Incidental non-secreting adrenal masses in cancer patients: intra-individual comparison of 18F-fluorodeoxyglucose positron emission tomography/computed tomography with computed tomography and shift magnetic resonance imaging.

The ability of integrated (18)F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) to distinguish between benign and malignant incidental non-secreting adrenal masses was evaluated in cancer patients. Results were compared with those of CT and shift magnetic resonance imaging (MRI). A total of 1832 cancer patients who had undergone FDG PET/CT scans were retrospectively evaluated. Visual interpretation, tumour maximum standardized uptake value (SUV(max)), liver SUV(max) and tumour/liver SUV(max) ratios were correlated with the findings of CT, shift MRI and final diagnosis (based on biopsy or clinical/radiological follow-up). A total of 109 adrenal masses were found: 49 were malignant and 60 were benign on final diagnosis. A tumour/liver SUV(max) ratio threshold of 1.0 was more accurate in differentiating the tumour type than tumour SUV(max) or visual interpretation alone. Diagnostic accuracy of CT and shift MRI (92 - 97%) was similar to that for FDG PET/CT (94 - 97%). In conclusion, FDG PET/CT accurately characterizes adrenal tumours, with excellent sensitivity and specificity. Use of 1.0 as the threshold for the tumour/liver SUV(max) ratio seems to be promising for distinguishing benign from malignant adrenal masses in cancer patients.

[Diagnosis of fever of unknown origin (FUO). Positron emission tomography/computed tomography (PET-CT)]. / Diagnostik bei Fieber unklarer Genese (FUO) - Positronen-Emissions-Tomographie/Computertomographie(PET-CT).

Nuclear medicine imaging is now well accepted for the localization of septic foci. But in patients the results of infection scintigraphy, radiology and ultrasound remain unsatisfactory in the diagnosis of fever of unknown origin (FUO). In contrast to septic infections, patients with FUO - mostly in elderly patients - tend to have such conditions as occult tumours, atypical pneumonia, hematoblastosis, malignant lymphomas. (18)F(Fluor-18)-Fluordeoxyglucose-PET ((18)F-FDG PET) has made it possible to localize symptomatically occult changes with a high diagnostic accuracy and to achieve differentiation between benign and malignant changes.

(99m)Tc-Fab' fragments (sulesomab) for imaging septically loosened total knee arthroplasty.

The diagnostic accuracy of infection scintigraphy with (99m)Tc-labelled monoclonal antibody Fab' fragments (sulesomab) was studied in patients with suspected total knee arthroplasty (TKA) infection. Images from 26 patients were evaluated by two independent readers and compared with a quantitative interpretation of time-activity courses. Microbiological examinations and joint aspiration results were used as reference standards. Histologically, aseptic TKA loosening occurred in two patients and severe, moderate or mild septic loosening in four, nine and 11 patients, respectively. Diagnostic accuracy for severe infection was 100% for both readers, whereas for moderate infection accuracy decreased by 12% and 12% for readers one and two, respectively. For mild infection a further decrease of approximately 61% and 52% occurred for readers one and two, respectively. Quantitative evaluation gave significantly better results over visual interpretation with a diagnostic accuracy of 100% for severe infection and decreased by only 10% and 15% in patients with moderate and mild infection, respectively. Quantitative evaluation of (99m)Tc-Fab' fragments is highly sensitive and specific for diagnostic imaging of infection in patients with septically-loosened TKA.

[Nuclear medical imaging in case of painful knee arthroplasty]. / Nuklearmedizinische Diagnostik bei schmerzhafter Knieprothese.

