Comparison of FDG-PET, MRI and CT for post radiofrequency ablation evaluation of hepatic tumors

Purpose

Treatment effect of radiofrequency ablation (RFA) is traditionally accomplished with MRI and/or CT. The aim of the study was to assess the role of FDG-PET in post RFA hepatic tumor evaluation, in comparison with MRI and CT.

Materials and methods

28 patients (33 hepatic RFA lesions) who had post RFA FDG-PET within 8 weeks of abdominopelvic MRI or CT were retrospectively reviewed. Accuracy of FDG-PET on post hepatic RFA evaluation was compared with MRI and/or CT based on clinical and imaging follow-up.

Results

Among total of 33 RFA-treated lesions, 17 had residual or recurrent tumor (positive). PET identified 16 with a sensitivity of 94.1 %. Of these 17 lesions, 12 had concurrent MRI and 8 were positive with a sensitivity of 66.7 %. Similarly, 6 out of the 17 lesions had CT and 4 were positive with a sensitivity of 66.7 %. Sixteen lesions were successfully ablated (negative). Among them FDG-PET was negative in 13 with a specificity of 81.3 %; MRI was performed in 8 and 7 were negative with a specificity of 87.5 %; CT was performed in 8 and 5 were negative with a specificity of 62.5 %. The overall accuracy of PET, MRI and CT was 87.9, 75.0, and 64.3 %, respectively. The average scan numbers for PET, MRI and CT to achieve a final accurate diagnosis were 1.121, 1.316 and 1.250, with a corresponding cost of $1455.2, $1845.8, and $933.8, respectively.

Conclusions

The study suggests that FDG-PET is superior to MRI and/or CT and is more cost-effective in post RFA hepatic tumor assessment.     

Temporal lobe epilepsy due to meningoencephaloceles into the greater sphenoid wing: a consequence of idiopathic intracranial hypertension?

Purpose

Antero-inferior temporal lobe meningoencephaloceles are a rare, but increasingly recognized cause of drug-resistant temporal lobe epilepsy (TLE). In order to evaluate whether these lesions are related to idiopathic intracranial hypertension (IIH), we analyzed clinical and MRI findings of a cohort of patients undergoing presurgical work-up.

Methods

Seizure onset in the anterior temporal lobe was proven by EEG electrodes in 22 patients, and in 21 patients, anterior temporal lobectomy (mostly with sparing of the hippocampus) was performed. MRI signs of IIH (in particular empty sella) and the volumes of the ventricles and external CSF spaces were determined and related to the body mass index (BMI) and clinical outcome.

Results

Six of seven obese (BMI > 30 kg/m²) compared to four of 15 non-obese patients had partial empty or empty sella (p = 0.007). Bilateral lesions were found in all obese and 11 patients. Seizure freedom (Engel class 1A) was achieved in 12 of 21 patients (5 obese compared to 7 non-obese patients). BMI was related to the volume of the external CSF spaces (r = 0.467), and age at seizure onset was higher in obese patients.

Conclusion

Roughly a third of patients with temporal lobe epilepsy due to antero-inferior meningoencephaloceles is obese and has MRI signs of idiopathic intracranial hypertension.

     

MRI displays involvement of the temporalis muscle and the deep temporal artery in patients with giant cell arteritis

Purpose

To assess deep temporal artery and temporalis muscle involvement in patients with giant cell arteritis (GCA).

Material and methods

Ninety-nine patients who received magnetic resonance imaging (MRI) and superficial temporal artery biopsy (TAB) were included in this study. Patients with positive TAB (n?=?61) were defined as GCA patients, those with negative TAB (n?=?38) as the GCA-negative reference group. Contrast-enhanced T1w-images were acquired utilizing 1.5 T and 3 T MRI. Two radiologists assessed the images. Mural contrast-hyperenhancement and wall thickening of the deep temporal artery and hyperenhancement of the muscle were defined as inflammation. MRI results were correlated with jaw claudication in 70 patients.

Results

The two observers found temporalis muscle involvement in 19.7 % (n?=?12) and 21.3 % (n?=?13) of GCA patients. It occurred bilaterally in 100 %. Specificities were 92/97 % and sensitivities were 20/21 %. Deep temporal artery involvement was found in 34.4 % (n?=?21) and 49.2 % (n?=?30) and occurred bilaterally in 80/90.5 %. Specificities were 84/95 % and sensitivities were 34/49 %. Both structures were affected simultaneously in 18/21.3 %. Jaw claudication correlated moderately with inflammation of the temporalis muscle (r?=?0.31; p?Conclusion MRI visualizes changes in the temporalis muscle and the deep temporal artery in GCA. Moderate correlation of clinical symptoms with MRI results was observed.

