MR imaging of renal cortical tumours: qualitative and quantitative chemical shift imaging parameters

Objectives

To assess qualitative and quantitative chemical shift MRI parameters of renal cortical tumours.

Methods

A total of 251 consecutive patients underwent 1.5-T MRI before nephrectomy. Two readers (R1, R2) independently evaluated all tumours visually for a decrease in signal intensity (SI) on opposed- compared with in-phase chemical shift images. In addition, SI was measured on in- and opposed-phase images (SI^IP, SI^OP) and the chemical shift index was calculated as a measure of percentage SI change. Histopathology served as the standard of reference.

Results

A visual decrease in SI was identified significantly more often in clear cell renal cell carcinoma (RCCs) (R1, 73 %; R2, 64 %) and angiomyolipomas (both, 80 %) than in oncocytomas (29 %, 12 %), papillary (29 %, 17 %) and chromophobe RCCs (13 %, 9 %; all, P?<?0.05). Median chemical shift index was significantly greater in clear cell RCC and angiomyolipoma than in the other histological subtypes (both, P?<?0.001). Interobserver agreement was fair for visual (kappa, 0.4) and excellent for quantitative analysis (concordance correlation coefficient, 0.80).

Conclusions

A decrease in SI on opposed-phase chemical shift images is not an identifying feature of clear cell RCCs or angiomyolipomas, but can also be observed in oncocytomas, papillary and chromophobe RCCs. After excluding angiomyolipomas, a decrease in SI of more than 25 % was diagnostic for clear cell RCCs.

Key Points

? Chemical shift MRI offers new information about fat within renal tumours. ? Opposed-phase signal decrease can be observed in all renal cortical tumours. ? A greater than 25 % decrease in signal appears to be diagnostic for clear cell RCCs     

Locally advanced rectal cancer: diffusion-weighted MR tumour volumetry and the apparent diffusion coefficient for evaluating complete remission after preoperative chemoradiation therapy

Objective

To evaluate DW MR tumour volumetry and post-CRT ADC in rectal cancer as predicting factors of CR using high b values to eliminate perfusion effects.

Methods

One hundred rectal cancer patients who underwent 1.5-T rectal MR and DW imaging using three b factors (0, 150, and 1,000 s/mm²) were enrolled. The tumour volumes of T2-weighted MR and DW images and pre- and post-CRT ADC_150–1000 were measured. The diagnostic accuracy of post-CRT ADC, T2-weighted MR, and DW tumour volumetry was compared using ROC analysis.

Results

DW MR tumour volumetry was superior to T2-weighted MR volumetry comparing the CR and non-CR groups (P?<?0.001). Post-CRT ADC showed a significant difference between the CR and non-CR groups (P?=?0.001). The accuracy of DW tumour volumetry (A_z?=?0.910) was superior to that of T2-weighed MR tumour volumetry (A_z?=?0.792) and post-CRT ADC (A_z?=?0.705) in determining CR (P?=?0.015). Using a cutoff value for the tumour volume reduction rate of more than 86.8 % on DW MR images, the sensitivity and specificity for predicting CR were 91.4 % and 80 %, respectively.

Conclusion

DW MR tumour volumetry after CRT showed significant superiority in predicting CR compared with T2-weighted MR images and post-CRT ADC.

Key Points

? Diffusion-weighted MR (DWMR) imaging offers new information about rectal cancer. ? DWMR helps to predict complete remission after chemoradiotherapy in patients with advanced rectal cancer. ? DWMR provides more accurate diagnostic information than T2-weighted MRI. ? Apparent diffusion coefficients can predict CR, but they have certain clinical limitations.     

Pretherapy metabolic tumour volume is an independent predictor of outcome in patients with diffuse large B-cell lymphoma

Purpose

We investigated the prognostic value of total metabolic tumour volume (TMTV) in diffuse large B-cell lymphoma (DLBCL).