RATIONALE: The aim of the present study was to calculate the overall diagnostic accuracy of nuclear medical imaging in patients with painful knee arthroplasty. MATERIAL AND METHODS: This retrospective study of all patients (n=87) where a (99m)Tc-triple phase bone scintigraphy (TPBS; n=120) and (99m)Tc-anti-granulocyte scintigraphy (BW 250/183; n=20) for a painful knee arthroplasty was performed between 2003 and 2007. RESULTS: A total of 87 patients with 94 knee arthroplasties were examined to detect septic and aseptic loosening and to differentiate between them. The sensitivity, specificity, the positive and negative predictive value and accuracy of TPBS for the detection of septic knee arthroplasty loosening was 100%, 85%, 55%, 100%, 73% and for BW 250/183 was 91%, 66%, 76%, 85%, 80% for sepsis, respectively. A significant increase in diagnostic accuracy with 94%, 88%, 89%, 95% und 89% (p <0.001) could be achieved when both methods were used in combination. CONCLUSION: Both methods alone have high negative predictive values, but the combination of both is complementary and significantly increases the diagnostic accuracy and positive predictive value for final diagnosis of knee arthroplasty loosening.

Quantitative [(123)I]FP-CIT pinhole SPECT imaging predicts striatal dopamine levels, but not number of nigral neurons in different mouse models of Parkinson's disease.

Single photon emission computed tomography (SPECT) using [(123)I]FP-CIT as radioligand for the dopamine transporter has become a widely used tool to monitor the integrity of the nigrostriatal dopaminergic projection in Parkinson's disease (PD). Previous studies with pinhole SPECT in small animals have demonstrated that the striatal [(123)I]FP-CIT binding indeed correlates with the striatal dopamine transporter protein level. It is unclear, however, if there is a stable relationship between the striatal [(123)I]FP-CIT binding and other functionally important parameters of the nigrostriatal system, such as the striatal dopamine levels and the number of dopaminergic neurons in the substantia nigra. To assess this question experimentally, we studied two different mouse models of PD, namely a mild 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxication paradigm, to model mild nigrostriatal damage and the intrastriatal 6-hydroxydopamine paradigm to model more advanced nigrostriatal damage. Our data demonstrate that the striatal [(123)I]FP-CIT binding measured by SPECT in vivo precisely predicts the striatal dopamine concentrations, but does not necessarily correlate with the nigral dopaminergic cell number. Thus, the present work underscores that FP-CIT SPECT does only allow judging the integrity of the striatal dopaminergic nerve terminals, but not the nigral dopaminergic cells in PD. This finding may have significant impact on the use of [(123)I]FP-CIT SPECT as a surrogate marker for clinical trials aimed at measuring neuroprotection.

Scintigraphy with 99mTc-labeled heat-altered erythrocytes in diagnosing hyposplenia: prospective comparison to 99mTc-labeled colloids and colour-coded duplex ultrasonography.

AIM: Ultrasound may be a cheap alternative to scintigraphic determination of splenic function. We directly compared nanocolloid scintigraphy (NS), scintigraphy with heat-altered erythrocytes (ES), and colour-coded Doppler sonography (DS) in patients with chronic inflammatory bowel disease (CIBD). PATIENTS, METHODS: 35 patients were included into the study. Clearance rates were determined in ES, spleen/liver ratios (SLR) were measured scintigraphically in ES/NS. In DS, spleen size, echogenicity, and vascular resistance indices (RI) were determined. The results were compared to each other, to the clinical activity scores for CIBD, and to the course of the disease. RESULTS: Based on the blood erythrocyte clearance serving as standard, patients had a good (19 patients), impaired (5), or missing splenic function (11). There was a good correlation of the clearance to SLR in ES (0.63, p < 0.01). The 10 min / 45 min ES clearance showed a high correlation (Spearman-Rho 0.87, p < 0.01). The SLR in ES at 2, 5, 10 and 45 min also correlated well with each other (Spearman-Rho > 0.9, p < 0.01; SLR > 3.45 normal splenic function, SLR < 1.22 indicated hyposplenia). There were no correlations between the results of NS, DS, Howell-Jolly-bodies, or clinical parameters. Only ES and the erythrocyte clearance correlated well. Howell-Jolly-Bodies detected 1 of 11 patients with hyposplenia while false-positive in 4. CONCLUSION: Ultrasound and colloid scintigraphy show a low correlation with clearance of heat-altered erythrocytes. Only ES shows a good correlation in patients with CIBD. The clearance at 10 min already reliably determines splenic function. SLR may be determined after 10 minutes and is predictive of normal function if above 3.45 while SLR < 1.2 indicated hyposplenia.

