MSCT versus CBCT: evaluation of high-resolution acquisition modes for dento-maxillary and skull-base imaging.

OBJECTIVES: Our aim was to conduct a quantitative and qualitative evaluation of high-resolution skull-bone imaging for dentistry and otolaryngology using different architectures of recent X-ray computed tomography systems. MATERIAL AND METHODS: Three multi-slice computed tomography (MSCT) systems and one Cone-beam computed tomography (CBCT) system were used in this study. All apparatuses were tested with installed acquisition modes and proprietary reconstruction software enabling high-resolution bone imaging. Quantitative analyses were performed with small fields of view with the preclinical vmCT phantom, which permits to measure spatial resolution, geometrical accuracy, linearity and homogeneity. Ten operators performed visual qualitative analyses on the vmCT phantom images, and on dry human skull images. RESULTS: Quantitative analysis showed no significant differences between protocols in terms of linearity and geometric accuracy. All MSCT systems present a better homogeneity than the CBCT. Both quantitative and visual analyses demonstrate that CBCT acquisitions are not better than the collimated helical MSCT mode. CONCLUSION: Our results demonstrate that current high-resolution MSCT protocols could exceed the performance of a previous generation CBCT system for spatial resolution and image homogeneity. KEY POINTS: • Quantitative evaluation is a prerequisite for comparison of imaging equipment. • Bone imaging quality could be objectively assessed with a phantom and dry skull. • The current MSCT shows better image quality than a dental CBCT system. • CBCT remains a work-in-progress technology.

The impact of dialysis solution biocompatibility on ultrafiltration and on free water transport in rats.

This study compares different peritoneal dialysis fluids (PDF) in rats over a short contact time. For greater accuracy, net ultrafiltration (UF) and peritoneal transport indices, mass transfer area coefficient (MTAC) were scaled for the in vivo peritoneal surface area recruited (ivPSA) measured by microcomputerized tomography. Wistar rats underwent nephrectomy (5/6ths), were randomized into two groups and given 1.5% glucose PDF, either conventional acidic lactate (n = 14) or pH neutral bicarbonate (BicaVera) (n = 13); MTAC and UF were measured using a 90-min peritoneal equilibrium test (PET), fill volume (IPV) of 10 ml/100 g; small pore fluid transport was determined from sodium balance and used to calculate free water transport (FWT). Each ivPSA value was significantly correlated with the actual IPV, which varied from one rat to another. At 90 min of contact, there was no difference in recruited ivPSA in relation to PDFs. There was a difference (p < 0.01) in net UF/ivPSA 0.45 vs. 1.41 cm(2)/ml for bicarbonate versus lactate, as there was in the proportion of FWT with bicarbonate (42 ± 5% of net UF) compared to lactate (29 ± 4% of net UF). Net UF for individual values of ivPSA differs between conventional PDF and more biocompatible solutions, such as bicarbonate PDF. This observed change in UF cannot be fully explained by differences in glucose transport. The changes in FWT may be explained by the impact of the PDF biocompatibility on aquaporin function.

Frequent, quantitative bone planar scintigraphy for determination of bone anabolism in growing mice.

BACKGROUND: To provide insight into bone turnover, quantitative measurements of bone remodeling are required. Radionuclide studies are widely used in clinical care, but have been rarely used in the exploration of the bone in preclinical studies. We describe a bone planar scintigraphy method for frequent assessment of bone activity in mice across the growing period. Since repeated venous radiotracer injections are hardly feasible in mice, we investigated the subcutaneous route. METHODS: Repeated 99mTc-hydroxymethylene diphosphonate (HMDP) tracer bone planar scintigraphy studies of the knee region and µCT to measure femur growth rate were performed in eight mice between week 6 and week 27 of life, i.e., during their growth period. Three independent investigators assessed the regions of interest (ROI). An index was calculated based on the counts in knees ROI (normalized by pixels and seconds), corrected for the activity administered, the decay between administration and imaging, and individual weights. RESULTS: A total of 93 scintigraphy studies and 85 µCT were performed. Repeated subcutaneous tracer injections were well tolerated and allowed for adequate radionuclide studies. Mean scintigraphic indexes in the knees ROI decreased from 87.4 ± 2.6 × 10-6 counts s-1 pixel-1 MBq-1 g-1 at week 6 to 15.0 ± 3.3 × 10-6 counts s-1 pixel-1 MBq-1 g-1 at week 27. The time constant of the fitted exponential decay was equal to 23.5 days. As control mean femur length assessed by µCT increased from 12.2 ± 0.8 mm at week 6 to 15.8 ± 0.2 mm at week 22. The time constant of the fitted Gompertz law was equal to 26.7 days. A correlation index of -0.97 was found between femur growth and decrease of bone tracer activity count between week 6 and 24. CONCLUSION: This methodological study demonstrates the potential of repeated bone planar scintigraphy in growing mice, with subcutaneous route for tracer administration, for quantitative assessment of bone remodeling.