Methods

TMTV was measured in 114 patients with newly diagnosed DLBCL who underwent ¹⁸F-FDG PET/CT at baseline before immunochemotherapy. TMTV was computed by summing the volumes of all lymphomatous lesions after applying the local SUVmax threshold of 41 % using semiautomatic software. Prognostic value was assessed by Kaplan-Meier estimates of progression-free survival (PFS) and overall survival (OS).

Results

Median follow-up was 39 months. Average pretherapy TMTV was 509?±?568 cm³. The 3-year estimates of PFS were 77 % in the low metabolic burden group (TMTV ≤550 cm³) and 60 % in the high metabolic burden group (TMTV >550 cm³, p?=?0.04), and prediction of OS was even better (87 % vs. 60 %, p?=?0.0003). Cox regression showed independence of TMTV for OS prediction (p?=?0.002) compared with other pretherapy indices of tumour burden, such as tumour bulk and the International Prognostic Index.

Conclusion

Pretherapy TMTV is an independent predictor of outcome in patients with DLBCL.     

Apparent diffusion coefficient modifications in assessing gastro-oesophageal cancer response to neoadjuvant treatment: comparison with tumour regression grade at histology

Objectives

To assess changes in apparent diffusion coefficient (ΔADC) and volume (ΔV) after neoadjuvant treatment (NT), and tumour regression grade (TRG) in gastro-oesophageal cancers (GEC), and to discriminate responders from non-responders.

Methods

Thirty-two patients with biopsy-proven locally-advanced GEC underwent diffusion weighted magnetic resonance imaging (DWI) pre- and post-NT. Lesion ADC, volume, ΔADC and ΔV were calculated. TRG 1-2-3 patients were classified as R; TRG 4-5 as non-responders. ΔADC-TRG and ΔV-TRG correlations, pre-NT and post-NT ADC, ΔADC and ΔV cut-off values for responders and non-responders were calculated. Two readers measured mean tumour ADCs and interobserver variability was calculated. (Spearman’s and intraclass correlation coefficient [ICC]).

Results

The interobserver reproducibility was very good both for pre-NT (Spearman’s rho?=?0.8160; ICC?=?0.8993) and post-NT (Spearman’s rho?=?0.8357; ICC?=?0.8663). Responders showed lower pre-NT ADC (1.32 versus 1.63?×?10^?3?mm²/s; P?=?0.002) and higher post-NT ADC (2.22 versus 1.51?×?10^?3?mm²/s; P?=?0.001) than non-responders and ADC increased in responders (ΔADC, 85.45 versus ?8.21 %; P?=?0.00005). ΔADC inversely correlated with TRG (r?=??0.71, P?=?0.000004); no difference in ΔV between responders and non-responders (?50.92 % versus ?14.12 %; P?=?0.068) and no correlation ΔV-TRG (r?=?0.02 P?=?0.883) were observed.

Conclusions

The ADC can be used to assess gastro-oesophageal tumour response to neoadjuvant treatment as a reliable expression of tumour regression.

Key Points

? DWI is now being used to assess many cancers. ? Change in ADC measurements offer new information about oesophageal tumours. ? ADC changes are more reliable than dimensional criteria in assessing neoadjuvant treatment. ? Such ADC assessment could optimise management of locally advanced gastro-oesophageal cancers.     

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.     

Blood oxygenation level-dependent MR imaging as a predictor of therapeutic response to concurrent chemoradiotherapy in cervical cancer: a preliminary experience

Objectives

To investigate the value of blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) as a predictor of therapeutic response in cervical cancer patients undergoing concurrent chemoradiotherapy (CCRT).

Methods

Thirty consecutive patients with biopsy-proven cervical cancer were examined by BOLD MRI before (preTx) and after CCRT (postTx). The R2* value (s^-1) was calculated in the tumour and normal myometrium for preTx and postTx studies. Final tumour responses, as determined by changes of tumour size or volume on MRI, were correlated with tumour R2* values at preTx.

Results

The mean R2* values of tumours at preTx (21.1) were significantly lower than those at postTx (39.4 s^-1) (p?<?0.001), while those of normal myometrium were similar between preTx and postTx (p?=?0.363). At preTx, tumour R2* values showed significantly negative correlation with final tumour size response (p?=?0.022, Spearman’s coefficient?=?-0.415). However, tumour R2* values at preTx were not associated with final tumour volume response (p?=?0.069).

