Mario Piga

Role of SPECT/CT in the preoperative assessment of hyperparathyroid patients

Purpose.Our purpose was to assess the clinical value and additional benefit of fusion single-photon computed tomography (SPECT) and computed tomography (CT) images in locating the parathyroids in a selected group of patients affected by primary (PHP) and secondary hyperparathyroidism (SHP).Materials and methods.Sixteen patients (11 women and five men; age range 35–80 years) with severe hyperparathyroidism (HP) (ten PHP, six SHP) were studied by ultrasound (US), and, after i.v. injection of 370 MBq of 99mTc-sestamibi, by planar parathyroid scintigraphy, SPECT and SPECT/CT using a dualdetector scintillation camera GE Infinia Hawkeye. All patients underwent parathyroidectomy.Results.US findings were inconclusive in 12/16 patients affected by multinodular goitre, and two probable eutopic parathyroid glands were identified. “Double phase” parathyroid scintigraphy identified 14 probable parathyroid glands, SPECT 23 (14 ectopic and nine eutopic) and SPECT/CT confirmed all 23 probable parathyroid lesions, offering more precise localisation and an evident improvement in diagnostic accuracy. Sixteen of these foci of increased uptake were hyperplastic parathyroid glands, six were adenomas, one was a parathyroid carcinoma and one was a thyroid follicular carcinoma. Surgical detection of the 23 sestamibi-positive lesions was correctly matched with 100% of SPECT/CT images and 61% of SPECT data alone. Hybrid imaging thus provided additional data in 39% of lesions, and in three patients with retrotracheal glands, it modified the surgical approach.Conclusions.We believe 99mTc-sestambi SPECT/CT to be a more reliable presurgical method to study a patient subgroup affected by PHP or SHP in whom conventional US and other scintigraphic methods have failed for intrinsic reasons due to the concomitant presence of multinodular goitre or ectopic parathyroid gland. The additional practical benefit derived from this methodology was evident. In fact, anatomical information provided by CT enables precise localisation of the functional abnormalities highlighted by SPECT, and both are essential to a correct surgical approach.

Comparison of MRI, EEG, EPs and ECD-SPECT in Wilson's disease

Objectives – The purpose of this study is to evaluate the efficiency of a few methodologies in detecting anatomo‐functional brain abnormalities in patients with Wilsons disease. Materials and methods – Twenty‐three patients with Wilsons disease underwent almost simultaneously brain magnetic resonance imaging (MRI), computerized electroencephalography (EEG), multimodal evoked potentials (EPs) and ECD single photon computerized tomography (SPECT) evaluation. The clinical picture was of the neurologic type in 8 patients and of the hepatic type in 15. Results – MRI was abnormal in 7 patients with neurological manifestations. The EPs proved pathologic in 7 neurologically symptomatic patients and in 4 cases with hepatic form. These results agree with those reported in other case studies. The EEG records were abnormal only in 3 cases. Nevertheless, the most interesting finding of this study is the particular frequency (86%) of diffuse or focal decrease of ECD uptake shown by brain SPECT. Conclusion – We highlight the use of this interesting procedure in the therapeutic monitoring of this disease.

Imaging of the Carotid Artery Vulnerable Plaque

AbstractAtherosclerosis involving the carotid arteries has a high prevalence in the population worldwide. This condition is significant because accidents of the carotid artery plaque are associated with the development of cerebrovascular events. For this reason, carotid atherosclerotic disease needs to be diagnosed and those determinants that are associated to an increased risk of stroke need to be identified. The degree of stenosis typically has been considered the parameter of choice to determine the therapeutical approach, but several recently published investigations have demonstrated that the degree of luminal stenosis is only an indirect indicator of the atherosclerotic process and that direct assessment of the plaque structure and composition may be key to predict the development of future cerebrovascular ischemic events. The concept of “vulnerable plaque” was born, referring to those plaque’s parameters that concur to the instability of the plaque making it more prone to the rupture and distal embolization. The purpose of this review is to describe the imaging characteristics of “vulnerable carotid plaques.”

