Value of diffusion-weighted imaging to detect small malignant pelvic lymph nodes at 3 T

Objective

To investigate the usefulness of diffusion-weighted imaging (DWI) to discriminate between metastatic and non-metastatic small lymph nodes in pelvic carcinoma.

Materials and Methods

A total of 259 patients (180 normal, 79 metastatic) prospectively underwent DWI at 3 T. We measured the short-axis diameter and the mean apparent diffusion coefficient (ADC) value. Lymph nodes with a short-axis diameter larger than 8 mm were recorded as being suspected metastatic lymph nodes. Imaging data were correlated station by station with histopathological results.

Results

A total of 140 metastatic nodes were accurately matched with histology. On T2w, the short-axis diameter for non-metastatic and metastatic lymph nodes was 6.4 mm?±?2.5 mm and 8.3 mm?±?4.5 mm, respectively. Almost all metastatic or non-metastatic nodes had similar high signal intensity on DWI (except in 5 cases) with a homogeneous pattern. The mean ADC values (10^?3 mm³/s ± standard deviation) of involved lymph nodes, control iliac nodes and control inguinal nodes were 924?±?217, 968?±?182 and 1,036?±?181, respectively. There were no statistically significant differences in the ADC of metastatic and non-metastatic nodes.

Conclusion

Isolated measurement of mean ADC values in a suspected station does not contribute to the diagnosis of metastatic nodes, in patients with small ambiguous nodes.     

Dual-phase dual-energy CT in patients with lung cancer: assessment of the additional value of iodine quantification in lymph node therapy response

Objectives

To investigate the potential contribution of iodine uptake calculation from dual-phase dual-energy CT (DE-CT) for lymph node staging and therapy response monitoring in lung cancer patients.

Methods

Retrospective analysis of 27 patients with non-small cell lung carcinoma (NSCLC), who underwent dual-phase DE-CT before and after chemotherapy, was performed. Iodine uptake (mg/mL) and total iodine uptake (mg) were calculated using prototype software in the early (arterial) and late (venous) post-contrast circulatory phase in 110 mediastinal lymph nodes. The arterial enhancement fraction (AEF) was calculated and compared with lymph node size and response to chemotherapy.

Results

A significant difference of AEF was observed between enlarged (90.4 %; 32.3–238.5 %) and non-enlarged (72.7 %; ?37.5-237.5 %) lymph nodes (p?=?0.044) before treatment onset. A significantly different change of AEF in responding (decrease of 26.3 %; p?=?0.022) and non-responding (increase of 43.0 %; p?=?0.031) lymph nodes was demonstrated. A higher value of AEF before treatment was observed in lymph nodes with subsequent favourable response (88.6 % vs. 77.7 %; p?=?0.122), but this difference did not reach statistical significance.

Conclusions

The dual-phase DE-CT examination with quantification of ratio of early and late post-contrast iodine uptake is a feasible and promising method for the functional evaluation of mediastinal lymph nodes including therapy response assessment.

Key Points

? Dual-phase DE-CT is beneficial for mediastinal lymph node assessment in NSCLC. ? Arterial to venous iodine uptake ratio was higher in enlarged lymph nodes. ? Change of arterial enhancement fraction correlated to therapy response.     

ADC maps in the prediction of pelvic lymph nodal metastatic regions in endometrial cancer

Objectives

To evaluate the usefulness of apparent diffusion coefficient (ADC) in discriminating metastatic from non-metastatic pelvic lymph nodal sites in endometrial cancer.

Materials and methods

This retrospective study included 40 patients with endometrial cancer who underwent MRI [T2-weighted, dynamic T1-weighted images and diffusion-weighted images with body background suppression (DWIBS), b-values 0 and 1,000?s/mm²], total hysterectomy and pelvic lymphadenectomy. Lymph nodes identifiable on DWIBS were evaluated, classified into six nodal regions, and for each node ADC values, short- and long-axis diameters were measured by two readers. Histopathological findings and follow-up information served as the reference standard.