Conclusions

BOLD MRI at 3 T, as an imaging biomarker, may have the potential to evaluate therapeutic response in cervical cancers. The association between BOLD MRI findings and CCRT responses warrants further validation.

Key points

? Hypoxia in cervical cancer is an independent risk factor ? BOLD MRI reflect oxygenation status of tissue adjacent to perfused microvessels ? Pretreatment tumour R2* reveal negative correlation with final tumour size response ? Accurate oxygenation assessment in cervical cancer may help clinical decision making     

Meta-analysis: diagnostic accuracy of coronary CT angiography with prospective ECG gating based on step-and-shoot,Flash and volume modes for detection of coronary artery disease

Objectives

To investigate the diagnostic performance of coronary computed tomographic angiography (CCTA) with prospective electrocardiograph (ECG) gating based on step-and-shoot (SAS), Flash and volume imaging modes.

Methods

We searched the electronic databases PubMed for all published studies regarding CCTA. We used an exact binomial rendition of the bivariate mixed-effects regression model developed for synthesis of diagnostic data.

Results

A total of 21,852 segments, 4,851 vessels and 1,375 patients were identified using database searches. Patient-level pooled sensitivity was 0.99 (95 % confidence interval [CI], 0.98–1.00); specificity was 0.88 (CI, 0.85–0.91). The results showed that the sensitivity and specificity for detection of significant stenosis did not differ in the three protocols (P?=?0.24). No heterogeneity was found at the patient level for sensitivity (Q?=?26.23; P?=?0.12; I ²?=?27.56 % [CI, 0.00-67.02 %]) and specificity (Q?=?19.54; P?=?0.42; I ²?=?2.78 % [CI, 0.00-66.26 %]).

Conclusions

CCTA with prospective ECG gating has similar high diagnostic value to rule out CAD in all three presented modes.

Key Points

? The accuracy of CCTA with different prospective ECG gating is similar ? CCTA with prospective ECG gating is effective to exclude coronary artery disease ? The radiation dose of volume mode increases with higher heart rate     

Variability of 18F-FDG-positive lung lesion volume by thresholding

Objectives

To assess the variability of ¹⁸F-FDG-positive volume measurements in lung cancer patients, obtained with different fixed percentages of maximum standard uptake value (SUVmax) thresholds.

Methods

PET dynamic acquisition involving ten frames was performed within 60–110 min post-injection in eight patients. In each lesion (n?=?11), volume was automatically outlined in each frame with fixed 40–50–60–70 % of the SUVmax thresholds. Thus, ten volume values for each threshold (V_{40–50–60–70}) were available to calculate relative SD (SDr), and hence relative measurement error (MEr) and repeatability (R). Dependence on SUVmax variability was also assessed.

Results

Mean SDr (<SDr>; %) of volume estimates was found to strongly correlate with threshold value (T; %): <SDr>?= 1.626?×?exp(0.044?×?T) (r?=?0.999; P?<?0.01). MEr and R for V₄₀ were found to be (95 % CL) 18.9 % and 26.7 %. For all fixed thresholds, in successive frames of an arbitrary lesion, volume estimate inversely correlated with SUVmax (P?≤?0.02).

Conclusions

A formula allows estimation of the variability of ¹⁸F-FDG-positive volumes provided by any fixed percentage of SUVmax threshold, and hence by any thresholding method. It only necessitates conversion of the threshold value into the SUVmax percentage in order to aid quick estimation of volume variability magnitude in current clinical practice.

Key Points

? In oncology, PET is widely used to assess the metabolic active volume ? This paper investigates the variability of ¹⁸ F-FDG-positive volumes by thresholding ? A formula is available for estimating this variability for any thresholding method ? For 40 %-SUVmax threshold, measurement error and repeatability are (95 % CL) 18.9 %/26.7 %     

Helical CT-enteroclysis in the detection of small-bowel tumours: a meta-analysis

Objective

To perform a meta-analysis to determine sensitivity and specificity estimates of helical CT-enteroclysis in the detection of small-bowel tumours.