Key Points

? Approximately 20 % of GCA patients presented with temporalis muscle inflammation. ? A total of 34-49 % of GCA patients presented with vasculitis of the deep temporal artery. ? In approximately 20 % of GCA patients, both structures were simultaneously involved. ? Involvement of both structures correlated moderately with presence of jaw claudication. ? MRI is a suitable tool for the assessment of vasculitis and muscle inflammation.     

Whole-body MRI for the detection of bone marrow involvement in lymphoma: prospective study in 116 patients and comparison with FDG-PET

Objective

To assess and compare the value of whole-body MRI with FDG-PET for detecting bone marrow involvement in lymphoma.

Methods

A total of 116 patients with newly diagnosed lymphoma prospectively underwent whole-body MRI and blind bone marrow biopsy (BMB) of the posterior iliac crest. Of 116 patients, 80 also underwent FDG-PET. Patient-based sensitivities of whole-body MRI for detecting bone marrow involvement were calculated using BMB as reference standard and compared with FDG-PET in aggressive and indolent lymphomas separately.

Results

Sensitivity of whole-body MRI in all lymphomas was 45.5 % [95 % confidence interval (CI): 29.8–62.0 %]. Sensitivity of whole-body MRI in aggressive lymphoma [88.9 % (95 % CI: 54.3–100 %)] was significantly higher (P?=?0.0029) than that in indolent lymphoma [23.5 % (95 % CI: 9.1–47.8 %)]. Sensitivity of FDG-PET in aggressive lymphoma [83.3 % (95 % CI: 41.8–98.9 %)] was also significantly higher (P?=?0.026) than that in indolent lymphoma [12.5 % (95 % CI: 0–49.2 %)]. There were no significant differences in sensitivity between whole-body MRI and FDG-PET (P?=?1.00)

Conclusion

Sensitivity of whole-body MRI for detecting lymphomatous bone marrow involvement is too low to (partially) replace BMB. Sensitivity of whole-body MRI is significantly higher in aggressive lymphoma than in indolent lymphoma and is equal to FDG-PET in both entities.

Key Points

? Bone marrow involvement in lymphoma has prognostic and therapeutic implications. ? Blind bone marrow biopsy (BMB) is standard for bone marrow assessment. ? Neither whole-body MRI nor FDG-PET can yet replace BMB. ? Both techniques have higher sensitivity in aggressive than in indolent lymphoma. ? Both imaging techniques are complementary to BMB.     

The usefulness of 18F-FDG PET/MRI fusion image in diagnosing pancreatic tumor: comparison with 18F-FDG PET/CT

Purpose

This study aimed at demonstrating the feasibility of retrospectively fused ¹⁸F FDG-PET and MRI (PET/MRI fusion image) in diagnosing pancreatic tumor, in particular differentiating malignant tumor from benign lesions. In addition, we evaluated additional findings characterizing pancreatic lesions by FDG-PET/MRI fusion image.

Methods

We analyzed retrospectively 119 patients: 96 cancers and 23 benign lesions. FDG-PET/MRI fusion images (PET/T1 WI or PET/T2WI) were made by dedicated software using 1.5 Tesla (T) MRI image and FDG-PET images. These images were interpreted by two well-trained radiologists without knowledge of clinical information and compared with FDG-PET/CT images. We compared the differential diagnostic capability between PET/CT and FDG-PET/MRI fusion image. In addition, we evaluated additional findings such as tumor structure and tumor invasion.

Results

FDG-PET/MRI fusion image significantly improved accuracy compared with that of PET/CT (96.6 vs. 86.6 %). As additional finding, dilatation of main pancreatic duct was noted in 65.9 % of solid types and in 22.6 % of cystic types, on PET/MRI-T2 fusion image. Similarly, encasement of adjacent vessels was noted in 43.1 % of solid types and in 6.5 % of cystic types. Particularly in cystic types, intra-tumor structures such as mural nodule (35.4 %) or intra-cystic septum (74.2 %) were detected additionally. Besides, PET/MRI-T2 fusion image could detect extra benign cystic lesions (9.1 % in solid type and 9.7 % in cystic type) that were not noted by PET/CT.