Results

Average (± standard deviation) mean and minimum ADC region value (0.87?±?0.15 and 0.74?±?0.07?×?10^?3?mm²/s) of metastatic sites (n?=?7) were significantly lower than those of non-metastatic ones (n?=?89; 1.07?±?0.20 and 1.02?±?0.20; p-value?=?0.010 and 0.0004). Mean short-axis and short-to-long axis ratios of metastatic nodes were 7.47?mm and 0.68. Using the minimum ADC region value with threshold 0.807?×?10^?3?mm²/s, sensitivity, specificity, positive and negative predictive value and accuracy were 100?%, 98.3?%, 63.6?%, 100?% and 98.3?%, respectively (reader 1).

Conclusion

In endometrial cancer, mean and minimum ADC region values of metastatic nodal sites are significantly lower than those found at normal sites.

Key Points

? Magnetic resonance imaging is widely used for endometrial cancer. ? Nodes involved with metastases show lower ADC values than normal nodes. ? ADC values show higher diagnostic performances than conventional size criteria. ? Minimum region ADC values perform better than mean region ADC values. ? The radiologist can indicate to the surgeon which nodal stations are involved.     

Diffusion-weighted MR imaging in primary rectal cancer staging demonstrates but does not characterise lymph nodes

Objectives

To evaluate the performance of diffusion-weighted MRI (DWI) for the detection of lymph nodes and for differentiating between benign and metastatic nodes during primary rectal cancer staging.

Methods

Twenty-one patients underwent 1.5-T MRI followed by surgery (± preoperative 5?×?5 Gy). Imaging consisted of T2-weighted MRI, DWI (b0, 500, 1000), and 3DT1-weighted MRI with 1-mm isotropic voxels. The latter was used for accurate detection and per lesion histological validation of nodes. Two independent readers analysed the signal intensity on DWI and measured the mean apparent diffusion coefficient (ADC) for each node (ADC_node) and the ADC of each node relative to the mean tumour ADC (ADC_rel).

Results

DWI detected 6 % more nodes than T2W-MRI. The signal on DWI was not accurate for the differentiation of metastatic nodes (AUC 0.45–0.50). Interobserver reproducibility for the nodal ADC measurements was excellent (ICC 0.93). Mean ADC_node was higher for benign than for malignant nodes (1.15?±?0.24 vs. 1.04?±?0.22 *10^-3 mm²/s), though not statistically significant (P?=?0.10). Area under the ROC curve/sensitivity/specificity for the assessment of metastatic nodes were 0.64/67 %/60 % for ADC_node and 0.67/75 %/61 % for ADC_rel.

Conclusions

DWI can facilitate lymph node detection, but alone it is not reliable for differentiating between benign and malignant lymph nodes.

Key Points

? Diffusion-weighted (DW) magnetic resonance imaging (MRI) offers new information in rectal cancer. ? DW MRI demonstrates more lymph nodes than standard T2-weighted MRI. ? Visual DWI assessment does not discriminate between benign and metastatic nodes. ? Apparent diffusion coefficients do not discriminate between benign and metastatic nodes.     

Accuracy of dual-energy computed tomography for the measurement of iodine concentration using cardiac CT protocols: validation in a phantom model

Purpose

To assess the accuracy of dual-energy CT (DECT) for the quantification of iodine concentrations in a thoracic phantom across various cardiac DECT protocols and simulated patient sizes.

Materials and methods

Experiments were performed on first- and second-generation dual-source CT (DSCT) systems in DECT mode using various cardiac DECT protocols. An anthropomorphic thoracic phantom was equipped with tubular inserts containing known iodine concentrations (0–20 mg/mL) in the cardiac chamber and up to two fat-equivalent rings to simulate different patient sizes. DECT-derived iodine concentrations were measured using dedicated software and compared to true concentrations. General linear regression models were used to identify predictors of measurement accuracy

Results

Correlation between measured and true iodine concentrations (n?=?72) across CT systems and protocols was excellent (R?=?0.994–0.997, P?<?0.0001). Mean measurement errors were 3.0?±?7.0 % and ?2.9?±?3.8 % for first- and second-generation DSCT, respectively. This error increased with simulated patient size. The second-generation DSCT showed the most stable measurements across a wide range of iodine concentrations and simulated patient sizes.

Conclusion

Overall, DECT provides accurate measurements of iodine concentrations across cardiac CT protocols, strengthening the case for DECT-derived blood volume estimates as a surrogate of myocardial blood supply.