Importance of inflammation and neurohumoral activation in Takotsubo cardiomyopathy.

BACKGROUND: To gain more insight into the involvement of inflammatory response and neurohumoral activation in Takotsubo cardiomyopathy (TTC), we investigated C-reactive protein (CRP), leukocytes, plasma catecholamines levels, iodine 123 meta-iodobenzylguanidine (123I-mIBG) myocardial uptake, myocardial perfusion (thallium 201 [201Tl] or technetium [Tc] 99m-tetrofosmin myocardial single photon emission computed tomography [SPECT]), and metabolism (fluorine 18-fluorodeoxyglucose positron emission tomography). METHODS AND RESULTS: Inflammatory status and brain natriuretic peptide (BNP) levels in 17 patients with TTC were compared with 14 age-matched patients. In TTC, elevated levels of CRP were evidenced on admission, reaching a peak in the following days (P < .01). CRP levels were correlated to baseline left ventricular ejection fraction (LVEF) and BNP levels (P < .05). Leukocytes were correlated to BNP and noradrenaline levels. Myocardial 123I-mIBG SPECT showed a reduced activity in the midventricle and apex corresponding to 35% +/- 23% of the total myocardial mass, partially reversible at follow-up. An identical pattern was retrieved when assessing myocardial glucose metabolism. At rest, no relevant abnormalities of myocardial perfusion could be evidenced at the subacute phase. CONCLUSION: Inflammatory status in TTC was related to LVEF impairment and to the extent of neurohormonal activation. The hypothesis of a catecholamine-induced myocardial "stunning" is emphasized by the evidence of a reduced 123I-mIBG myocardial activity, impairment of myocardial glucose metabolism, and wall motion kinetic after the same temporospatial distribution.

SPECT low-field MRI system for small-animal imaging.

UNLABELLED: Localization of regions with increased uptake of radiotracer in small-animal SPECT is greatly facilitated when using coregistration with anatomic images of the same animal. As MRI has several advantages compared with CT (soft-tissue contrast and lack of ionizing radiation) we developed a SPECT/low-field MRI hybrid device for small-animal imaging. METHODS: A small-animal single-pinhole gamma-camera (pinhole, 1.5 mm in diameter and 12 cm in focal length) adjacent to a dedicated low-field (0.1 T) small MR imager (imaging volume, 10 x 10 x 6 cm(3)) was used. The animal was placed in a warmed nonmagnetic polymethyl methacrylate imaging cell for MR acquisition, which was followed immediately by SPECT after translation of the imaging cell from one modality to the other. 3-Dimensional T1-weighted sequences were used for MRI. Phantom studies enabled verification of a low attenuation (10%) for (99m)Tc and (201)Tl and a very slight increase in Compton scattering due to the radiofrequency coil and polymethyl methacrylate imaging cell. RESULTS: SPECT/MRI data acquisition and image coregistration of selected examples using different radiotracers for lungs, kidneys, and brain were obtained in 3 nude mice with isotropic spatial resolutions of 0.5 x 0.5 x 0.5 mm(3) for MRI and 1 x 1 x 1 mm(3) for SPECT. The total acquisition time for combined SPECT and MRI lasted 1 h 45 min. CONCLUSION: A low-magnetic-field strength of 0.1 T is a simple and useful solution for a small-animal dual-imaging device combining pinhole SPECT with the adjacent MR imager.

