gland volume was associated with a higher rate of survival in intensive care.

Conclusion:

The present study reports that with semi-automated software, adrenal gland volume can be measured easily and reproducibly. Adrenal gland volume was found to be nearly double in sepsis compared with control patients. The absence of increased volume during sepsis would appear to be associated with a higher rate of mortality and may represent a prognosis factor which may help the clinician to guide their strategy.     

Long-term results of preventive embolization of renal angiomyolipomas: evaluation of predictive factors of volume decrease

Objectives

To evaluate the efficacy of selective arterial embolization (SAE) of angiomyolipomas based on the percentage volume reduction after embolization and to identify predictive factors of volume decrease.

Methods

Patients receiving prophylactic SAE of renal angiomyolipomas were included retrospectively over 3 years. The volume change after SAE and haemorrhagic or surgical events were recorded. Initial tumour volume, percentage tumour fat content, mean tumour density, embolic agent used, number of angiomyolipomas and tuberous sclerosis disease were evaluated as predictive factors of volume decrease.

Results

A total of 19 patients with 39 angiomyolipomas were included with median follow-up of 28 months (interquartile range 21–37 months). All treatments were technically successful (92 % primary and 8 % secondary). No distal bleeding or any increase in size or surgical nephrectomy after SAE was recorded. Mean volume reduction was 72 % (±24 %). Volumes before SAE (R ²?=?0.276; p?=?0.001), percentage fat content (R ²?=?0.612; p?<?0.0001) and mean angiomyolipoma density (R ²?=?0.536; p?<?0.0001) were identified as predictive factors of volume decrease. In multivariate regression, only percentage fat content influenced volume decreases.

Conclusions

SAE is an efficient treatment for angiomyolipoma devascularisation and volume reduction. A significant reduction of volume is modulated by the initial volume and tissue composition of the tumour.

Key Points

? Selective arterial embolization is effective for angiomyolipoma devascularisation and volume reduction ? Volume reduction depends of initial volume and tissue composition of the tumour ? Selective arterial embolization is a low radiation treatment     

Anatomical and functional volume concordance between FDG PET,and T2 and diffusion-weighted MRI for cervical cancer: a hybrid PET/MR study

Purpose

To evaluate the concordance among ¹⁸F-FDG PET imaging, MR T2-weighted (T2-W) imaging and apparent diffusion coefficient (ADC) maps with diffusion-weighted (DW) imaging in cervical cancer using hybrid whole-body PET/MR.

Methods

This study prospectively included 35 patients with cervical cancer who underwent pretreatment ¹⁸F-FDG PET/MR imaging. ¹⁸F-FDG PET and MR images were fused using standard software. The percent of the maximum standardized uptake values (SUV_max) was used to contour tumours on PET images, and volumes were calculated automatically. Tumour volumes measured on T2-W and DW images were calculated with standard techniques of tumour area multiplied by the slice profile. Parametric statistics were used for data analysis.

Results

FDG PET tumour volumes calculated using SUV_max (14.30?±?4.70) and T2-W imaging volume (33.81?±?27.32 cm³) were similar (P?>?0.05) at 35 % and 40 % of SUV_max (32.91?±?18.90 cm³ and 27.56?±?17.19 cm³ respectively) and significantly correlated (P?<?0.001; r?=?0.735 and 0.766). The mean DW volume was 30.48?±?22.41 cm³. DW volumes were not significantly different from FDG PET volumes at either 35 % SUV_max or 40 % SUV_max or from T2-W imaging volumes (P?>?0.05). PET subvolumes with increasing SUV_max cut-off percentage showed an inverse change in mean ADC values on DW imaging (P?<?0.001, ANOVA).

Conclusion

Hybrid PET/MR showed strong volume concordance between FDG PET, and T2-W and DW imaging in cervical cancer. Cut-off at 35 % or 40 % of SUV_max is recommended for ¹⁸F-FDG PET/MR SUV-based tumour volume estimation. The linear tumour subvolume concordance between FDG PET and DW imaging demonstrates individual regional concordance of metabolic activity and cell density.     

18F-FDG-PET/CT predicts survival in hypopharyngeal squamous cell carcinoma

Objectives

We investigated the relationship between overall survival of patients and pretreatment [¹⁸F]-2-fluorodeoxyglucose (¹⁸F-FDG) uptake, assessed by positron emission tomography combined with computed tomography (PET/CT) in hypopharyngeal squamous cell carcinoma.