Methods

A search for relevant articles published from January 1992 to November 2010 was performed. Study design, patient characteristics and 2?×?2 contingency tables were recorded for eligible studies. Heterogeneity was assessed with the I ² statistic. A bivariate generalised linear random-effects model was used to summarise sensitivity and specificity estimates for small-bowel tumour detection on a per-patient basis. Sensitivity and specificity estimates were compared in different subgroups.

Results

Twelve studies (696 patients) were eligible. The mean small-bowel tumour prevalence was 22.6 % (range 7.7–45.8 %). Inter-study heterogeneity was substantial for sensitivity (I ²?=?66.9 %; 95 % CI 28.7–88.5 %) and low for specificity (I ²?=?10.6 %; 95 % CI 0.0–55.0 %). On a per-patient basis, pooled sensitivity was 92.8 % (95 % CI 71.3–98.5 %) and pooled specificity 99.2 % (95 % CI 94.2–99.9 %) for the diagnosis of small-bowel tumour. Subgroup analysis revealed that small-bowel preparation, more than one imaging pass and large volumes (≥2 L) of enteral contrast agent did not improve tumour detection.

Conclusion

Our meta-analysis confirms that helical CT-enteroclysis has high degrees of sensitivity and specificity for small-bowel tumour detection. However, our findings reinforce the need for more standardised individual studies.

Key Points

? Helical CT-enteroclysis is highly sensitive for the diagnosis of small-bowel tumours. ? Helical CT-enteroclysis is highly specific for the diagnosis of small-bowel tumours, ? Helical CT-enteroclysis can be used as a first-line investigation. ? A single enteric phase examination provides optimal tumour detection.     

Influence of imaging and histological factors on prostate cancer detection and localisation on multiparametric MRI: a prospective study

Objectives

To assess factors influencing prostate cancer detection on multiparametric (T2-weighted, diffusion-weighted, and dynamic contrast-enhanced) MRI.

Methods

One hundred and seventy-five patients who underwent radical prostatectomy were included. Pre-operative MRI performed at 1.5 T (n?=?71) or 3 T (n?=?104), with (n?=?58) or without (n?=?117) an endorectal coil were independently interpreted by two radiologists. A five-point subjective suspicion score (SSS) was assigned to all focal abnormalities (FAs). MR findings were then compared with whole-mount sections.

Results

Readers identified 192–214/362 cancers, with 130–155 false positives. Detection rates for tumours of <0.5 cc (cm³), 0.5–2 cc and >2 cc were 33–45/155 (21–29 %), 15–19/35 (43–54 %) and 8–9/12 (67–75 %) for Gleason ≤6, 17/27 (63 %), 42–45/51 (82–88 %) and 34/35 (97 %) for Gleason 7 and 4/5 (80 %), 13/14 (93 %) and 28/28 (100 %) for Gleason ≥8 cancers respectively. At multivariate analysis, detection rates were influenced by tumour Gleason score, histological volume, histological architecture and location (P?<?0.0001), but neither by field strength nor coils used for imaging. The SSS was a significant predictor of both malignancy of FAs (P?<?0.005) and aggressiveness of tumours (P?<?0.00001).

Conclusions

Detection rates were significantly influenced by tumour characteristics, but neither by field strength nor coils used for imaging. The SSS significantly stratified the risk of malignancy of FAs and aggressiveness of detected tumours.

Key Points

? Prostate cancer volume, Gleason score, architecture and location are MRI predictors of detection. ? Field strength and coils used do not influence the tumour detection rate. ? Multiparametric MRI is accurate for detecting aggressive tumours. ? A subjective suspicion score can stratify the risk of malignancy and tumour aggressiveness.     

PET-based delineation of tumour volumes in lung cancer: comparison with pathological findings

Purpose

The objective of the study was to validate an adaptive, contrast-oriented thresholding algorithm (COA) for tumour delineation in ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for non-small cell lung cancer (NSCLC) in comparison with pathological findings. The impact of tumour localization, tumour size and uptake heterogeneity on PET delineation results was also investigated.