Key Points

? Dual-energy CT provides new opportunities for quantitative assessment in cardiac imaging. ? DECT can quantify myocardial iodine as a surrogate for myocardial perfusion. ? DECT measurements of iodine concentrations are overall very accurate. ? The accuracy of such measurements decreases as patient size increases.     

Determination of optimal intravenous contrast agent iodine dose for the detection of liver metastasis at 80-kVp CT

Objectives

To determine the optimal iodine mass (IM) to achieve a 50-HU increase in hepatic attenuation for the detection of liver metastasis based on total body weight (TBW) or body surface area (BSA) at 80-kVp computed tomography (CT) imaging of the liver.

Methods

One-hundred and fifty patients who underwent contrast-enhanced CT at 80-kVp were randomised into three groups: 0.5 gI/kg, 0.4 gI/kg and 0.3 gI/kg. Portal venous phase images were evaluated for hepatic parenchymal enhancement (?HU) and visualisation of liver metastasis. Iodine mass per BSA (gI/m²) calculated in individual patients were evaluated.

Results

Mean ?HU for the 0.5 gI/kg group (84.2 HU) was higher than in the 0.4 gI/kg (66.1 HU) and 0.3 gI/kg (53.7 HU) groups (P?<?0.001). Linear correlation equations between ?HU and IM per TBW or BSA are ?HU?=?7.0?+?153.0?×?IM/TBW (r?=?0.73, P?<?0.001) and ?HU?=?11.4?+?4.0?×?IM/BSA (r?=?0.75, P?<?0.001), respectively. The three groups were comparable for the visualisation of hepatic metastases.

Conclusions

The iodine mass to achieve a 50-HU increase in hepatic attenuation at 80-kVp CT was estimated to be 0.28 gI/kg of body weight or 9.6 gI/m² of body surface area.

Key Points

? Hepatic enhancement is expressed as ?HU?=?7.0?+?153.0?×?IM [g]/TBW [kg]. ? Hepatic enhancement is expressed as ?HU?=?11.4?+?4.0?×?IM [g]/BSA [m ² ]. ? Essential iodine dose at 80-kVp CT was 0.28 gI/kg or 9.6 gI/m ² .     

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.     

Hepatocellular carcinoma and focal nodular hyperplasia of the liver: differentiation with CT spectral imaging

Objectives

To investigate the value of CT spectral imaging in differentiating hepatocellular carcinoma (HCC) from focal nodular hyperplasia (FNH) during the arterial phase (AP) and portal venous phase (PP).

Methods

Fifty-eight patients with 42 HCCs and 16 FNHs underwent spectral CT during AP and PP. The lesion–liver contrast-to-noise ratio (CNR) at different energy levels, normalised iodine concentrations (NIC) and the lesion–normal parenchyma iodine concentration ratio (LNR) were calculated. The two-sample t test compared quantitative parameters. Two readers qualitatively assessed lesion types according to imaging features. Sensitivity and specificity of the qualitative and quantitative studies were compared.

Results

In general, CNRs at low energy levels (40–70 keV) were higher than those at high energy levels (80–140 keV). NICs and LNRs for HCC differed significantly from those of FNH: mean NICs were 0.25 mg/mL?±?0.08 versus 0.42 mg/mL?±?0.12 in AP and 0.52 mg/mL?±?0.14 versus 0.86 mg/mL?±?0.18 in PP. Mean LNRs were 2.97?±?0.50 versus 6.15?±?0.62 in AP and 0.99?±?0.12 versus 1.22?±?0.26 in PP. NICs and LNRs for HCC were lower than those of FNH. LNR in AP had the highest sensitivity and specificity in differentiating HCC from FNH.

Conclusions

CT spectral imaging may help to increase detectability of lesions and accuracy of differentiating HCC from FNH.

Key Points

? CT spectral imaging may help to detect hepatocellular carcinoma (HCC). ? CT spectral imaging may help differentiate HCC from focal nodular hyperplasia. ? Quantitative analysis of iodine concentration provides greater diagnostic confidence. ? Treatment can be given with greater confidence.     

Body size indices to determine iodine mass with contrast-enhanced multi-detector computed tomography of the upper abdomen: does body surface area outperform total body weight or lean body weight?