Methods

Thirty-one patients who were newly diagnosed as resectable hypopharyngeal squamous cell carcinoma underwent pretreatment ¹⁸F-FDG-PET/CT. We used the maximum standardized uptake value (SUVmax) as ¹⁸F-FDG uptake. Overall survival rate was calculated by the Kaplan–Meier method.

Results

The median SUVmax was 11.53 (range 2.49–22.33). Patients with SUVmax ≥ 13 significantly exhibited shorter overall survival in univariate analysis (p < 0.01). Moreover, by Cox proportional hazards model of multivariate analysis, SUVmax ≥ 13 was a significant prognostic factor independent of clinical T and N classification, and treatment group (p < 0.02).

Conclusions

These results suggested that SUVmax obtained by pretreatment ¹⁸F-FDG PET/CT assessment is an important prognostic factor in patients with hypopharyngeal squamous cell carcinoma.     

Heritability, determinants and reference values of renal length: a family-based population study

Objectives

In this population-based study, reference values were generated for renal length, and the heritability and factors associated with kidney length were assessed.

Methods

Anthropometric parameters and renal ultrasound measurements were assessed in randomly selected nuclear families of European ancestry (Switzerland). The adjusted narrow sense heritability of kidney size parameters was estimated by maximum likelihood assuming multivariate normality after power transformation. Gender-specific reference centiles were generated for renal length according to body height in the subset of non-diabetic non-obese participants with normal renal function.

Results

We included 374 men and 419 women (mean ± SD, age 47?±?18 and 48?±?17 years, BMI 26.2?±?4 and 24.5?±?5 kg/m², respectively) from 205 families. Renal length was 11.4?±?0.8 cm in men and 10.7?±?0.8 cm in women; there was no difference between right and left renal length. Body height, weight and estimated glomerular filtration rate (eGFR) were positively associated with renal length, kidney function negatively, age quadratically, whereas gender and hypertension were not. The adjusted heritability estimates of renal length and volume were 47.3?±?8.5 % and 45.5?±?8.8 %, respectively (P?<?0.001).

Conclusion

The significant heritability of renal length and volume highlights the familial aggregation of this trait, independently of age and body size. Population-based references for renal length provide a useful guide for clinicians.

Key Points

? Renal length and volume are heritable traits, independent of age and size. ? Based on a European population, gender-specific reference values/percentiles are provided for renal length. ? Renal length correlates positively with body length and weight. ? There was no difference between right and left renal lengths in this study. ? This negates general teaching that the left kidney is larger and longer.     

Clinical validation of semi-automated software for volumetric and dynamic contrast enhancement analysis of soft tissue venous malformations on Magnetic Resonance Imaging examination

Objectives

To evaluate venous malformation (VM) volume and contrast-enhancement analysis on magnetic resonance imaging (MRI) compared with diameter evaluation.

Methods

Baseline MRI was undertaken in 44 patients, 20 of whom were followed by MRI after sclerotherapy. All patients underwent short-tau inversion recovery (STIR) acquisitions and dynamic contrast assessment. VM diameters in three orthogonal directions were measured to obtain the largest and mean diameters. Volumetric reconstruction of VM was generated from two orthogonal STIR sequences and fused with acquisitions after contrast medium injection. Reproducibility (interclass correlation coefficients [ICCs]) of diameter and volume measurements was estimated. VM size variations in diameter and volume after sclerotherapy and contrast enhancement before sclerotherapy were compared in patients with clinical success or failure.

Results

Inter-observer ICCs were similar for diameter and volume measurements at baseline and follow-up (range 0.87–0.99). Higher percentages of size reduction after sclerotherapy were observed with volume (32.6?±?30.7 %) than with diameter measurements (14.4?±?21.4 %; P?=?0.037). Contrast enhancement values were estimated at 65.3?±?27.5 % and 84?±?13 % in patients with clinical failure and success respectively (P?=?0.056).

Conclusions

Venous malformation volume was as reproducible as diameter measurement and more sensitive in detecting therapeutic responses. Patients with better clinical outcome tend to have stronger malformation enhancement.

Key points

? Magnetic resonance imaging readily demonstrates diameters and volumes of venous malformations ? MRI diameter calculations are reproducible in estimating the size of venous malformations ? But volumetric models of malformations are more sensitive in detecting therapeutic response ? Dynamic enhancement is also better assessed with automated volumetric software ? Volumetric analysis of malformations offers promise to guide therapy and assess response