Assessment of right and left ventricular function in healthy mice by blood-pool pinhole gated SPECT.

The feasibility of blood-pool pinhole ECG gated SPECT was investigated in healthy mice to assess right and left ventricular function analysis. Anaesthetized (isoflurane 1-1.5%) adult CD1 mice (n=11) were analyzed after intravenous administration of 0.2 ml of 550 MBq of (99m)Tc human albumin. For blood-pool gated SPECT imaging, 48 ventral step and shoot projections with eight time bins per RR over 180 degrees with 64 x 64 word images were acquired with a small animal gamma camera equipped with a pinhole collimator of 12 cm in focal length and 1.5 mm in diameter. For appropriate segmentation of right and left ventricular volumes, a 4D Fourier analysis was performed after reconstruction and reorientation of blood-pool images with a voxel size of 0.55 x 0.55 x 0.55 mm(3). Average right and left ejection fractions were respectively 52+/-4.7% and 65+/-5.2%. Right end diastolic and end systolic volumes were significantly higher compared with the corresponding left ventricular volumes (P<0.0001 each). A linear correlation between right and left stroke volumes (r=0.9, P<0.0001) was obtained and right and left cardiac outputs were not significantly different 14.2+/-1.9 and 14.1+/-2 ml/min, respectively.

Assessment of in vivo and post-mortem mechanical behavior of brain tissue using magnetic resonance elastography.

The knowledge of in vivo brain tissue mechanical properties is essential in several biomedical engineering fields, such as injury biomechanics and neurosurgery simulation. Almost all existing available data have been obtained in vitro by invasive experimental protocols. However, the difference between in vivo and post-mortem mechanical properties remains poorly known, essentially due to the lack of a common method that could measure them both in vivo and ex vivo. In this study, we report the use of magnetic resonance elastography (MRE) for the non-invasive assessment of in vivo brain tissue viscoelastic properties and for the investigation of their evolution after the death. Experiments were performed on seven adult male rats. Shear storage and loss moduli were measured in vivo, just after death and at post-mortem time of approximately 24h. A significant increase in shear storage modulus G(') of approximately 100% was found to occur just after death (p=0.002), whereas no significant difference was found between in vivoG(') and G(') at 24h post-mortem time. No significant difference was found between shear loss modulus G('')in vivo and just after death, whereas a decrease of about 50% was found to occur after 24h (p=0.02). These results illustrate the ability of MRE to investigate some of the critical soft tissue biomechanics-related issues, as it can be used as a non-invasive tool for measuring soft tissue viscoelastic properties.

In vivo peritoneal surface area measurement in rats by micro-computed tomography (microCT).

Peritoneal dialysis (PD) uses the dynamic dialysis properties of the peritoneal membrane. The fraction of the anatomic peritoneal surface area (PSA) recruited is of importance for maximizing exchanges and is potentially impacted by parameters such as fill volume. We describe an in vivo assessment of the contact surface area by micro-computed tomography (microCT) using an iodinated contrast medium added to the PD fluid, a contrast agent presumed without surfactant property. In the isotropic volume (reconstructed voxel size 186 microm x 186 microm x 186 microm), the iodinated PD fluid is automatically selected, thanks to its contrast difference with soft tissues, and its surface area is computed. The method was first tested on phantoms showing the ability to select the PD fluid volume and to measure its surface area. In vivo experiments in rat consisted of microCT acquisition of rat abdomen directly after intraperitoneal administration (10 mL/100 g rat body weight) of a dialysis fluid containing 10% by volume iodinated contrast agent. Fluorescein isothiocyanate albumin was used as dilution marker. We found a strong linear relationship (R(2) = 0.98) between recruited PSA (cm(2)) and rat weight (g) in the range of 235 to 435 g: recruited PSA = (1.61 weight + 40.5) cm(2). Applying microCT with a fill volume of 10 mL/100 g rat body weight, the in vivo measured PSA was in the order of magnitude of the ex vivo anatomic PSA as determined by Kuzlan's formula, considered in most instances as the maximal surface area that can be recruited by PD fluid. This new methodology was the first to give an in vivo high-resolution isotropic three-dimensional (3-D) determination of the PSA in contact with dialysate. Its sensitivity allows us to take into account the recruitment of fine 3-D structures of the PSA membrane that were not accessible to previous 2-D-based imaging methodologies. Its in vivo application also integrates the physiological natural tensile stress of tissues.