Objective

To compare total body weight (TBW), lean body weight (LBW) and body surface area (BSA) for the adjustment of the iodine dose required for contrast-enhanced multi-detector computed tomography (MDCT) of the aorta and the liver.

Methods

One hundred and three patients undergoing MDCT of the abdomen were randomised into three groups: the TBW group receiving 0.6 g iodine/kg of TBW (n?=?33), the LBW group receiving 0.75 g iodine/kg of LBW (n?=?35) and the BSA group receiving 22 g iodine/m² (n?=?35). ?HU (increases in CT value) per gram of iodine (?HU/g) and adjusted maximum hepatic enhancement (adjusted MHE; ?HU/[g iodine/kg]) correlated with three groups using linear regressions.

Results

Correlation coefficients of ?HU/g were 0.67 (TBW), 0.86 (LBW) and 0.85 (BSA) for the aorta, and 0.74 (TBW), 0.77 (LBW) and 0.84 (BSA) for the liver. Adjusted MHE was constant at 70.2 with LBW and at 2.69 with BSA, but correlated positively with TBW (r?=?0.58, P?<?0.001).

Conclusion

Iodine load may need to be tailored by LBW or BSA in contrast enhanced MDCT of the abdomen. BSA is a simple and feasible index for the determination of iodine dose in individual patients.

Key Points

? Optimisation of enhancement is very important for high quality MDCT. ? Iodine dose is best adjusted according to LBW or BSA. ? BSA may be adopted because calculation is simple. ? Iodine dose of 0.712 g/kg LBW/18.6 g/m ² BSA gives 50 HU hepatic enhancement.     

Quality control within the multicentre perfusion CT study of primary colorectal cancer (PROSPeCT): results of an iodine density phantom study

Objectives

To assess the cross-centre consistency of iodine enhancement, contrast-to-noise ratio and radiation dose in a multicentre perfusion CT trial of colorectal cancer.

Materials and methods

A cylindrical water phantom containing different iodine inserts was examined on seven CT models in 13 hospitals. The relationship between CT number (Hounsfield units, HU) and iodine concentration (milligrams per millilitre) was established and contrast-to-noise ratios (CNRs) calculated. Radiation doses (CTDI_vol, DLP) were compared across all sites.

Results

There was a linear relationship between CT number and iodine density. Iodine enhancement varied by a factor of at most 1.10, and image noise by at most 1.5 across the study sites. At an iodine concentration of 1 mg ml^?1 and 100 kV, CNRs ranged from 3.6 to 4.8 in the 220-mm phantom and from 1.4 to 1.9 in the 300-mm phantom. Doses varied by a factor of at most 2.4, but remained within study dose constraints. Iterative reconstruction algorithms did not alter iodine enhancement but resulted in reduced image noise by a factor of at most 2.2, allowing a potential dose decrease of at most 80 % compared to filtered back projection (FBP).

Conclusions

Quality control of CT performance across centres indicates that CNR values remain relatively consistent across all sites, giving acceptable image quality within the agreed dose constraints.

Key Points

? Quality control is essential in a multicentre setting to enable CT quantification. ? CNRs in a body-sized phantom had the recommended value of at least 1.5. ? CTDIs and DLPs varied by factors of 1.8 and 2.4 respectively.     

Radio(chemo)therapy in the management of squamous cell carcinoma of cervical lymph nodes from an unknown primary site

Purpose

The goal was to retrospectively review the outcome of patients with cervical lymph node metastases of squamuos cell carcinoma of unknown primary site (CUP) treated with radio(chemo)therapy.

Patients and methods

A total of 65?patients with CUP N1?C3, M0, treated between 1988 and 2009 were evaluated: 61?patients underwent surgical resection followed by postoperative radio(chemo)therapy, 4?patients received definitive radiochemotherapy. Radiotherapy of bilateral neck nodes?+?the parapharyngeal region (COMP-RT) was performed in 48?patients (80%) and a unilateral radiotherapy of lymph nodes (UL-RT) in 17?patients (20%).

