Three-phase bone scintigraphy of hydroxyapatite ocular implants

Hydroxyapatite ocular implants are replicas of lamellar bone tissue derived from the exoskeleton of a reef-building coral by a hydrothermal chemical exchange reaction. Attached to the eye muscles, they act as a passive framework for fibrovascular ingrowth and can be drilled to hold the visible part of the artificial eye and allow synchronous eye movement. Fibrovascular ingrowth has to be confirmed by bone scintigraphy before the drilling procedure. This study monitored the vascular ingrowth into the implant in ten patients over 12 months to establish a clinically feasible imaging protocol. Tracer accumulation was monitored visually and quantitatively in dynamic and single-photon emission tomography (SPET) scans after the intravenous administration of 600 MBq of^99mTc-DPD. The implants showed no tracer accumulation in the arterial or blood pool phase. Accordingly, dynamic scintigraphy can be omitted from the imaging protocol. Delayed tracer accumulation appeared no earlier than 2 and no later than 6 months after surgery. Planar scintigraphy is not recommended as high-resolution SPET is necessary to separate the implant from the surrounding bone. We conclude that imaging can be confined to high-resolution SPET 3 h after tracer injection, no earlier than 3 months after surgery. The vascularized hydroxyapatite orbital implant is an important in vivo model for bone-seeking agents to study their uptake kinetics independently of any soft tissue and bone disease. Our results provide evidence that in normal bones the chemical adsorption of^99mTc-DPD into the crystalline structure of hydroxyapatite is the only quantitatively relevant uptake mechanism.     

Vascularisation of ocular coralline hydroxyapatite implants

Vascularisation of coralline hydroxyapatite used to replace the enucleated bulb is of critical importance for the uncomplicated implantation of a motility peg connecting the implant with the cosmetic prosthesis. Technetium-99m diphosphopropanedicarboxylic acid (DPD) single-photon emission tomography (SPET) was used to evaluate the rate of vascularisation as well as the time required for completion of vascularisation. Twenty-four patients were enrolled in the study, which was designed to evaluate vascularisation 10 days, 2 months and 4 months after implantation of a coralline implant. Nineteen patients completed the study and the visual impression of the completion of the vascularisation was scored from 0 (no vascularisation) to ++++ (complete vascularisation) for each patient. No tracer accumulation was detected in any patient at the 10-day examination. Increasing vascularisation was demonstrated with time, and full vascularisation of the coralline implant was seen in all but one case by 4 months after implantation. We conclude that vascularisation of ocular coralline hydroxyapatite implants occurs early and is completed by 4 months after implantation in most cases, but should be confirmed at this time by^99mTc-DPD SPET.     

Evaluation of vascularization of coralline hydroxyapatite ocular implants by magnetic resonance imaging

A coralline hydroxyapatite orbital implant may be placed after ocular enucleation or evisceration. It must be vascularized to support epithelialization of a hole drilled in its anterior face for insertion of a motility peg. We used gadolinium-DTPA enhanced magnetic resonance imaging (MRI) of the orbits of two patients to assess fibrovascular penetration into their implants. MRI provides a reliable determination of implant vascularization and greater anatomic detail than 99m technetium-MDP bone scanning.     

99Tcm-MDP全身骨显像、99Tcm-MDP SPECT-CT和18F-FDG SPECT-CT探测脊柱转移瘤的比较

目的 比较99Tcm-亚甲基二膦酸盐(99Tcm-MDP)全身骨显像、99Fcm-MDPSPECT-CT与18F-FDG SPECT-CT诊断脊柱转移瘤的临床价值.方法 对行常规99Tcm-MDP全身骨显像的88例肿瘤患者同时行99Tcm-MDP SPECT-CT,同期(2周内)行18F-FDG SPECT-CT.回顾...     

Different fibrovascularization rate between coralline hydroxyapatite and high density porous polyethylene (Medpore) measured by 99mTc-MDP bone scintigraphy 6 months after intraorbital implantation

Many materials and types of implant have been used to achieve a cosmetic effect and prosthesis motility in the anophthalmic socket. Hydroxyapatite remains the implant material of choice for producing the most natural prosthesis motility while porous polyethylene shows promising characteristics as another useful material. The aim of this study was to compare the fibrovascular ingrowth rates of orbital implants between coralline hydroxyapatite and high density porous polyethylene (Medpore). The fibrovascularization rate is determined by bone imaging using 99mTc methylene diphosphonate (99mTc-MDP) 6 months after implantation. Our study included 29 patients with coralline, and nine patients with Medpore implants. Our results showed that groups with coralline implants appearing to achieve complete fibrovascularization at a much more rapid rate than those with Medpore. The differences in rate were statistically significant.     