Multiple-contrast X-ray micro-CT visualization of colon malformations and tumours in situ in living mice.

The development of new therapeutic approaches against colorectal cancer requires preclinical studies in mice. In vivo imaging could greatly facilitate these trials, but the small size of the animals is a major limitation for the direct visualization of intestinal tissue. Here we report a method of in vivo imaging of the mouse intestine based on X-ray micro-computed tomography using multiple contrast agents. This method was validated in the model of non-cancerous polyp-like heteroplasia that spontaneously develops in the caecum area of Cdx2+/- mutant mice and in the model of colon adenocarcinoma induced by administration of the chemical carcinogen azoxymethane. As a simple and non-invasive method, multiple-contrast X-ray micro-computed tomography is appropriate for pre-clinical studies of intestinal diseases in living mice.

[18F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography for early evaluation of treatment efficacy in advanced non-Hodgkin lymphoma of uterine corpus: a case report.

We report a case of diffuse large B-cell lymphoma occurring in a patient with the hyperimmunoglobulinemia E syndrome, a rare immune disorder defined by elevated immunoglobulin E levels and recurrent bacterial and fungal infections often manifesting as cold abscesses. This case further supports the notion that patients with hyperimmunoglobulinemia E have an increased risk of lymphoid malignancies and should be closely monitored. Despite a theoretic risk of severe infectious complications, chemotherapy was well tolerated and resulted in a sustained complete remission.

Influence of Animal Heating on PET Imaging Quantification and Kinetics: Biodistribution of 18F-Tetrafluoroborate and 18F-FDG in Mice.

Different environmental conditions under anesthesia may lead to unstable homeostatic conditions in rodents and therefore may alter kinetics. In this study, the impact of different heating conditions on PET imaging quantification was evaluated. Methods: Two groups of 6 adult female BALB/c nude mice with subcutaneously implanted tumors underwent microPET imaging after injection of 18F-labeled tetrafluoroborate or 18F-FDG. Dynamic scans were acquired under optimal and suboptimal heating conditions. Time-activity curves were analyzed to calculate uptake and washout time constants. Results: With 18F-labeled tetrafluoroborate, optimal animal heating led to a stable heart rate during acquisition (515 ± 35 [mean ± SD] beats/min), whereas suboptimal heating led to a lower heart rate and a higher SD (470 ± 84 beats/min). Both uptake and washout time constants were faster (P < 0.01) in animals maintained with optimal heating. Conclusion: Although the difference in heart rates was slight, optimal heating yielded significantly faster uptake and washout kinetics than suboptimal heating in all organs for both tracers.

Estimation of subject coregistration errors during multimodal preclinical imaging using separate instruments: origins and avoidance of artifacts.

We use high-resolution [Formula: see text] data in multiple experiments to estimate the sources of error during coregistration of images acquired on separate preclinical instruments. In combination with experiments with phantoms, we completed in vivo imaging on mice, aimed at identifying the possible sources of registration errors, caused either by transport of the animal, movement of the animal itself, or methods of coregistration. The same imaging cell was used as a holder for phantoms and animals. For all procedures, rigid coregistration was carried out using a common landmark coregistration system, placed inside the imaging cell. We used the fiducial registration error and the target registration error to analyze the coregistration accuracy. We found that moving an imaging cell between two preclinical devices during a multimodal procedure gives an error of about [Formula: see text] at most. Therefore, it could not be considered a source of coregistration errors. Errors linked to spontaneous movements of the animal increased with time, to nearly 1 mm at most, excepted for body parts that were properly restrained. This work highlights the importance of animal intrinsic movements during a multiacquisition procedure and demonstrates a simple method to identify and quantify the sources of error during coregistration.