Results

After a median follow-up time of 64?months (range 3?C219?months), the estimated 2- and 5-year overall survival (OS) rates were 71?±?6% and 48?±?7%, respectively. The recurrent free survival (RFS) rate at 2- and 5-years was 58?±?6% and 48%?±?7%, respectively. Extracapsular spread, resection status (R0 vs. R1/R2), neck lymph node level (I?CIII vs. IV?CV), and Karnofsky index (60?C70 vs. 80?C100) were significant prognostic factors for OS and RFS in the univariate analysis. Lower nodal stage (N1/N2a vs. N2b/N2c/N3) was significantly associated with a better OS. Resection status and involvement of lymph node level IV significantly affected the OS and RFS in the multivariate analysis. COMP-RT or concurrent chemotherapy was not associated with a better OS or RFS.

Conclusion

An advantage of comprehensive radiotherapy or radiochemotherapy compared with unilateral radiotherapy of lymph nodes was not observed.     

Distinguishing enhancing from nonenhancing renal masses with dual-source dual-energy CT: iodine quantification versus standard enhancement measurements

Purpose

To compare the diagnostic accuracy of iodine quantification and standard enhancement measurements in distinguishing enhancing from nonenhancing renal masses.

Materials and methods

The Institutional Review Board approved this retrospective study conducted from data found in institutional patient databases and archives. Seventy-two renal masses were characterised as enhancing or nonenhancing using standard enhancement measurements (in HU) and iodine quantification (in mg/ml). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of standard enhancement measurements and iodine quantification were calculated from χ ² tests of contingency with histopathology or imaging follow-up as the reference standard. Difference in accuracy was assessed by means of McNemar analysis.

Results

Sensitivity, specificity, PPV, NPV and diagnostic accuracy for standard enhancement measurements and iodine quantification were 77.7 %, 100 %, 100 %, 81.8 %, 89 % and 100 %, 94.4 %, 94.7, 100 % and 97 %, respectively. The McNemar analysis showed that the accuracy of iodine quantification was significantly better (P?<?0.001) than that of standard enhancement measurements.

Conclusion

Compared with standard enhancement measurements, whole-tumour iodine quantification is more accurate in distinguishing enhancing from nonenhancing renal masses.

Key Points

? Enhancement of renal lesions is important when differentiating benign from malignant tumours. ? Dual-energy CT offers measurement of iodine uptake rather than mere enhancement values. ? Whole-tumour iodine quantification seems more accurate than standard CT enhancement measurements.     

Perfusion and diffusion characteristics of cervical cancer based on intraxovel incoherent motion MR imaging-a pilot study

Objectives

To investigate the tissue characteristics of cervical cancer based on the intravoxel incoherent motion (IVIM) model and to assess the IVIM parameters in tissue differentiation in the female pelvis.

Methods

Sixteen treatment-naïve cervical cancer and 17 age-matched healthy subjects were prospectively recruited for diffusion-weighted (b?=?0–1,000 s/mm²) and standard pelvic MRI. Bi-exponential analysis was performed to derive the perfusion parameters f (perfusion fraction) and D* (pseudodiffusion coefficient) as well as the diffusion parameter D (true molecular diffusion coefficient) in cervical cancer (n?=?16), normal cervix (n?=?17), myometrium (n?=?33) and leiomyoma (n?=?14). Apparent diffusion coefficient (ADC) was calculated. Kruskal–Wallis test and receiver operating characteristics (ROC) curves were used.

Results

Cervical cancer had the lowest f (14.9?±?2.6 %) and was significantly different from normal cervix and leiomyoma (p?<?0.05). The D (0.86?±?0.16 x 10^-3 mm2/s) was lowest in cervical cancer and was significantly different from normal cervix and myometrium (p?<?0.05) but not leiomyoma. No difference was observed in D*. D was consistently lower than ADC in all tissues. ROC curves indicated that f < 16.38 %, D < 1.04?×?10^-3 mm²/s and ADC < 1.13?×?10^-3 mm²/s could differentiate cervical cancer from non-malignant tissues (AUC 0.773–0.908).

Conclusions

Cervical cancer has low perfusion and diffusion IVIM characteristics with promising potential for tissue differentiation.

Key Points

? Diffusion-weighted MRI is increasingly applied in evaluation of cervical cancer. ? Cervical cancer has distinctive perfusion and diffusion characteristics. ? Intravoxel incoherent motion characteristics can differentiate cervical cancer from non-malignant uterine tissues.     