Association between carotid plaque enhancement shown by multidetector CT angiography and histologically validated microvessel density

PurposeCarotid plaques analysed by MDCTA can show contrast enhancement. The purpose of this study was to explore the association between carotid plaque enhancement (CPE) and microvessel density.Materials and methodsWe obtained IRB approval. Twenty-nine consecutive (male, 20; median age, 63) symptomatic patients studied with 16-detector CT were prospectively analysed. Examinations were performed before and after intravenous contrast medium administration, and analysis of plaque enhancement was performed. Patients underwent “en bloc” carotid endarterectomy; histological sections were prepared and the presence of microvessels quantified. Logistic regression analysis as well as ROC curve and area under the curve was calculated.ResultsA statistically significant association between the degree of CPE and microvessel density (P = 0.009; rho = 0.553) was observed. The ROC curve analysis confirmed this association with an area under the curve of 0.906, 0.735, 0.644 and 0.546 for CPE of 10 HU, 15 HU, 20 HU and 25 HU respectively. There was a statistically significant difference between the CPE and the degree of neovascularisation (P = 0.0003).ConclusionResults of this preliminary study suggest that CPE might be associated with the microvessel density. Histological analysis seems to demonstrate that the degree of intra-plaque neo-vascularisation is statistically associated with CPE.Key PointsCarotid artery plaque enhancement at CT is associated with microvessel density.The degree of intra-plaque neo-vascularisation is statistically associated with carotid plaque enhancement.Plaque enhancement at CT should be considered when assessing vulnerable plaques.

Carotid Artery Plaque Characterization Using CT Multienergy Imaging

BACKGROUND AND PURPOSE: Carotid artery plaque types can be categorized with CT according to their HU values. The purpose of this work was to analyze carotid artery plaque characteristics by using multienergy imaging. METHODS AND MATERIALS: Thirty-two consecutive patients (23 men; median age, 70 years) were retrospectively analyzed. Carotid arteries were studied with a multienergy CT scanner. All patients received a 15-mL timing bolus of contrast medium to synchronize the data acquisition followed by an injection of 60 mL of contrast medium at a 5-mL/s flow rate. Plaque analysis in 64 carotid arteries was performed, and datasets were reconstructed by using a dedicated workstation. For each plaque, the HU value was quantified with a 2-mm-square region of interest at monoenergy values of 66, 70, 77, and 86 keV. The Wilcoxon test was used to test the differences in HU values in the plaques at different kiloelectron volts. RESULTS: Four carotid arteries were excluded due to the absence of plaque, and another 7, because of the presence of calcified plaques. In the remaining 53 carotid arteries, Wilcoxon analysis showed a statistically significant difference in HU values among the monoenergy values of 66, 70, 77, and 86 keV (P = .0001). In particular, we found that with the increase in monochromatic kiloelectron volt values, there is a statistically significant reduction in the HU value of the plaque. CONCLUSIONS: Results of this study suggest that the HU values of plaque may significantly change according to the selected kiloelectron volt; therefore, the HU-based plaque type (fatty, mixed, calcified) should be classified according to the energy level applied.

Molecular analysis of patients of Sardinian descent with Crigler-Najjar syndrome type I.

This study reports the molecular characterisation of the bilirubin UDP-glucuronosyl-transferase gene (UGT1) in a group of patients of Sardinian descent with Crigler-Najjar syndrome type I and their relatives. Sequence analysis of both UGT1A exon 1 and common exons 2-5 was performed in all patients, leading to the detection of AF170 and a novel mutation (470insT), both residing in UGT1A exon 1. All but two heterozygotes for the AF170 mutation showed normal serum bilirubin levels. These two subjects were also heterozygous for the sequence variation A(TA)7TAA in the promoter region of the UGT1A gene.

Carotid Artery Plaque Classification: Does Contrast Enhancement Play a Significant Role?

BACKGROUND AND PURPOSE: Previous articles have demonstrated that carotid artery plaques may have enhancement after administration of contrast material. The purpose of this study was to evaluate the effect of enhancement in carotid artery classification. MATERIALS AND METHODS: Three hundred eighty consecutive patients (235 men, 145 women; median age 64, age range 32–87 years) were analyzed using a multidetector row CT scanner. Examinations were performed before and after CM administration. Carotid artery plaques with a attenuation value <60 HU were considered fatty, those from 60–130 HU were considered mixed, and those >130 HU were considered calcified. χ2 tests, Student t tests, and Cohen analyses were performed. RESULTS: Before CM administration, we observed 226 calcified, 175 mixed, and 206 fatty plaques; after CM administration, 229 calcified, 213 mixed, and 165 fatty plaques were observed. A statistically significant difference between these 2 groups was observed (P = .016). We found that 19.9% of fatty plaques become mixed (n = 41), whereas 1.7% of the mixed plaques become calcified (n = 3). All calcified plaques remained in the same category. Fatty plaques that changed type showed a larger enhancement compared with those that remained in the same class (P = .001). Cohen analyses showed very good agreement between observers before (κ = 0.834) and after contrast material administration (κ = 0.86). CONCLUSIONS: The results of this study indicate that the carotid artery plaques (fatty and mixed) significantly change according to whether analysis is performed before or after administration of contrast material.