What is the best pre-therapeutic dosimetry for successful radioiodine therapy of multifocal autonomy?

PURPOSE: Dose calculation for radioiodine therapy (RIT) of multifocal autonomies (MFA) is a problem as therapeutic outcome may be worse than in other kinds of autonomies. We compared different dosimetric concepts in our patients. PATIENTS, METHODS: Data from 187 patients who had undergone RIT for MFA (Marinelli algorithm, volumetric compromise) were included in the study. For calculation, either a standard or a measured half-life had been used and the dosimetric compromise (150 Gy, total thyroid volume). Therapeutic activities were calculated by 2 alternative concepts and compared to therapeutic success achieved (concept of TcTUs-based calculation of autonomous volume with 300 Gy and TcTUs-based adaptation of target dose on total thyroid volume). RESULTS: If a standard half-life is used, therapeutic success was achieved in 90.2% (hypothyroidism 23,1%, n = 143). If a measured half-life was used the success rate was 93.1% (13,6% hypothyroidism, n = 44). These differences were statistically not significant, neither for all patients together nor for subgroups eu-, hypo-, or hyperthyroid after therapy (ANOVA, all p > 0.05). The alternative dosimetric concepts would have resulted either in significantly lower organ doses (TcTUs-based calculation of autonomous volume; 80.76 +/- 80.6 Gy versus 125.6 +/- 46.3 Gy; p < 0.0001) or in systematic over-treatment with significantly higher doses (TcTUs-adapted concept; 164.2 +/- 101.7 Gy versus 125.6 +/- 46.3 Gy; p = 0.0097). CONCLUSIONS: TcTUsbased determination of the autonomous volume should not be performed, the TcTUs-based adaptation of the target dose will only increase the rate of hypothyroidism. A standard half-life may be used in pre-therapeutic dosimetry for RIT of MFA. If so, individual therapeutic activities may be calculated based on thyroid size corrected to the 24h ITUs without using Marinelli's algorithm.

Decrease of (99m)Tc-uptake in autonomous thyroid tissue in Germany since the 1970s. Clinical implications for radioiodine therapy.

AIM: The clinical relevance of thyroidal autonomy, i.e. the risk of a patient to become hyperthyroid after exposure to iodine, can be estimated by measurement of the thyroidal (99m)Tc uptake under suppression of TSH (TcTUs). The upper tolerable limit has been set to 2% some 25 years ago. Considering the increase in nutritional iodine uptake over the last 15 years, we wanted to find out if the TcTUs per ml of autonomous volume may have changed. PATIENTS, METHODS: We performed a pilot study in 1166 randomly chosen patients from 1980-2003 with different kinds of benign thyroid disorders to determine changes in TcTU or TcTUs over time. A second analysis was performed in 1063 patients from 1987-2004 with unifocal autonomy (UFA). In these patients, the volume of the autonomous tissue can be determined precisely thus allowing for exact determination of TcTUs per ml of autonomous volume. RESULTS: The pilot study demonstrated that the TcTUs or the TcTU has been falling over the last 25 years in all benign thyroid disorders (p < 0.01). The total thyroid volume has also been decreasing in all disorders. In the second analysis of UFA only, 500 from the 1063 patients fulfilled the inclusion criteria. In these patients, the TcTUs per ml of autonomous volume has fallen from an average of 0.48% to an average of 0.28%. These results are statistically significant as determined by ANOVA testing (p = 0.032). CONCLUSION: As the TcTUs in relation to autonomous volume has dropped by approximately 40% over the last 25 years, the upper limit for a normal TcTUs should be reduced to 1-1.4%, dependent on regional factors.