Methods

PET tumour delineation by COA was compared with both CT delineation and pathological findings in 15 patients to investigate its validity. Correlations between anatomical volume, metabolic volume and the pathology reference as well as between the corresponding maximal diameters were determined. Differences between PET delineations and pathological results were investigated with respect to tumour localization and uptake heterogeneity.

Results

The delineated volumes and maximal diameters measured on PET and CT images significantly correlated with the pathology reference (both r?>?0.95, p?<?0.0001). Both PET and CT contours resulted in overestimation of the pathological volume (PET 32.5?±?26.5 %, CT 46.6?±?27.4 %). CT volumes were larger than those delineated on PET images (CT 60.6?±?86.3 ml, PET 48.3?±?61.7 ml). Maximal tumour diameters were similar for PET and CT (51.4?±?19.8 mm for CT versus 53.4?±?19.1 mm for PET), slightly overestimating the pathological reference (mean difference CT 4.3?±?3.2 mm, PET 6.2?±?5.1 mm). PET volumes of lung tumours located in the lower lobe were significantly different from those determined from pathology (p?=?0.037), whereas no significant differences were observed for tumours located in the upper lobe (p?=?0.066). Only minor correlation was found between pathological tumour size and PET heterogeneity (r?=??0.24).

Conclusion

PET tumour delineation by COA showed a good correlation with pathological findings. Tumour localization had an influence on PET delineation results. The impact of tracer uptake heterogeneity on PET delineation should be considered carefully and individually in each patient. Altogether, PET tumour delineation by COA for NSCLC patients is feasible and reliable with the potential for routine clinical application.     

Improved Hypertrophy of Future Remnant Liver after Portal Vein Embolization with Plugs,Coils and Particles

Purpose

To retrospectively analyze efficacy as measured by volume gain of future remnant liver (FRL) after right portal vein embolization (PVE) using particles only versus particles and additional central plug and/or coil (CP/C) embolization.

Methods

All patients who underwent PVE between July 2011 and December 2012 were retrospectively analyzed. Right PVE was performed either with particle-only (PO) embolization or additional CP/C embolization. All enrolled patients underwent computed tomography or magnetic resonance imaging before PVE and surgery. The images were used for volumetry of the FRL.

Results

Of 75 patients, 40 had PO and 35 CP/C embolization. Age, sex, and tumor entities did not differ significantly between the two groups. Tumor entities included cholangiocarcinoma (n = 52), metastasis from colorectal cancer (n = 14), hepatocellular carcinoma (n = 2), and others (n = 7). Time from PVE to preoperative imaging was similar in both groups. FRL volume before PVE was 329 ± 121 ml in the PO group and 333 ± 135 ml in the CP/C group, and 419 ± 135 ml and 492 ± 165 ml before operation. The average percentage volume gain was significantly higher in the CP/C group than in the PO group, with 53.3 ± 34.5 % versus 30.9 ± 28.8 % (p = 0.002).

Conclusion

Right PVE with additional CP/C embolization leads to a significantly higher gain in FRL volume than embolization with particles alone.     

Texture analysis of <Superscript>18</Superscript>F-FDG PET/CT to predict tumour response and prognosis of patients with esophageal cancer treated by chemoradiotherapy

Purpose

This retrospective study was done to examine whether the heterogeneity in primary tumour F-18-fluorodeoxyglucose (¹⁸F-FDG) distribution can predict tumour response and prognosis of patients with esophageal cancer treated by chemoradiotherapy (CRT).

Methods

The enrolled 52 patients with esophageal cancer underwent ¹⁸F-FDG-PET/CT studies before CRT. SUVmax, SUVmean, metabolic tumour volume (MTV, SUV?≥?2.5), total lesion glycolysis (TLG) and six heterogeneity parameters assessed by texture analysis were obtained. Patients were classified as responders or non-responders according to Response Evaluation Criteria in Solid Tumors. Progression-free survival (PFS) and overall survival (OS) were calculated by the Kaplan–Meier method. Prognostic significance was assessed by Cox proportional hazards analysis.