Conclusions

In diagnosing pancreatic lesions, FDG-PET/MRI fusion image was useful in differentiating pancreatic cancer from benign lesions. Furthermore, it was helpful in evaluating relationship between lesions and surrounding tissues as well as in detecting extra benign cysts.     

MRI findings in glutamic acid decarboxylase associated autoimmune epilepsy

Purpose

Glutamic acid decarboxylase (GAD65) has been implicated in a number of autoimmune-associated neurologic syndromes, including autoimmune epilepsy. This study categorizes the spectrum of MRI findings in patients with a clinical diagnosis of autoimmune epilepsy and elevated serum GAD65 autoantibodies.

Methods

An institutional database search identified patients with elevated serum GAD65 antibodies and a clinical diagnosis of autoimmune epilepsy who had undergone brain MRI. Imaging studies were reviewed by three board-certified neuroradiologists and one neuroradiology fellow. Studies were evaluated for cortical/subcortical and hippocampal signal abnormality, cerebellar and cerebral volume loss, mesial temporal sclerosis, and parenchymal/leptomeningeal enhancement. The electronic medical record was reviewed for relevant clinical information and laboratory markers.

Results

A study cohort of 19 patients was identified. The majority of patients were female (84%), with a mean age of onset of 27 years. Serum GAD65 titers ranged from 33 to 4415 nmol/L (normal <?0.02 nmol/L). The most common presentation was medically intractable, complex partial seizures with temporal lobe onset. Parenchymal atrophy was the most common imaging finding (47%), with a subset of patients demonstrating cortical/subcortical parenchymal T2 hyperintensity (37%) or abnormal hippocampal signal (26%). No patients demonstrated abnormal parenchymal/leptomeningeal enhancement.

Conclusion

The most common MRI finding in GAD65-associated autoimmune epilepsy is disproportionate parenchymal atrophy for age, often associated with abnormal cortical/subcortical T2 hyperintensities. Hippocampal abnormalities are seen in a minority of patients. This constellation of findings in a patient with medically intractable epilepsy should raise the possibility of GAD65 autoimmunity.

     

Temporal epilepsy lesions may be detected by the voxel-based quantitative analysis of brain FDG-PET images using an original block-matching normalization software

Introduction

Statistical parametric mapping (SPM) provides useful voxel-by-voxel analyses of brain images from ¹⁸F-fluorodesoxyglucose positron emission tomography (FDG-PET) after an initial step of spatial normalization through an anatomical template model. In the setting of the preoperative workup of patients with temporal epilepsy, this study aimed at assessing a block-matching (BM) normalization method, where most transformations are computed through small blocks, a principle that minimizes artefacts and overcomes additional image-filtering.

Methods

Brain FDG-PET images from 31 patients with well-characterised temporal lobe epilepsy and among whom 22 had common mesial temporal lobe epilepsy were retrospectively analysed using both BM and conventional SPM normalization methods and with PET images from age-adjusted controls. Different threshold p values corrected for cluster volume were considered (0.01, 0.005, and 0.001).

Results

The use of BM provided equivalent values to those of SPM with regard to the overall volumes of temporal and extra-temporal hypometabolism, as well as similar sensitivity for detecting the involved temporal lobe, reaching 87 and 94 % for SPM and BM, respectively, at a threshold p value of 0.01. However, the ability to more accurately localize brain lesions within the mesial portion of the temporal lobe was a little higher with BM than with SPM with respective sensitivities reaching 78 % for BM and 45 % for SPM (p < 0.05).

Conclusions

BM normalization compares well with conventional SPM for the voxel-based quantitative analysis of the FDG-PET images from temporal epilepsy patients. Further studies in different population are needed to determine whether BM is truly an accurate alternative to SPM in this setting.

     

Usefulness of extent analysis for statistical parametric mapping with asymmetry index using inter-ictal FGD-PET in mesial temporal lobe epilepsy

Objective

Inter-ictal ¹⁸F-2-fluoro-deoxy-d-glucose-positron emission tomography (FDG-PET) is widely used for preoperative evaluation to identify epileptogenic zones in patients with temporal lobe epilepsy. In this study, we combined statistical parametric mapping (SPM) with the asymmetry index and volume-of-interest (VOI) based extent analysis employing preoperative FDG-PET in unilateral mesial temporal lobe epilepsy (MTLE) patients. We also evaluated the detection utility of these techniques for automated identification of abnormalities in the unilateral hippocampal area later confirmed to be epileptogenic zones by surgical treatment and subsequent good seizure control.