Combination of 'idiopathic' REM sleep behaviour disorder and olfactory dysfunction as possible indicator for alpha-synucleinopathy demonstrated by dopamine transporter FP-CIT-SPECT.

REM sleep behaviour disorder (RBD) and olfactory dysfunction are common and very early features of alpha-synucleinopathies, in particular Parkinson's disease. To investigate the hypothesis that these two clinical features in combination are an indicator of evolving alpha-synucleinopathy, olfactory function was assessed in RBD. We studied 30 patients (18 male, 12 female; mean age 48 +/- 14 years, range 19-78 years) with clinical (idiopathic, n = 6; symptomatic, n = 13, mostly associated with narcolepsy) or subclinical (n = 11, associated with narcolepsy) RBD according to standard criteria and 30 age- and gender-matched healthy control subjects using standardized 'Sniffin' Sticks'. RBD patients had a significantly higher olfactory threshold (P = 0.0001), lower discrimination score (P = 0.003), and lower identification score (P = 0.001). Compared with normative data, 97% of the RBD patients had a pathologically increased olfactory threshold, 63% an impaired odour discrimination score, and 63% a decreased identification score. On neurological examination, signs of parkinsonism were newly found in five patients with clinical RBD (not associated with narcolepsy), who usually had a long history of 'idiopathic' RBD. Four of the five patients fulfilled the UK Brain Bank criteria for the clinical diagnosis of Parkinson's disease. The underlying nigrostriatal degeneration of clinical Parkinson's disease was confirmed by I-123-FP-CIT SPECT in one patient and early nigrostriatal degeneration was identified by SPECT in a further two patients with 'idiopathic' clinical RBD out of 11 RBD patients who agreed to undergo SPECT studies. Our study shows that RBD patients have a profound impairment of olfactory function. Five patients with clinical RBD not associated with narcolepsy had clinical or imaging signs of nigrostriatal degeneration. This new clinical finding correlates with the neuropathological staging of Parkinson's disease (stages 1-3) as proposed by Braak. In stage 1, the anterior olfactory nucleus or the olfactory bulb is affected (along with the dorsal motor nucleus of the glossopharyngeal and vagal nerves). In stage 2, additional lesions consistently remain confined to the medulla oblongata and pontine tegmentum, which are critical areas for RBD. Midbrain lesions are found only in stage 3, in particular degeneration of dopaminergic neurons in the substantia nigra pars compacta. Thus, 'idiopathic' RBD patients with olfactory impairment might present with stage 2 preclinical alpha-synucleinopathy. Since narcoleptic patients are not known to have an increased risk of developing parkinsonism, the pathophysiology and clinical relevance of hyposmia in RBD/narcolepsy patients requires further research.

Development and clinical application of peptide-based radiopharmaceuticals.

Peptide-based radiopharmaceuticals have been introduced into clinical work more than a decade ago. The first and most successful imaging agent to date is the somatostatin analog octreotide. It is used for somatostatin receptor scintigraphy and also receptor-mediated peptide-radiotherapy of neuroendocrine tumors. For in vivo use as radiopharmaceutical, the natural peptide is modified in order to enhance the metabolic stability and to allow stable labeling with a so-called residualizing label. This means, that a radiometal chelator complex bound to a modified peptide stable in serum is internalized into the target cells via a specific receptor. The peptide then undergoes lysosomal degradation leaving the radiometal-chelator complex trapped inside the cell, leading to a high target to background ratio. The successful development of new radiopeptides is thus dependent on modifications of a given natural peptide while preserving the binding affinity for the target receptor(s) at the same time. Other peptides than somatostatin are under development for use as radiopeptides such as Minigastrin, GLP-1, VIP, Substance P, or Neurotensin. Some show very favorable results in clinical trials, like Minigastrin for example. Furthermore, there is increasing interest in peptide-binding sites other than the "classical" receptors for regulatory peptides specifically over-expressed by (neuroendocrine) tumors. In this paper, we provide an overview of the biochemical and radiochemical aspects of radiopeptide development, the current state of clinical use of radiopeptides for diagnosis and therapy of tumors, the current state of development of new compounds, and future developments.