Results

Thirty four non-responders showed significantly higher MTV (p?=?0.006), TLG (p?=?0.007), intensity variability (IV; p?=?0.003) and size-zone variability (SZV; p?=?0.004) than 18 responders. The positive and negative predictive values for non-responders were 77 % and 69 % in MTV, 76 % and 100 % in TLG, 78 % and 67 % in IV and 78 % and 82 % in SZV, respectively. Although PFS and OS were significantly shorter in patients with high MTV (PFS, p?=?0.018; OS, p?=?0.014), TLG (PFS, p?=?0.009; OS, p?=?0.025), IV (PFS, p?=?0.013; OS, p?=?0.007) and SZV (PFS, p?=?0.010; OS, p?=?0.007) at univariate analysis, none of them was an independent factor, while lymph node status, stage and tumour response status were independent factors at multivariate analysis.

Conclusion

Texture features IV and SZV, and volumetric parameters MTV and TLG can predict tumour response, but all of them have limited value in prediction of prognosis of patients with esophageal cancer treated by CRT.

     

Morphological, functional and metabolic imaging biomarkers: assessment of vascular-disrupting effect on rodent liver tumours

Objectives

To evaluate effects of a vascular-disrupting agent on rodent tumour models.

Methods

Twenty rats with liver rhabdomyosarcomas received ZD6126 intravenously at 20 mg/kg, and 10 vehicle-treated rats were used as controls. Multiple sequences, including diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) with the microvascular permeability constant (K), were acquired at baseline, 1 h, 24 h and 48 h post-treatment by using 1.5-T MRI. [¹⁸F]fluorodeoxyglucose micro-positron emission tomography (¹⁸F-FDG µPET) was acquired pre- and post-treatment. The imaging biomarkers including tumour volume, enhancement ratio, necrosis ratio, apparent diffusion coefficient (ADC) and K from MRI, and maximal standardised uptake value (SUV_max) from FDG µPET were quantified and correlated with postmortem microangiography and histopathology.

Results

In the ZD6126-treated group, tumours grew slower with higher necrosis ratio at 48 h (P?<?0.05), corresponding well to histopathology; tumour K decreased from 1 h until 24 h, and partially recovered at 48 h (P?<?0.05), parallel to the evolving enhancement ratios (P?<?0.05); ADCs varied with tumour viability and perfusion; and SUV_max dropped at 24 h (P?<?0.01). Relative K of tumour versus liver at 48 h correlated with relative vascular density on microangiography (r?=?0.93, P?<?0.05).

Conclusions

The imaging biomarkers allowed morphological, functional and metabolic quantifications of vascular shutdown, necrosis formation and tumour relapse shortly after treatment. A single dose of ZD6126 significantly diminished tumour blood supply and growth until 48 h post-treatment.     

Comparative diagnostic accuracy of contrast-enhanced MRI and 18F-FDOPA PET-CT in recurrent glioma

Objectives

To compare the diagnostic accuracy of contrast enhanced magnetic resonance imaging (Ce-MRI) and ¹⁸F-fluorodopa (¹⁸F-FDOPA) positron emission tomography (PET)-computed tomography (CT) for detecting recurrent glioma.

Methods

In this prospective study, 35 patients (age, 36.62?±?0.86 years; 80 % male) with histopathologically proven glioma with clinical suspicion of recurrence were evaluated using Ce-MRI and ¹⁸F-FDOPA PET-CT. ¹⁸F-FDOPA PET-CT images were evaluated qualitatively and semi-quantitatively. Combination of clinical follow-up (minimum 1 year), repeat imaging and/or biopsy (when available) was taken as the reference standard.