Findings of hepatopulmonary syndrome on breath-hold perfusion SPECT-CT fusion images

Pulmonary perfusion SPECT-CT fusion images were used to characterize CT manifestations of intrapulmonary arteriovenous communications (AVC) causing right-to-left shunt and hepatopulmonary syndrome (HPS). After scanning the whole body and obtaining multiple view images of the lung, deep-inspiratory breath-hold (DIBrH) SPECT was obtained in 2 patients with HPS, which was automatically and three-dimensionally co-registered with DIBrH CT. In both patients, the whole body scan depicted systemic organs and confirmed the existence of right-to-left shunt. DIBrH SPECT-CT fusion images showed that perfusion defects were predominantly located at subpleural reticulo-nodular opacities and/or dilated vessels in the lung base. Subpleural reticulo-nodular opacities and/or dilated vessels in the lung base appear to be characteristic CT manifestation of intrapulmonary AVC in HPS.     

Computer-aided detection of bone metastasis in bone scintigraphy images using parallelepiped classification method

Annals of Nuclear Medicine - Accurate diagnosis of metastatic tissue on bone scintigraphy images is of paramount importance in making treatment decisions. Although several automated systems have...     

甲状腺肿瘤SPECT-CT融合显像的应用近况

甲状腺肿瘤SPECT-CT融合显像将解剖成像与功能成像的优势相结合,克服了以往SPECT、CT单一成像的各自缺陷,可同时提供病变的解剖结构与功能代谢信息,能在术前对甲状腺肿瘤进行精确定位,在鉴别肿瘤良恶性、探测复发或转移、评价治疗效果等方面具有独特优势。与PET-CT相比,其价格低廉,具有较高的临床应用价值。     

Super-superscan on a bone scintigraphy

Superscans on bone scintigraphy have been described mostly in metastatic and metabolic bone diseases, with different patterns and appearances of radiotracer uptake. This is a report of bone scintigraphy demonstrating superimposed metastatic and metabolic superscan in a patient with prostate cancer, who subsequently developed renal osteodystrophy. Two years after the first bone scintigraphy showing multiple metastases, the patient developed renal insufficiency, hyperphosphoremia, and hypocalcemia. Repeat bone scintigraphy demonstrates significantly different appearance from that of the first study. Caution should be exercised when interpreting a bone scintigraphy in patients with known malignancy and coexisting renal failure or metabolic bone disease. Superimposed appearances of metastatic and metabolic superscan may obscure recognition of osseous metastases.     

Utility of 99mTc-MDP hybrid SPECT-CT for diagnosis of skull base osteomyelitis: comparison with planar bone scintigraphy, SPECT, and CT

Purpose

To evaluate single photon emission tomography–computed tomography (SPECT-CT) for diagnosis of skull base osteomyelitis (SBO) and to compare this technique with planar bone scintigraphy (BS), SPECT, and CT.

Methods

Data from 13 patients with known/suspected SBO were retrospectively analysed. Planar BS and SPECT images were evaluated by an experienced nuclear medicine physician, CT by and experienced radiologist, and SPECT-CT by the nuclear medicine physician and radiologist in consensus. On the basis of diagnostic confidence a score of 1–5 was given, with 1 being definitely osteomyelitis, 2 being probably osteomyelitis, 3 being equivocal, 4 being probably normal, and 5 being definitely normal. ROC analysis areas under the curves (AUC) were calculated. For diagnostic values a score of ≤2 was taken as positive. Clinical/imaging follow-up/microbiology was taken as reference standard.

Results

AUC was largest for SPECT-CT (0.977) followed by SPECT (0.909), CT (0.886), and planar BS (0.614). However, no significant difference was found between the techniques except for borderline significance between planar BS with SPECT-CT (P = 0.071) and CT (P = 0.072). Accuracy was 46 % for planar BS, 85 % for SPECT, 77 % for CT and 92 % for SPECT-CT.

Conclusion

SPECT-CT seems to be useful, but not superior to planar BS, SPECT, or CT, for diagnosis of SBO.     

Persistent sternum synchondroses on bone scintigraphy

This report describes the case history of two patients who showed a hyperactive midsternal area on bone scintigraphy due to a persistent sternal synchondrosis. Whereas this anatomical variant is diagnosed infrequently, midsternal hotspots can sometimes be related to arthrotic degeneration of these extra joint spaces. In the differential diagnosis of midsternal hotspots on bone scintigraphy, persistent sternum synchondroses should be considered.     

Persistent sternum synchondroses on bone scintigraphy

This report describes the case history of two patients who showed a hyperactive midsternal area on bone scintigraphy due to a persistent sternal synchondrosis. Whereas this anatomical variant is diagnosed infrequently, midsternal hotspots can sometimes be related to arthrotic degeneration of these extra joint spaces. In the differential diagnosis of midsternal hotspots on bone scintigraphy, persistent sternum synchondroses should be considered.