1H-Magnetic Resonance Spectroscopy in diffuse and focal cervical cord lesions in Multiple Sclerosis

Objectives

To investigate differences between focal and diffuse cervical lesions in multiple sclerosis (MS) by proton magnetic resonance spectroscopy (¹H-MRS) at 1.5 T in comparison to quantitative MR imaging of the upper cervical cord area and T2 relaxometry at baseline and follow-up.

Methods

Including 22 MS patients with persistent spinal cord symptoms by either diffuse or focal lesions and 17 controls, we acquired MRS, the mean cord area and the water T2 relaxation time and disability at baseline and follow-up. Cross-sectional analyses included group-level comparisons and correlation studies. Follow-up studies covered assessment of reproducibility and progression of the baseline results.

Results

Compared with focal lesions, diffuse lesions were attended by more cord atrophy, longer T2, elevated levels of creatine (Cre) and reduced N-acetyl aspartate (NAA)/Cre (focal/diffuse: 83?±?9/73?±?15 mm², 121?±?21/104?±?13 ms, 3.6?±?1.1/5.1?±?2.4 mM, 2.4?±?1.1/2.0?±?0.9). NAA/Cre at baseline was associated significantly with cord atrophy and with clinical progression during follow-up. Baseline MRS results were not significantly correlated to the clinical disability parameters. The reproducibility of MRS was 0.17-0.30. Longitudinal changes of the MRS results were not statistically significant.

Conclusions

MRS indicated differences in demyelination and gliosis between diffuse and focal cervical lesions in MS. Although longitudinal spectral and clinical changes were sparse, NAA/Cre turned out to be the most sensitive spectral parameter.

Key Points

? MR spectroscopy shows differences between focal and diffuse spinal cord MS lesions. ? MRS indicates axonal degeneration and gliosis in MS compared with controls. ? MRS results are associated with cervical cord atrophy. ? MRS may help clinicians to monitor spinal cord damage in MS.     

Quantitative evaluation of MR perfusion imaging using blood pool contrast agent in subjects without pulmonary diseases and in patients with pulmonary embolism

Objective

To assess the feasibility of time-resolved parallel three-dimensional magnetic resonance imaging (MRI) for quantitative analysis of pulmonary perfusion using a blood pool contrast agent.

Methods

Quantitative perfusion analysis was performed using novel software to assess pulmonary blood flow (PBF), pulmonary blood volume (PBV) and mean transit time (MTT) in a quantitative manner.

Results

The evaluation of lung perfusion in the normal subjects showed an increase of PBF, PBV ventrally to dorsally (gravitational direction), and the highest values at the upper lobe, with a decrease to the middle and lower lobe (isogravitational direction). MTT showed no relevant changes in either the gravitational or isogravitational directions. In comparison with normally perfused lung areas (in diseased patients), the pulmonary embolism (PE) regions showed a significantly lower mean PBF (20?±?0.6?ml/100?ml/min, normal region 94?±?1?ml/100?ml/min; P?P?P?Conclusion Our results demonstrate the feasibility of using time-resolved dynamic contrast-enhanced MRI to determine normal range and regional variation of pulmonary perfusion and perfusion deficits in patients with PE.

Key Points

? Recently introduced blood pool contrast agents improve MR evaluation of lung perfusion ? Regional differences in lung perfusion indicating a gravitational and isogravitational dependency. ? Focal areas of significantly decreased perfusion are detectable in pulmonary embolism.     

Assessment of therapeutic response in ankylosing spondylitis patients undergoing anti-tumour necrosis factor therapy by whole-body magnetic resonance imaging

Objectives

Multifocal musculoskeletal inflammation is common in ankylosing spondylitis (AS) and is effectively treated by expensive anti-TNF (tumour necrosis factor) therapy. This study evaluated assessment of response by whole-body (WB) MRI compared with clinical assessment in AS patients during etanercept therapy.

Methods

Ten patients with AS underwent a 12-month therapy with etanercept. Clinical markers were monitored [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP)] and patients underwent WBMRI (1.5 T, STIR and T1-weighted) at three different time points (0, 26 and 52 weeks). WBMRI was evaluated and correlated with clinical scores.