Results

Based on the reference standard, 26 patients were positive and nine were negative for recurrence. The sensitivity, specificity and accuracy of Ce-MRI were 92.3 %, 44.4 % and 80 % respectively, whereas those of ¹⁸F-FDOPA PET-CT were 100 %, 88.89 % and 97.1 % respectively. Results of Ce-MRI and ¹⁸F-FDOPA PET-CT were concordant in 74.3 % (29/35) and discordant in 17.1 % of patients (6/35). On McNemar analysis the difference was not statistically significant overall (P?=?0.687), for high-grade tumour (P?=?0.5) or low-grade tumours (P?=?1.0). However, ¹⁸F-FDOPA PET-CT was more specific than Ce-MRI overall (P?=?0.0002), for high-grade tumour (P?=?0.006) and low-grade tumours (P?=?0.004).

Conclusion

F-FDOPA PET-CT shows a high but comparable diagnostic accuracy to Ce-MRI for the detection of recurrent glioma. However, it is more specific than Ce-MRI.

Key Points

? Recurrent glioma in the postoperative site remains a diagnostic dilemma. ? ¹⁸ F-FDOPA PET-CT shows high diagnostic accuracy for detecting recurrent glioma. ? Diagnostic accuracies for ¹⁸ F-FDOPA PET-CT and contrast enhanced MRI are comparable. ? However, ¹⁸ F-FDOPA PET-CT is more specific than Ce-MRI for recurrent glioma.     

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.     

Interscan reproducibility of quantitative coronary plaque volume and composition from CT coronary angiography using an automated method

Objectives

Quantitative measurements of coronary plaque volume may play a role in serial studies to determine disease progression or regression. Our aim was to evaluate the interscan reproducibility of quantitative measurements of coronary plaque volumes using a standardized automated method.

Methods

Coronary dual source computed tomography angiography (CTA) was performed twice in 20 consecutive patients with known coronary artery disease within a maximum time difference of 100 days. The total plaque volume (TP), the volume of non-calcified plaque (NCP) and calcified plaque (CP) as well as the maximal remodelling index (RI) were determined using automated software.

Results

Mean TP volume was 382.3?±?236.9 mm³ for the first and 399.0?±?247.3 mm³ for the second examination (p?=?0.47). There were also no significant differences for NCP volumes, CP volumes or RI. Interscan correlation of the plaque volumes was very good (Pearson’s correlation coefficients: r?=?0.92, r?=?0.90 and r?=?0.96 for TP, NCP and CP volumes, respectively).

Conclusions

Automated software is a time-saving method that allows accurate assessment of coronary atherosclerotic plaque volumes in coronary CTA with high reproducibility. With this approach, serial studies appear to be possible.

Key Points

? Reproducibility of coronary atherosclerotic plaque volume in coronary CTA is high. ? Using automated software facilitates quantitative measurements. ? Serial studies to determine progression or regression of coronary plaque are possible.     

Stability of ischemic core volume during the initial hours of acute large vessel ischemic stroke in a subgroup of mechanically revascularized patients

Introduction

This study aimed to relate growth of the infarct core with time to recanalization in patients receiving mechanical recanalization in whom the time of recanalization is known.

Methods

We analyzed data from patients with anterior circulation acute ischemic stroke who underwent mechanical recanalization. Demographic and angiographic characteristics, initial apparent diffusion coefficient (ADC) infarct volume, time-to-peak defect volume, revascularization grade, 24–48 h nonenhanced computed tomography (CT) infarct volume, symptom onset to recanalization time, diffusion-weighted imaging to recanalization time, and discharge National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores were compared between minimal and substantial infarct growth groups. Substantial infarct growth was defined as an increase of infarct volume >10 cm³ assessed by subtracting initial ADC infarct core volume from infarct volume at 24–48 h CT.

Results

Of 25 patients, 9 had minimal infarct growth (median 0 cm³, interquartile range (IQR) ?3 to 5 cm³) and 16 had substantial infarct growth (median 103 cm³, IQR 48–132 cm³). Patients with minimal infarct growth had a median time from symptom onset to recanalization of 329 min (IQR 314–412 min) and a median time from imaging to recanalization of 231 min (IQR 198–309 min). On univariate analysis, minimal infarct growth was related to male gender (p?=?0.04), smaller initial ADC volume (p?=?0.04), higher recanalization grade (p?<?0.001), and lower discharge NIHSS (p?=?0.04) and mRS grades (p?=?0.04).