Methods

FDG-PET scans of 17 patients (9 males, mean age 35?years, age range 16?C60?years) were retrospectively analyzed. All patients had been preoperatively diagnosed with unilateral MTLE. The surgical outcomes of all patients were Engel class 1A or 1B with postoperative follow-up of 2?years. FDG-PET images were spatially normalized and smoothed. After two voxel-value adjustments, one employing the asymmetry index and the other global normalization, had been applied to the images separately, voxel-based statistical comparisons were performed with 20 controls. Peak analysis and extent analysis in the VOI in the parahippocampal gyrus were conducted for SPM. For the extent analysis, a receiver operating characteristic (ROC) curve was devised to calculate the area under the curve and to determine the optimal threshold of extent.

Results

The accuracy of the method employing the asymmetry index was better than that of the global normalization method for both the peak and the extent analysis. The ROC analysis results, for the extent analysis, yielded an area under the curve of 0.971, such that the accuracy and optimal extent threshold of judgment were 92 and 32.9%, respectively.

Conclusion

Statistical z-score mapping with the asymmetry index was more sensitive for detecting regional glucose hypometabolism and more accurate for identifying the side harboring the epileptogenic zone using inter-ictal FDG-PET in unilateral MTLE than z-score mapping with global normalization. Moreover, the automated determination of the side with the epileptogenic zone in unilateral MTLE showed improved accuracy when the combination of SPM with the asymmetry index and extent analysis was applied based on the VOI in the parahippocampal gyrus.     

Whole-body MRI with diffusion-weighted sequence for staging of patients with suspected ovarian cancer: a clinical feasibility study in comparison to CT and FDG-PET/CT

Objectives

To evaluate whole-body MRI with diffusion-weighted sequence (WB-DWI/MRI) for staging and assessing operability compared with CT and FDG-PET/CT in patients with suspected ovarian cancer.

Methods

Thirty-two patients underwent 3-T WB-DWI/MRI, ¹⁸?F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and CT before diagnostic open laparoscopy (DOL). Imaging findings for tumour characterisation, peritoneal and retroperitoneal staging were correlated with histopathology after DOL and/or open surgery. For distant metastases, FDG-PET/CT or image-guided biopsies were the reference standards. For tumour characterisation and peritoneal staging, WB-DWI/MRI was compared with CT and FDG-PET/CT. Interobserver agreement for WB-DWI/MRI was determined.

Results

WB-DWI/MRI showed 94 % accuracy for primary tumour characterisation compared with 88 % for CT and 94 % for FDG-PET/CT. WB-DWI/MRI showed higher accuracy of 91 % for peritoneal staging compared with CT (75 %) and FDG-PET/CT (71 %). WB-DWI/MRI and FDG-PET/CT showed higher accuracy of 87 % for detecting retroperitoneal lymphadenopathies compared with CT (71 %). WB-DWI/MRI showed excellent correlation with FDG-PET/CT (κ?=?1.00) for detecting distant metastases compared with CT (κ?=?0.34). Interobserver agreement was moderate to almost perfect (κ?=?0.58–0.91).

Conclusions

WB-DWI/MRI shows high accuracy for characterising primary tumours, peritoneal and distant staging compared with CT and FDG-PET/CT and may be valuable for assessing operability in ovarian cancer patients.

Key Points

? Whole-body MRI with diffusion weighting (WB-DWI/MRI) helps to assess the operability of suspected ovarian cancer. ? Interobserver agreement is good for primary tumour characterisation, peritoneal and distant staging. ? WB-DWI/MRI improves mesenteric/serosal metastatic spread assessment compared with CT and FDG-PET/CT. ? Retroperitoneal/cervical-thoracic nodal staging using qualitative DWI criteria was reasonably accurate. ? WB-DWI/MRI and FDG-PET/CT showed the highest diagnostic impact for detecting thoracic metastases.     

Grading of Cerebral Glioma with Multiparametric MR Imaging and 18F-FDG-PET: Concordance and Accuracy

Objectives

To retrospectively evaluate concordance rates and predictive values in concordant cases among multiparametric MR techniques and FDG-PET to grade cerebral gliomas.