99mTc-labeling and in vitro and in vivo evaluation of HYNIC- and (Nalpha-His)acetic acid-modified [D-Glu1]-minigastrin.

Gastrin/CCK-2 receptors are overexpressed in a number of tumors such as medullary thyroid cancer (MTC) and small cell lung cancer (SCLC). Recently [D-Glu1]-minigastrin (MG) has been radiolabeled with 131I, 111In, and 90Y and evaluated in patients. This study describes the labeling and evaluation of MG with technetium-99m using two different labeling approaches: HYNIC as bifunctional coupling agent and (Nalpha-His)Ac as tridentate ligand for 99mTc(CO3) labeling. Labeling was perfomed at high specific activities using Tricine and EDDA as coligands for HYNIC-MG and [99mTc(OH2)3(CO)3]+ for (Nalpha-His)Ac-MG. Stability experiments were carried out by reversed phase HPLC analysis in PBS, serum, histidine, and cysteine solutions, as well as rat liver and kidney homogenates. Receptor binding and internalization experiments were performed using CCK-2 receptor positive AR42J rat pancreatic tumor cells. Biodistribution experiments were carried out in nude mice carrying AR42J tumors by injection of 99mTc-labeled peptide with or without coinjection of 50 microg of minigastrin I human (MGh). HYNIC-MG and (Nalpha-His)Ac-MG could be radiolabeled at high specific activities (>1 Ci/micromol). For HYNIC-MG, high labeling yields (>95%) were achieved using Tricine and EDDA as coligands. Stability experiments of all 99mTc-labeled conjugates revealed a high stability of the label in PBS and serum as well as toward challenge with histidine and cysteine. Incubation in kidney homogenates resulted in a rapid degradation of all conjugates with <10% intact peptide after 60 min at 37 degrees C, with no considerable differences between the radiolabeled conjugates; a somewhat lower degradation rate was seen in liver homogenates. Protein binding varied considerably with lowest levels for 99mTc-EDDA/HYNIC-MG. Competition experiments of unlabeled conjugates on AR42J membranes versus [125I-Tyr12]-gastrin I showed high CCK-2 receptor affinity for all conjugates under study. Internalization behavior was very rapid for all radiolabeled conjugates in the order of 99mTc-(Nalpha-His)Ac-MG > 99mTc-EDDA/HYNIC-MG > 99mTc-Tricine/HYNIC-MG. In tumor-bearing nude mice the highest tumor-uptake was observed with 99mTc-EDDA/HYNIC-MG (8.1%ID/g) followed by 99mTc-Tricine/HYNIC-MG (2.2%ID/g) and 99mTc-(Nalpha-His)Ac-MG (1.2%ID/g) which correlated with kidney uptake (101.0%ID/g, 53.8%ID/g, 1.8%ID/g respectively). In this series of compounds 99mTc-EDDA/HYNIC-MG with its very high tumor/organ ratios except for kidneys seems to be the most promising agent to target CCK-2 receptors. Despite promising properties concerning receptor binding, internalization, and in vitro stability, 99mTc-(Nalpha-His)Ac-MG showed low tumor uptake in vivo.

Case report: drug interference with MIBG uptake in a patient with metastatic paraganglioma.