Image quality evaluation of small FOV and large FOV CBCT devices for oral and maxillofacial radiology.

OBJECTIVES: Quantitative and qualitative image quality evaluation of two different dental CBCT scanners. METHODS: Two CBCT systems were evaluated in this study: one small field-of-view (FOV) (50-mm diameter) system that also allows two-dimensional (2D) dental panoramic imaging and one large FOV CBCT system (60-180-mm diameter). These devices were all tested with installed acquisition default modes and proprietary reconstruction software, enabling high-resolution bone imaging. Quantitative analyses were carried out to measure spatial resolution, linearity and homogeneity. Small-size phantoms and a human dry skull were used to evaluate intrinsic performances. Visual qualitative analyses of specific anatomical parts were blindly performed by 10 operators. RESULTS: Concerning spatial resolution, small-voxel size protocols provide equivalent results on the two apparatus. In terms of linearity, all systems are highly linear (0.98 < r2 < 0.99) over the range of signal intensities encountered. Our results, coming from either phantoms or the dry skull, demonstrate that the small FOV CBCT suffers from a lack of homogeneity. CONCLUSIONS: For limited oral and maxillofacial volume imaging (diameter < 50 mm), the polyvalent small FOV CBCT (2D and three-dimensional imaging) system used in this study could reach performances similar to those of the large FOV CBCT.

Pinhole SPECT imaging: compact projection/backprojection operator for efficient algebraic reconstruction.

We describe the efficient algebraic reconstruction (EAR) method, which applies to cone-beam tomographic reconstruction problems with a circular symmetry. Three independant steps/stages are presented, which use two symmetries and a factorization of the point spread functions (PSFs), each reducing computing times and eventually storage in memory or hard drive. In the case of pinhole single photon emission computed tomography (SPECT), we show how the EAR method can incorporate most of the physical and geometrical effects which change the PSF compared to the Dirac function assumed in analytical methods, thus showing improvements on reconstructed images. We also compare results obtained by the EAR method with a cubic grid implementation of an algebraic method and modeling of the PSF and we show that there is no significant loss of quality, despite the use of a noncubic grid for voxels in the EAR method. Data from a phantom, reconstructed with the EAR method, demonstrate 1.08-mm spatial tomographic resolution despite the use of a 1.5-mm pinhole SPECT device and several applications in rat and mouse imaging are shown. Finally, we discuss the conditions of application of the method when symmetries are broken, by considering the different parameters of the calibration and nonsymmetric physical effects such as attenuation.

Assessment of left ventricular perfusion, volumes, and motion in mice using pinhole gated SPECT.

UNLABELLED: Quantitative functional normal data should be a prerequisite before applying SPECT in murine models of cardiac disease. Therefore, we investigated the capability of in vivo pinhole gated SPECT for establishment of a reference database for left ventricular myocardial perfusion, volumes, and motion in normal mice. METHODS: A small-animal dedicated pinhole gamma-camera with a field of view of 17 cm and a focal distance of 12 cm was used with a 1.5-mm pinhole and a 2.5-cm radius of rotation. Phantoms were designed to test spatial resolution and microvolume measurements of accuracy. Eight adult normal mice (CD1) were studied using a heated mixture of air (0.3 L/min) and 1.5%-2.5% isoflurane for anesthesia. For myocardial perfusion, 350-450 MBq of (99m)Tc-tetrofosmin were used in 0.15-0.25 mL. Gated acquisitions (8 or 10 time bins per cardiac cycle) were obtained using a 180 degrees circular arc and 48 anterior projections of 300 R-R intervals. Image reconstruction was done using a specific Algebraic Reconstruction Technique (ART) cone-beam algorithm. For quantification, reconstructed images were processed using standard nuclear medicine software. RESULTS: Millimetric spatial resolution and volume calibration linear relationships (r(2) = 0.99) in the 10- to 100-muL range were obtained in phantoms and used to scale in vivo volume values. In mice, left ventricular perfusion was lower in the apex (65% +/- 6%) versus lateral (72% +/- 5%), inferior (74% +/- 5%), septum (75% +/- 4%), and anterior (74% +/- 2%) walls. The left ventricular ejection fraction was 60% +/- 9%, end-diastolic volume was 50 +/- 8 muL, end-systolic volume was 20 +/- 6 muL, stroke volume was 29.5 +/- 6 muL, and cardiac output was 9.6 +/- 1.6 mL/min. Wall thickening was higher in the apex (47% +/- 12%) versus lateral (30% +/- 9%), inferior (33% +/- 8%), septum (37% +/- 10%), and anterior (33% +/- 10%) walls. CONCLUSION: This work shows that in vivo pinhole gated SPECT can be used for assessment of left ventricular perfusion, volumes, and cardiac function in normal mice.