Methods

Multiparametric MR imaging and FDG-PET were performed in 60 consecutive patients with cerebral gliomas (12 low-grade and 48 high-grade gliomas). As the dichotomic variables, conventional MRI, minimum apparent diffusion coefficient in diffusion-weighted imaging, maximum relative cerebral blood volume ratio in perfusion-weighted imaging, choline/creatine ratio and (lipid and lactate)/creatine ratio in MR spectroscopy, and maximum standardised uptake value ratio in FDG-PET in low- and high-grade gliomas were compared. Their concordance rates and positive/negative predictive values (PPV/NPV) in concordant cases were obtained for the various combinations of multiparametric MR techniques and FDG-PET.

Results

There were significant differences between low- and high-grade gliomas in all techniques. Combinations of two, three, four, and five out of the five techniques showed concordance rates of 77.0?±?4.8 %, 65.5?±?4.0 %, 58.3?±?2.6 % and 53.3 %, PPV in high-grade concordant cases of 97.3?±?1.7 %, 99.1?±?1.4 %, 100.0?±?0 % and 100.0 % and NPV in low-grade concordant cases of 70.2?±?7.5 %, 78.0?±?6.0 %, 80.3?±?3.4 % and 80.0 %, respectively.

Conclusion

Multiparametric MR techniques and FDG-PET have a concordant tendency in a two-tiered classification for the grading of cerebral glioma. If at least two examinations concordantly indicated high-grade gliomas, the PPV was about 95 %.

Key Points

? Modern imaging techniques can help predict the aggressiveness of cerebral gliomas. ? Multiparametric MRI and FDG-PET have a concordant tendency to grade cerebral gliomas. ? Their high-grade concordant cases revealed at least 95 % positive predictive values. ? Their low-grade concordant cases revealed about 70–80 % negative predictive values.     

Evaluation of dynamic contrast-enhanced T1-weighted perfusion MRI in the differentiation of tumor recurrence from radiation necrosis

Introduction

To investigate if perfusion measured with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can be used to differentiate radiation necrosis from tumor recurrence in patients with high-grade glioma.

Methods

The study was approved by the institutional review board and informed consent was obtained from all subjects. 19 patients were recruited following surgery and radiation therapy for glioma. Patients had contrast enhancing lesions, which during the standard MRI examination could not be exclusively determined as recurrence or radiation necrosis. DCE-MRI was used to measure cerebral blood volume (CBV), blood–brain barrier (BBB) permeability and cerebral blood flow (CBF). Subjects also underwent FDG-PET and lesions were classified as either metabolically active or inactive. Follow-up clinical MRI and lesion histology in case of additional tissue resection was used to determine whether lesions were regressing or progressing.

Results

Fourteen enhancing lesions could be classified as progressing (11) or regressing (three). An empirical threshold of 2.0 ml/100 g for CBV allowed detection of regressing lesions with a sensitivity of 100 % and specificity of 100 %. FDG-PET and DCE-MRI agreed in classification of tumor status in 13 out of the 16 cases where an FDG-PET classification was obtained. In two of the remaining three patients, MRI follow-up and histology was available and both indicated that the DCE-MRI answer was correct.

Conclusion

CBV measurements using DCE-MRI may predict the status of contrast enhancing lesions and give results very similar to FDG-PET with regards to differentiation between tumor recurrence and radiation necrosis.     

Voxel-based comparison of preoperative FDG-PET between mesial temporal lobe epilepsy patients with and without postoperative seizure-free outcomes

Objective

This study aims to elucidate differences in preoperative cerebral glucose metabolism between patients who did and did not become seizure free after unilateral mesial temporal lobe epilepsy (mTLE) surgery. We hypothesized that regional glucose metabolism on preoperative fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with seizure-free outcomes differed from that in patients who were not seizure free after appropriate epilepsy surgery for unilateral mTLE. In this study, we compared preoperative FDG-PET findings between these two patient groups by applying a statistical analysis approach, with a voxel-based Asymmetry index (AI), to improve sensitivity for the detection of hypometabolism.

Methods

FDG-PET scans of 28 patients with medically refractory mTLE, of whom 17 achieved a seizure-free outcome (Engel class 1 a?Cb) during a postoperative follow-up period of at least 2?years, were analyzed retrospectively. Voxel values were adjusted by the AI method as well as the global normalization (GN) method. Two types of statistical analysis were performed. One was a voxel severity analysis with comparison of voxel values at the same coordinate, and the other was extent analysis with comparison of the number of significant voxels in the anatomical areas predefined with Talairach??s atlas.