Results

The BASDAI index decreased under therapy from 5.5?±?0.5 (week 0) to 1.7?±?0.5 (week 52, P?<?0.05). CRP declined from 15.7?±?2.2 mg/dl (week 0) to 0.9?±?0.9 mg/dl (week 52, P?<?0.05). In WBMRI, the sum of all lesions showed a significant decrease from week 0 (38.9?±?3.4) to week 52 (2.2?±?0.9, 94.3 % reduction). WBMRI detected more areas of synovitis and enthesitis than clinical examination alone.

Conclusions

AS activity significantly decreased under etanercept therapy, which was proven by clinical examination and WBMRI. WBMRI detected more inflammatory lesions than clinical examination alone. The results suggest that WBMRI improves the detection of inflammatory changes and the assessment of their course under therapy.

Key Points

? Multifocal musculoskeletal inflammation in AS is effectively treated by anti-TNF therapy. ? Inflammatory lesions can be assessed by clinical examination and whole-body MRI. ? AS activity significantly decreased under therapy as shown by WBMRI/clinical examination. ? WBMRI detected more inflammatory lesions than clinical examination alone. ? WBMRI improves detection of inflammatory changes and may help evaluation of therapy.     

Treatment outcomes of patients with cervical cancer with complete metabolic responses after definitive chemoradiotherapy

Purpose

We sought to evaluate failure patterns and prognostic factors predictive of recurrences and survival in cervical cancer patients who are treated with definitive chemoradiotherapy (ChRT), who have a subsequent complete metabolic response (CMR) with ¹⁸?F-fluorodeoxyglucose positron-emission tomography (FDG-PET) after treatment.

Methods

The records of 152 cervical cancer patients who were treated with definitive chemoradiotherapy were evaluated. All patients underwent pre-treatment positron emission tomography (PET-CT), and post-treatment PET-CT was performed within a median of 3.9 months (range, 3.0–9.8 months) after the completion of ChRT. The prognoses of partial response/progressive disease (PR/PD) cases (30 patients, 18 %) and CMR cases (122 patients, %82) were evaluated. Univariate and multivariate analysis effecting the treatment outcome was performed in CMR cases.

Results

The median follow-ups for all patients and surviving patients were 28.7 (range, 3.3–78.7 months) and 33.2 months (range, 6.23–78.7 months), respectively. Four-year overall survival (OS) rate was significantly better in patients with CMR compared to patients with PR/PD (66.9 % vs. 12.4 %, p?<?0.001, respectively). Patients with PR/PD had higher maximum standardized uptake value (SUV_max) of primary cervical tumor (26.4?±?10.1 vs. 15.9?±?6.3; p?<?0.001) and larger tumor (6.4 cm?±?2.3 cm vs. 5.0 cm?±?1.4 cm; p?<?0.001) compared to patients with CMR. Of the 122 patients with post-treatment CMRs, 25 (21 %) developed local, locoregional, or distant failure. In univariate analysis, tumor size ≥ 5 cm, ‘International Federation of Obstetricians and Gynecologists’ (FIGO) stage?≥?IIB, and pelvic and/or para-aortic lymph node metastasis were predictive of both overall survival (OS) and disease-free survival (DFS), while histology was predictive of only OS. In multivariate analysis, tumor size, stage and lymph node metastasis were predictive of OS and DFS.

Conclusion

Although CMR is associated with better outcomes, relapses remain problematic, especially in patients with bulky tumors (≥ 5 cm), extensive stage (≥ IIB) or pelvic and/or para-aortic lymph node metastasis. These findings could support the need for more aggressive treatment or adjuvant chemotherapy regimens.     

Detection of underlying malignancy in patients with paraneoplastic neurological syndromes: comparison of 18F-FDG PET/CT and contrast-enhanced CT

Purpose

To determine the value of combined ¹⁸F-FDG PET/CT with diagnostic contrast-enhanced CT (CECT) in detecting primary malignancies and metastases in patients with paraneoplastic neurological syndromes (PNS) and to compare this with CECT alone.