Association Between the Volume of Carotid Artery Plaque and Its Subcomponents and the Volume of White Matter Lesions in Patients Selected for Endarterectomy

OBJECTIVE The amount of cerebral white matter lesions (WMLs) and the severity of carotid artery disease are correlated in this study. The association between the severity of WMLs and the volume of the different components of carotid artery plaque is also evaluated. MATERIALS AND METHODS Fifty consecutive patients (39 men, 11 women; mean [SD] age, 71 ± 9 years) with carotid artery stenosis who underwent carotid endarterectomy were included in this study. On admission, patients underwent head and neck CT angiography (CTA) and brain MRI. The CTA-based plaque volume and the percentages of the three main plaque components (fatty, mixed, and calcified) were calculated according to the attenuation values. Leukoaraiosis lesion volume on FLAIR images was determined using a semiautomated segmentation technique. Pearson correlation was conducted between the leukoaraiosis lesion volume on FLAIR images and the volumes of the different plaque components. RESULTS Pearson correlation analysis was performed to determine WML volume versus total carotid plaque volume (ρ = 0.2531; p = 0.0262), fatty plaque volume (ρ = 0.387; p = 0.0005), mixed plaque volume (ρ = 0.1709; p = 0.15), and calcified plaque volume (ρ = 0.0146; p = 0.899). The WML volume was also compared against fatty plaque percentage (ρ = 0.343; p = 0.0018), mixed plaque percentage (ρ = 0.181; p = 0.124), and calcified plaque percentage (ρ = -0.209; p = 0.068). CONCLUSION The cerebral WML volume and the total volume of the plaque are correlated. The amount of fat within the plaque is an additional risk factor, whereas the calcified component seems to be protective.

Endometriosis: the role of magnetic resonance imaging

Several imaging options are available today to diagnose endometriosis. Currently, the two techniques most used are sonography and magnetic resonance imaging (MRI). Three-dimensional (3D) sonography has proved to be particularly sensitive in the diagnosis of endometriosis. In recent years, MRI has emerged as a high reproducible method to explore endometriosis; moreover, its capability to evaluate tissue signal is an extremely powerful system in the differential diagnosis with other pathologies and for the identification of malignant degeneration. The purpose of this paper is to present the state-of-the-art of MRI of endometriosis by performing a review of the literature and showing the epidemiology, pathogenesis, and classification of endometriosis. In this work, the technique that should be used, MR findings of endometriosis and the principles of differential diagnosis are explained.

Correlation between Fissured Fibrous Cap and Contrast Enhancement: Preliminary Results with the Use of CTA and Histologic Validation

BACKGROUND AND PURPOSE: Previous studies demonstrated that carotid plaques analyzed by CTA can show contrast plaque enhancement. The purpose of this preliminary work was to evaluate the possible association between the fissured fibrous cap and contrast plaque enhancement. MATERIALS AND METHODS: Forty-seven consecutive (men = 25; average age = 66.8 ± 9 years) symptomatic patients studied by use of a multidetector row CT scanner were prospectively analyzed. CTA was performed before and after contrast and radiation doses were recorded; analysis of contrast plaque enhancement was performed. Patients underwent carotid endarterectomy en bloc; histologic sections were prepared and evaluated for fissured fibrous cap and microvessel attenuation. The Mann-Whitney test was performed to evaluate the differences between the 2 groups. A multiple logistic regression analysis was performed to assess the effect of fissured fibrous cap and microvessel attenuation on contrast plaque enhancement. Receiver operating characteristic curve and area under the curve were also calculated. RESULTS: Twelve patients had fissured fibrous cap. In 92% (11/12) of fissured fibrous cap–positive plaques, we found contrast plaque enhancement, whereas in 69% (24/35) of the plaques without fissured fibrous cap contrast plaque enhancement was found. The Mann-Whitney test showed a statistically significant difference between the contrast enhancement in plaques with fissured fibrous cap (Hounsfield units = 22.6) and without fissured fibrous cap (Hounsfield units = 12.9) (P = .011). On the regression analysis, both fissured fibrous cap and neovascularization were associated with contrast plaque enhancement (P = .0366 and P = .0001). The receiver operating characteristic curve confirmed an association between fissured fibrous cap and contrast plaque enhancement with an area under the curve of 0.749 (P = .005). CONCLUSIONS: The presence of fissured fibrous cap is associated with contrast plaque enhancement. Histologic analysis showed that the presence of fissured fibrous cap is associated with a larger contrast plaque enhancement compared with the contrast plaque enhancement of plaques without fissured fibrous cap.