Results

In the voxel severity analysis, significant hypometabolism restricted to the ipsilateral temporal tip and hippocampal area was detected in the postoperative seizure-free outcome group as compared to controls. No significant area was detected in the non-seizure-free group as compared to controls (family-wise error corrected, p?<?0.05). With extent analysis using a low threshold, the extents of hypometabolism in the ipsilateral hippocampal, frontal and thalamic areas were larger in the seizure-free than in the non-seizure-free group (p?=?0.01, 0.03 and 0.01, respectively.) On the other hand, in the contralateral frontal and thalamic areas, extents of hypometabolism were smaller in the seizure-free than in the non-seizure-free group (p?=?0.01 and 0.01).

Conclusions

We found the preoperative distribution of hypometabolism to differ between the two patient groups. Severe hypometabolism restricted to the unilateral temporal lobe, with ipsilateral dominant hypometabolism including mild decreases, may support the existence of an epileptogenic focus in the unilateral temporal lobe and a favorable seizure outcome after mTLE surgery.     

Evaluation of disease activity in ankylosing spondylitis; diagnostic value of color Doppler ultrasonography

Introduction

Spondyloarthropathies including ankylosing spondylitis (AS) require early diagnosis to prevent irreversible changes. Sacroiliitis is a common initial manifestation of AS and is frequently diagnosed by magnetic resonance imaging (MRI). The goal of our study was to assess color Doppler ultrasonography as a potential diagnostic tool in suspected sacroiliitis in comparison with MRI representing the gold standard.

Materials and methods

Fifty-one consecutive patients with AS and sacroiliitis and 30 control subjects underwent contrast-enhanced MRI and high resolution color Doppler and duplex ultrasonography of both sacroiliac joints (SIJ) for the detection of vascularization and blood flow spectral Doppler waveform analysis.

Results

MRI demonstrated active disease in 27 and inactive disease in 24 patients. CDUS detected pulsatile monophasic wave spectral waveform flow in 22 patients with the active disease, and triphasic in 7 patients with inactive disease and in 8 control patients. The sensitivity, specificity, positive predictive value and negative predictive value for active sacroiliitis detection with CDUS were 82 % (95 % CI, 68–91 %), 92 % (95 % CI, 85–96 %), 91 % (95 % CI, 84–96 %), and 84 % (95 % CI, 70–92 %), respectively, for pulsatile monophasic wave spectral waveform Doppler sonography. MRI of SIJ was negative in all 30 (60 SIJ) control participants.

Conclusions

Our results show that CDUS is a practical and useful tool in the diagnosis of active sacroiliitis.     

Secondary imaging for suspected appendicitis after equivocal ultrasound: time to disposition of MRI compared to CT

Purpose

The purpose of this study was to compare MRI to CT as a secondary imaging modality for children age 5 years and older with suspected appendicitis after an equivocal abdominal ultrasound in terms of (1) the time to ED disposition decision, (2) surgery consultation rate, and (3) imaging test accuracy.

Methods

We retrospectively studied children with suspected appendicitis and equivocal ultrasound results who underwent MR or CT as secondary imaging in a pediatric emergency department over two-consecutive 9-month periods. No oral or intravenous contrast was utilized for MRI. No sedation was utilized for any modality. Time of disposition is the time to admission or discharge order.

Results

Twenty-five patients underwent CT and 30 underwent MRI, with no significant difference in the median time from ultrasound to disposition between the CT (5.9 h, IQR 4.5, 8.4) and the MRI (5.9 h, IQR 4.6, 6.9) groups (p?= 0.65). Fifteen patients had appendicitis. Of the 40 negative or equivocal studies, surgery was consulted for 79% in the CT and 48% in the MRI group (odds ratio 4.12, 95% CI 1.02–16.67). Diagnostic accuracy was as follows: MRI: sensitivity of 90%, specificity of 97.1%, positive predictive value of 90%, and negative predictive value of 97.1%. Abdominal CT: sensitivity of 88%, specificity of 98.6%, positive predictive value of 95.7%, and negative predictive value of 95.8%.

Conclusion

MRI is a feasible alternative to CT for secondary imaging in acute appendicitis for showing comparable ED throughput metrics and diagnostic accuracy, with added benefits of reduced radiation and avoidance of intravenous contrast.

     

Feasibility of FDG-PET in myocarditis: Comparison to CMR using integrated PET/MRI

Objective

Besides cardiac sarcoidosis, FDG-PET is rarely used in the diagnosis of myocardial inflammation, while cardiac MRI (CMR) is the actual imaging reference for the workup of myocarditis. Using integrated PET/MRI in patients with suspected myocarditis, we prospectively compared FDG-PET to CMR and the feasibility of integrated FDG-PET/MRI in myocarditis.