Methods

PET/CT scans from 66 patients with PNS were retrospectively evaluated. Two blinded readers initially reviewed the CECT portion of each PET/CT scan. In a second session 3 months later, the readers analysed the combined PET/CT scans. Findings on each study were assessed using a four-point-scale (1 normal/benign; 2 inconclusive, further diagnostic work-up may be necessary; 3 malignant; 4 inflammatory). Sensitivity and specificity for malignant findings were calculated for PET/CT and CECT. Interreader agreement was determined by calculating Cohen’s kappa. Pooled data from clinical follow-up (including histopathology and follow-up imaging, median follow-up 20.0 months) served as the reference gold standard.

Results

Both readers classified 12 findings in ten patients (15 %) as malignant on the PET/CT scans (two patients had two primary tumours). One such imaging finding (suspected thymic cancer) was false-positive (i.e. benign histology). The most common tumours were bronchial carcinoma (n?=?3), lymph node metastases of gynaecological tumours (n?=?3) and tonsillar carcinoma (n?=?2). Three of 12 findings (25 %) were not detected by CECT alone (cervical carcinoma, lymph node metastasis and tonsillar carcinoma). In a per-patient analysis, sensitivity and specificity for malignant findings were 100 % and 90 % for PET/CT and 78 % and 88 % for CECT. In 24 % (reader 1) and 21 % (reader 2) of the patients, the PET/CT findings were inconclusive. Of these findings, 57 % (reader 1) and 56 % (reader 2) were only diagnosed with PET (e.g. focal FDG uptake of the thyroid, gastrointestinal tract and ovaries). On follow-up, none of these findings corresponded to malignancy. Overall agreement between the two readers was excellent with a Cohen’s kappa of 0.95?±?0.04 (p?<?0.001) for PET/CT and 0.97?±?0.03 (p?<?0.001) for CECT alone.

Conclusion

In this cohort of patients with PNS, PET/CT exhibited improved detection of underlying malignancy versus CECT alone. While hybrid imaging produces a greater number of inconclusive findings, sensitivity is increased for the detection of head and neck and gynaecological malignancies as well as metastatic lymph node involvement.     

Dose reduction in dynamic CT stress myocardial perfusion imaging: comparison of 80-kV/370-mAs and 100-kV/300-mAs protocols

Objectives

To determine the effect of reduced 80-kV tube voltage with increased 370-mAs tube current on radiation dose, image quality and estimated myocardial blood flow (MBF) of dynamic CT stress myocardial perfusion imaging (CTP) in patients with a normal body mass index (BMI) compared with a 100-kV and 300-mAs protocol.

Methods

Thirty patients with a normal BMI (<25 kg/m²) with known or suspected coronary artery disease underwent adenosine-stress dual-source dynamic CTP. Patients were randomised to 80-kV/370-mAs (n?=?15) or 100-kV/300-mAs (n?=?15) imaging. Maximal enhancement and noise of the left ventricular (LV) cavity, contrast-to-noise ratio (CNR) and MBF of the two groups were compared.

Results

Imaging with 80-kV/370-mAs instead of 100-kV/300-mAs was associated with 40 % lower radiation dose (mean dose–length product, 359?±?66 vs 628?±?112 mGy?cm; P?<?0.001 ) with no significant difference in CNR (34.5?±?13.4 vs 33.5?±?10.4; P?=?0.81) or MBF in non-ischaemic myocardium (0.95?±?0.20 vs 0.99?±?0.25 ml/min/g; P?=?0.66). Studies obtained using 80-kV/370-mAs were associated with 30.9 % higher maximal enhancement (804?±?204 vs 614?±?115 HU; P?<?0.005), and 31.2 % greater noise (22.7?±?3.5 vs 17.4?±?2.6; P?<?0.001).

Conclusions

Dynamic CTP using 80-kV/370-mA instead of 100-kV/300-mAs allowed 40 % dose reduction without compromising image quality or MBF. Tube voltage of 80-kV should be considered for individuals with a normal BMI.

Key Points

? CT stress perfusion imaging (CTP) is increasingly used to assess myocardial function. ? Dynamic CTP is feasible at 80-kV in patients with normal BMI. ? An 80-kV/370-mAs protocol allows 40 % dose reduction compared with 100-kV/300-mAs. ? Contrast-to-noise ratio and myocardial blood flow of the two protocols were comparable.