Conclusion

There was no or minimal infarct core growth in at least one third of patients despite an exceptionally long median time from magnetic resonance imaging to recanalization of almost 4 h.     

Nitroglycerine use in transcatheter arterial (chemo)embolization in patients with hepatocellular carcinoma and dual-energy CT assessment of Lipiodol retention

Objectives

To investigate whether the addition of nitroglycerine to transcatheter arterial (chemo)embolization (TAE/TACE) can increase the delivery and effectiveness of TAE/TACE in patients with hepatocellular carcinoma (HCC) by dual-energy CT.

Methods

HCC patients (BCLC stage A or B) were randomized to (n?=?51) or not to (n?=?50) receive nitroglycerine and an emulsion of Lipiodol with or without doxorubicin, followed by embolization with Gelfoam pledgets. Dual-energy CT was performed pre- and 1 to 3?months post-embolization to assess changes in tumour diameter and Lipiodol levels in tumours.

Results

Median tumour diameter decreased from baseline in both groups with and without nitroglycerine (7.11?% vs. 12.5?%, respectively), and was statistically significant in the group receiving nitroglycerine (P?=?0.023). There was no difference between the two groups in disease response (P?=?0.237). The concentration and percentage of Lipiodol retained in tumours were significantly greater in patients treated with nitroglycerine compared to those without (median concentration 15.05?mg/mL vs. 4.40?mg/mL, respectively, P?P?Conclusions Nitroglycerine increased delivery of the Lipiodol emulsion via TAE/TACE to HCC tumours with significant tumour reduction. Dual-energy CT can accurately quantify the amount of Lipiodol deposited in tumours.

Key Points

? Nitroglycerine improves delivery of tumour-targeted therapy via enhanced permeability and retention. ? In hepatocellular carcinoma, nitroglycerine added to TAE/TACE showed greater tumour reduction. ? Dual-energy CT can reliably quantify the amount of Lipiodol in TAE/TACE.     

18F-FDG PET/CT-based treatment response evaluation in locally advanced rectal cancer: a prospective validation of long-term outcomes

Purpose

To prospectively evaluate the usefulness of ¹⁸F-FDG PET/CT) imaging for predicting histopathological response and long-term clinical outcomes in locally advanced rectal cancer (LARC).

Methods

This prospective study included 38 patients with a confirmed diagnosis of LARC (cT3-4 or cN+) who underwent ¹⁸F-FDG PET/CT before and after neoadjuvant therapy (NAT). Total mesorectal excision was scheduled 6 weeks after NAT and was followed by an expert histopathological analysis of the surgical specimen. Baseline variables and previously identified maximum FDG standardized uptake value (SUVmax) cut-off values before NAT (SUVmax_PRE ≥6) and after NAT (SUVmax_POST ≥2), and the absolute and percentage reductions from baseline SUVmax (?SUVmax <4 and ?SUVmax% <65 %, respectively) were applied to differentiate patients showing a metabolic tumour response from nonresponders. These features were correlated with tumour regression grade (TRG), disease-free survival (DFS) and overall survival (OS).

Results

Significantly higher 5-year DFS and OS were seen in 19 responders (TRG 3 or 4) than in 19 nonresponders (TRG 0–2; 94.4 vs. 48.8 %, p?=?0.001; 94.7 vs. 63.2 %, p?=?0.02, respectively). In multivariate analysis the only PET/CT SUVmax-based parameter significantly correlated with the likelihood of recurrence and survival was ?SUV% <65 % (HR?=?5.95, p?=?0.02, for DFS; HR?=?5.26, p?=?0.04, for OS)

Conclusion

This prospective study proved that ¹⁸F-FDG PET/CT is a valuable imaging tool for assessing rectal cancer TRG and long-term prognosis, and could potentially serve as an intermediate endpoint in treatment optimization research and rectal cancer patient care.