[Sentinel lymph node biopsy with micrometastases in breast cancer: histological data and surgical implications. About a series of 201 axillary dissections after peroperative sentinel node identification]. / Ganglions sentinelles avec micrométastases dans le cancer du sein: données histologiques et implications chirurgicales. A propos d'une série de 201 curages axillaires après identification peropératoire des ganglions sentinelles.

The benefit of systematic dissection of the non-sentinel lymph nodes (NSLN) in case of micrometastases (> or = 2 mm) in sentinel lymph nodes (SLN) is still being debated. The purpose of this work was to identify, from the histological characteristics of the micrometastases and the primitive tumors out of a series of 201 invasive breast carcinomas, of which 57.2% were pTl, which axillary dissection could be avoided. All cases had axillary dissection after peroperative SLN identification. The SLN were examined after fixation hy HE and immunohistochemical techniques (IHC), over their entire thickness from 2 to 3 mm-thick blocks of tissue and according to levels of histological sections with a spacing of 500 microm. The SLN were metastasized in 87/201 cases (43.3%) and in 29/8 7 cases (33.3%) it concerned micrometastases, 2/3 of which was only detected by IHC. The ability to discover micrometastases was proportional to the number of histological sections analyzed (58.6%, 82.7% and 100% of discovery with 1, 3 and 5 levels per block respectively). In 8/29 cases (27.6%) the NSLN were metastasized and in 6/8 cases it concerned macrometastases (> 2 mm). Taken separately, the characteristics of the tumors (size, histological type, grading, angioinvasion, multifocality), of the micrometastases (HE detection vs IHC detection, size, number) and of the site of injection of the radiotracer (peritumoral versus sub-areolar) did not allow us to isolate a group with micrometastases in the SLN but without metastases in the NSLN. However, the nine pT1 ductal carcinomas without angioinvasion were all NSLN negative. In conclusion, these results show that identification of micrometastases in SLN may influence the surgical decisions of re-excision, and that methodology of the pathological analysis is determinant.

Comparing respiratory gated with delayed scans in the detection of colorectal carcinoma hepatic and pulmonary metastases with 18F-FDG PET-CT.

PURPOSE: In patients experiencing colorectal carcinoma, exhaustive analysis of indicates extent of hepatic and pulmonary surgery that prolongs survival of patients. PATIENTS AND METHODS: To localize metastasis, we compared 2 F-FDG PET-CT imaging protocols, early respiratory gated scan, and delayed scan, to standard PET imaging procedure. SUVmax and lesion-to-healthy tissue ratio were measured in 60 pulmonary and 21 hepatic lesions by each of the 2 imaging protocols. RESULTS: In the liver, metastatic lesion-to-healthy tissue ratios significantly increased on delayed scans as compared with early scans (P < 0.001). Better ratios could not be obtained when using respiratory gated scans, whereas more lesions were detected on delayed scans. In the lungs, metastatic lesion- to-healthy tissue ratio increased significantly on delayed scans for largest lesions (P < 0.001). Ratios were not better when exploring smallest metastatic lesions or when using respiratory gated scans. Factors interfering with F-FDG PET-CT sensitivity are discussed, such as respiratory motion and high FDG physiological uptake in healthy liver parenchyma. CONCLUSIONS: Our studies indicate that routine acquisitions should use delayed hepatic scans for all patients referred for evaluation, recurrence check, or monitoring of colorectal adenocarcinoma. Delayed pulmonary scans are useful for the largest metastatic lesions and should be used in addition to early scan. In our experience, respiratory gated scans seem to be less convenient because of a low sensitivity in detection, as compared with the delayed technique; in addition, this technique is currently complicated by some technical issues, although these might be overcome with new gated protocols.