Methods

A total of 65 consecutive patients with suspected myocarditis were prospectively assessed using integrated cardiac FDG-PET/MRI. Studies comprised T2-weighted imaging, late gadolinium enhancement (LGE), and simultaneous PET acquisition. Physiological glucose uptake in the myocardium was suppressed using dietary preparation.

Results

FDG-PET/MRI was successful in 55 of 65 enrolled patients: two patients were excluded due to claustrophobia and eight patients due to failed inhibition of myocardial glucose uptake. Compared with CMR (LGE and/or T2), sensitivity and specificity of PET was 74% and 97%. Overall spatial agreement between PET and CMR was κ = 0.73. Spatial agreement between PET and T2 (κ = 0.75) was higher than agreement between PET and LGE (κ = 0.64) as well as between LGE and T2 (κ = 0.56).

Conclusion

In patients with suspected myocarditis, FDG-PET is in good agreement with CMR findings.

     

Clinical value of a high-fat and low-carbohydrate diet before FDG-PET/CT for evaluation of patients with suspected cardiac sarcoidosis

Background

We hypothesized that a high-fat and low-carbohydrate (HFLC) diet before FDG-PET/CT could identify patients with active cardiac sarcoidosis (CS).

Methods

Fifty-eight sarcoidosis patients with a suspicion of CS consumed a HFLC diet before FDG-PET/CT. Clinical, electrical, and other imaging investigations were compared to PET results.

Results

Using Japanese Ministry of Health and Welfare (JMHW) criteria as a gold standard, 21% (12/58) of patients had a CS. Sensitivity and specificity of PET (visual analysis) were 83% (10/12) and 78% (36/46), respectively, with a very good interobserver agreement (k = 0.86). 70% (7/10) of the patients with a positive PET and negative JMHW criteria exhibited abnormalities suggestive of CS either on MR (n = 3) or SPECT (n = 4). Comparison with the presence of delayed enhancement on magnetic resonance imaging helped to classify patients with active (PET positive) or non-active CS (PET negative). In addition, when MR and PET were both negative, none of the patients met the JMHW criteria. PET response under treatment was concordant with clinical evolution in 11/13 patients.

Conclusions

FDG-PET/CT after HFLC diet is a sensitive tool for the diagnosis of active CS. Combined use of PET and MR is promising for the detection and characterization of CS lesions.     

Whole-body MRI for initial staging of paediatric lymphoma: prospective comparison to an FDG-PET/CT-based reference standard

Objective

To compare whole-body MRI, including diffusion-weighted imaging (whole-body MRI-DWI), with FDG-PET/CT for staging newly diagnosed paediatric lymphoma.

Methods

A total of 36 children with newly diagnosed lymphoma prospectively underwent both whole-body MRI-DWI and FDG-PET/CT. Whole-body MRI-DWI was successfully performed in 33 patients (mean age 13.9 years). Whole-body MRI-DWI was independently evaluated by two blinded observers. After consensus reading, an unblinded expert panel evaluated the discrepant findings between whole-body MRI-DWI and FDG-PET/CT and used bone marrow biopsy, other imaging data and clinical information to derive an FDG-PET/CT-based reference standard.

Results

Interobserver agreement of whole-body MRI-DWI was good [all nodal sites together (κ = 0.79); all extranodal sites together (κ = 0.69)]. There was very good agreement between the consensus whole-body MRI-DWI- and FDG-PET/CT-based reference standard for nodal (κ = 0.91) and extranodal (κ = 0.94) staging. The sensitivity and specificity of consensus whole-body MRI-DWI were 93 % and 98 % for nodal staging and 89 % and 100 % for extranodal staging, respectively. Following removal of MRI reader errors, the disease stage according to whole-body MRI-DWI agreed with the reference standard in 28 of 33 patients.

Conclusions

Our results indicate that whole-body MRI-DWI is feasible for staging paediatric lymphoma and could potentially serve as a good radiation-free alternative to FDG-PET/CT.

Keypoints

? Accurate staging is important for treatment planning and assessing prognosis ? Whole-body MRI-DWI could be a good radiation-free alternative to FDG-PET/CT ? Interobserver agreement of whole-body MRI-DWI is good ? Agreement between whole-body MRI and the FDG-PET/CT reference standard is good ? Most discrepancies were caused by suboptimal accuracy of size measurements on MRI     

Diagnostic value of pelvic enthesitis on MRI of the sacroiliac joints in spondyloarthritis

Objective

To determine the prevalence and diagnostic value of pelvic enthesitis on MRI of the sacroiliac (SI) joints in spondyloarthritis (SpA).

