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.

Radiological sinus lift: a new minimally invasive CT-guided procedure for maxillary sinus floor elevation in implant dentistry.

PURPOSE: Implant therapy has become an excellent treatment modality as its inception into the modern era of dentistry. However, when patients present with advanced atrophy of the maxillary alveolar ridge, the procedure of choice to restore the anatomic bone deficiency is surgical maxillary sinus floor elevation or sinus lift. The purpose of this study was to describe the CT guided sinus lift technique and to illustrate the minimally invasive aspect of this new radiological procedure called radiological sinus lift. MATERIAL AND METHODS: For this prospective study, 17 cadaver heads which met our inclusion criteria (edentulous posterior maxillary sector and bone height less than 5 mm) were analyzed using cone beam computed tomography (CBCT) and orthopantomography (OPT). CT and sinus endoscopy was used to guide each step in the procedure. The radiological sinus lift technique consists of the following four stages: Approach. A 14.5 G OstyCut needle was inserted mesial to the canine eminence, and manual drilling was performed parallel to the sinus floor. Osteotomy. An inner obturator with a blunt tip was introduced to compress bone, to push it in close proximity to the sinus membrane and finally to create an osseous window opening into the submucosal space. Lifting. The sinus lift was performed using hydrodissection with dilute iodinated contrast medium. Filling. The submucosal space was then filled with an injection of dilute collagen. Success of the radiological sinus lift procedure was defined by the presence of a dome shape visible within the maxillary alveolar recess. All cases were imaged postoperatively using OPT and maxillary CBCT. RESULTS: Twelve maxillary sinuses underwent the radiological sinus floor elevation procedure. A dome shape of the Schneiderian membrane was achieved in eight maxillary sinuses (66.7%). All failures (n = 4) were caused by mucosal perforation at the time of maxillary sinus osteotomy. Mean height of membrane elevation was 12.0 mm, with a mean intervention time of 45 min. CONCLUSION: This experimental study evaluates a new minimally radiological procedure for maxillary sinus floor elevation, which provides an interventional radiological alternative to the classical surgical lateral approach and achieves an equivalent success rate to that cited in the literature for the surgical approach, a low morbidity and a shorter operating time.

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.

Intense 18F-choline uptake after minor head injury: misleading PET/CT result in a patient with biochemical relapse of prostate adenocarcinoma.

We report the results of whole body 18F-fluorocholine (FCH) PET/CT in a single patient with biochemical suspicion of prostate adenocarcinoma relapse and recent history of minor head injury. PET showed an intense area of increased FCH uptake in the right parietal bone, without any morphological abnormality on either CT or skull radiographs. Understanding the radiotracer's physiological biodistribution as well as the nonmalignant etiologies of FCH uptake are essential requirements for a correct diagnostic interpretation of FCH PET/CT in patients with biological recurrence of prostate cancer.

EBV limbic encephalitis after allogenic hematopoietic stem cell transplantation.

The clinical and radiological presentations of Epstein-Barr virus (EBV) encephalitis are pleomorphic, but a common and characteristic finding is an increased T2-weighted signal in the bilateral thalami and basal ganglia. We report here a case of post-transplant acute limbic encephalitis (PALE) syndrome that was possibly related to EBV infection. Six weeks after hematopoietic stem-cell transplantation, the patient developed confusion and anterograde amnesia. Brain magnetic resonance imaging (MRI) was performed and revealed bi-hippocampal and amygdala signal abnormalities. The technetium-99m single-photon emission computed tomography ((99m)Tc SPECT) imaging confirmed bilateral limbic structural involvement. The clinical, biological and radiological presentations were consistent with a diagnosis of EBV-induced PALE syndrome. To our knowledge, this is the first described case of PALE syndrome possibly related to EBV infection.