Dual-isotope 99mTc-MIBI/123I parathyroid scintigraphy in primary hyperparathyroidism: comparison of subtraction SPECT/CT and pinhole planar scan.

PURPOSE: In patients with primary hyperparathyroidism, the preoperative imaging objective is to locate accurately and reliably uniglandular or multiglandular hyperfunctioning parathyroid, to guide surgery, particularly for minimally invasive method. Subtraction planar scintigraphy with dual-isotope (I/Tc-MIBI) is an efficient examination to specify abnormal parathyroid location, but without accurate anatomic reference. This lack should be avoided by a hybrid SPECT/CT image acquisition. METHODS: We compared planar scans (neck and mediastinum parallel-hole, associated with anterior neck pinhole) to neck and mediastinum SPECT/CT, all with subtraction (I/Tc-MIBI) method, in exact location of abnormal parathyroid in 50 patients with sporadic primary hyperparathyroidism. Surgical and histological findings were used as the standard of comparison. RESULTS: Sensitivity is equivalent for the 2 protocols (86% and 75% for SPECT/CT and planar protocol, respectively, P = 0.15), but SPECT/CT was highly specific (specificity 100% and 90% for SPECT/CT and planar protocol, respectively, P = 0.04). In patients with concomitant thyroid disease, subtraction SPECT/CT appeared to be more sensitive than planar protocol (88% and 62% for SPECT/CT and planar protocol, respectively, P = 0.04). CONCLUSIONS: In preoperative assessment of primary hyperparathyroidism and to guide surgery, we propose to perform first subtraction SPECT/CT and to complete it with neck pinhole, only if tomoscintigraphy is negative.

RSK2 is a modulator of craniofacial development.

BACKGROUND: The RSK2 gene is responsible for Coffin-Lowry syndrome, an X-linked dominant genetic disorder causing mental retardation, skeletal growth delays, with craniofacial and digital abnormalities typically associated with this syndrome. Craniofacial and dental anomalies encountered in this rare disease have been poorly characterized. METHODOLOGY/PRINCIPAL FINDINGS: We examined, using X-Ray microtomographic analysis, the variable craniofacial dysmorphism and dental anomalies present in Rsk2 knockout mice, a model of Coffin-Lowry syndrome, as well as in triple Rsk1,2,3 knockout mutants. We report Rsk mutation produces surpernumerary teeth midline/mesial to the first molar. This highly penetrant phenotype recapitulates more ancestral tooth structures lost with evolution. Most likely this leads to a reduction of the maxillary diastema. Abnormalities of molar shape were generally restricted to the mesial part of both upper and lower first molars (M1). Expression analysis of the four Rsk genes (Rsk1, 2, 3 and 4) was performed at various stages of odontogenesis in wild-type (WT) mice. Rsk2 is expressed in the mesenchymal, neural crest-derived compartment, correlating with proliferative areas of the developing teeth. This is consistent with RSK2 functioning in cell cycle control and growth regulation, functions potentially responsible for severe dental phenotypes. To uncover molecular pathways involved in the etiology of these defects, we performed a comparative transcriptomic (DNA microarray) analysis of mandibular wild-type versus Rsk2-/Y molars. We further demonstrated a misregulation of several critical genes, using a Rsk2 shRNA knock-down strategy in molar tooth germs cultured in vitro. CONCLUSIONS: This study reveals RSK2 regulates craniofacial development including tooth development and patterning via novel transcriptional targets.