Materials and methods

A retrospective study in 444 patients aged 17–45 years old with MRI of the SI joints and with clinically suspected sacroiliitis was performed. Patients were classified as having SpA if they fulfilled the Assessment of Spondyloarthritis International Society (ASAS) criteria. Pelvic enthesitis on MRI was correlated with the final diagnosis. Sensitivity, specificity, positive and negative likelihood ratio (LR) and predictive values (PV) of pelvic enthesitis for the diagnosis of SpA were calculated.

Results

MRI showed pelvic enthesitis in 24.4 % of patients with SpA and in 7.1 % of patients without SpA. Presence of any enthesitis had sensitivity, specificity, LR+, LR?, PPV and NPV of 24.4 %, 92.9 %, 3.45, 0.81, 69.4 % and 65.2 % for the diagnosis of SpA, respectively. The most commonly affected entheses were the longitudinal ligament insertion (4.5 %), the retroarticular ligaments (4.1 %) and the pubic symphysis (4.1 %). The sites of enthesitis with the highest PPV for SpA were the iliac crest/wing (85.7 %) and the retroarticular ligaments (81.3 %).

Conclusion

Nearly one fourth of SpA patients with suspected sacroiliitis showed pelvic enthesitis on MRI. Such pelvic enthesitis has a high specificity for the diagnosis of spondyloarthritis.

Key Points

? Enthesitis is the primary clinical feature of spondyloarthritis. ? Magnetic resonance imaging of the sacroiliac joints can demonstrate pelvic enthesitis. ? Pelvic enthesitis has a high specificity for the diagnosis of spondyloarthritis.     

Is the type and extent of hippocampal sclerosis measurable on high-resolution MRI?

Introduction

The purpose of this study is to relate hippocampal volume and FLAIR signal intensity to Wyler grading of hippocampal sclerosis (HS).

Methods

Of 100 consecutive patients with temporal lobe epilepsy and HS as histopathological diagnosis, 32 had high-resolution 3 Tesla MRI and anatomically well-preserved hippocampi following amygdalo-hippocampectomy. Hippocampal volume on 3D T1-weighted gradient echo and signal intensity on coronal FLAIR sequences were determined using FreeSurfer and SPM tools and related to Wyler grading. Seizure outcome was determined after 1 year.

Results

Histopathology showed four Wyler II, 19 Wyler III, and 9 Wyler IV HS. Hippocampal volumes were 3.08 ml for Wyler II (Wyler II/contralateral side: p?>?0.05), 2.19 ml for Wyler III (p?p?=?0.01), and 3.08 ml for the contralateral side. Normalized FLAIR signals were 1,354 (p?=?0.0004), 1,408 (p?p?Conclusions Combined volumetry and quantitative FLAIR signal analysis clearly identifies Wyler III and IV HS. Quantitative FLAIR signal analysis may be helpful to identify Wyler II HS.     

F-18 FDG-PET/CT in evaluation of patients with fever of unknown origin

Objectives

This study was carried out to evaluate the diagnostic utility of FDG-PET/CT in patients with fever of unknown origin (FUO).

Methods

Medical records of 103 patients who underwent FDG-PET/CT and anatomic imaging as a part of FUO workup were analyzed. Final diagnosis of the cause of FUO was reached based on serologic assays, cultures, biopsy, surgery or 6 months of clinical follow-up.

Results

The definite cause of fever was established in 69/103 patients. Abnormal FDG uptake was found in 63/103 patients and contributed to the final diagnosis (TP) in 62 patients (98.48 %). Of the remaining 40 patients with negative PET/CT, the final definite cause of fever (FN) could be determined only in seven patients (17.5 %). PET/CT had a sensitivity, specificity, positive predictive value and negative predictive value of 90, 97, 98.4 and 82.5 % compared to 43.5, 67.6, 73.2 and 37.1 %, respectively, for anatomic imaging. FDG-PET/CT had a higher accuracy (92.2 vs. 51.5 %; p = 0.003) compared to anatomic imaging for suggesting a cause of FUO.

Conclusions

PET/CT showed high sensitivity and specificity in suggesting a definite diagnosis in the evaluation of FUO.