Metaiodobenzylguanidine (MIBG) labelled with iodine-131 ((131)I) has become a well established therapeutic tool for inoperable metastastic tumours of paraganglioma. There are different pharmacological substances known to interfere with MIBG-uptake which may result in a false negative MIBG scan. We present the case of a 26-year-old male polytoxicomanic patient with metastatic paraganglioma, who underwent MIBG therapy. During earlier therapies, MIBG uptake in the metastatic lesions was very high. A post-therapeutic whole-body scan subsequent to recent (131)I-MIBG therapy failed to detect the vast majority of metastatic lesions-except for two. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) showed metastases with a similar distribution to the initial MIBG scan. The possible reasons for the discrepancy in the findings of the MIBG scans and the (18)F-FDG-PET scan are discussed with special emphasis on drug intake prior to MIBG administration, increased MIBG turn-over and unknown drug mixture interference with MIBG uptake.

LeukoScan for imaging infection in different clinical settings: a retrospective evaluation and extended review of the literature.

PURPOSE: The aim of the current study was to determine the overall diagnostic accuracy of Tc-99m-labeled antigranulocyte monoclonal antibody Fab' fragments (LeukoScan) for the routine detection of bone and soft tissue infections in a retrospective evaluation. PATIENTS AND METHODS: 138 patients (63 men, 75 women; mean age, 58.29 +/- 25.38 years) with fever of unknown origin and possible endocarditis (n = 59), infection of arthroplastic joints (n = 20), arthritis (n = 16), peripheral (n = 15) and central bone infections (n = 14), soft tissue infection (n = 6), appendicitis (n = 4), pericarditis (n = 2), or vascular graft infection (n = 2) underwent imaging after injection of 555 to 925 MBq (15 to 25 mCi) Tc-99m-labeled antigranulocyte monoclonal antibody Fab' fragments (LeukoScan). RESULTS: True-positive results were found in 63 of 81 lesions. The overall sensitivity and specificity were 76% and 84%, respectively. In arthritis, seven of seven foci could be detected, whereas false-negative results were found in infections of the femoral bone in three of nine lesions and in periprosthetic infections of long bones in three of eight lesions. Good results were found in five of six soft-tissue infections, in four of six patients with endocarditis, in three of four atypical cases of appendicitis, in two of two infected vascular grafts, and in one of one patient with pericarditis. Subacute and chronic infections of the spine always showed photopenic areas in eight of eight patients. If photopenic lesions were included as diagnostic criteria, the sensitivity and specificity were 88% and 67%, respectively. CONCLUSIONS: Tc-99m-labeled antigranulocyte monoclonal antibody Fab' fragments can be used for imaging acute infections of peripheral bones and soft tissues. False-negative results are likely in patients with chronic infections. Sensitivity can be increased while decreasing specificity by including photopenic lesions in the spine as diagnostic criteria for localizing disease.

Follow-up of perfusion defects in pulmonary perfusion scanning after pulmonary embolism: are we too careless?

Persisting perfusion defects may still be found in pulmonary perfusion scintigraphy months or years after pulmonary embolism. The aim of this study was to investigate the rate of persisting perfusion defects and the pattern of scintigraphic follow-up of patients after pulmonary embolism. Only those patients were included into our study who received pulmonary perfusion scintigraphy between 1991 and 1999, and who had perfusion defects including at least one whole segment. These perfusion defects were considered as persisting perfusion defects if unchanged over at least 1 year. From 3640 patients examined, 451 (12.4%) had perfusion defects meeting the criteria of this study. Of those, 129 (28.6%) received a scintigraphic follow-up. In 62 patients (48.1%), a reperfusion of the defects was found. In 38 patients (29.5%), the defects persisted within a follow-up period of up to 12 weeks. However, no pulmonary perfusion scintigraphy was performed thereafter. Out of the 129 patients receiving a scintigraphic follow-up, only 29 (22.5%) had a follow-up over more than 1 year, 19 of those had persisting perfusion defects. It is concluded that our data show an inadequate scintigraphic follow-up of patients with pulmonary embolism which may lead to unnecessary anticoagulant treatment if persisting perfusion defects are misinterpreted as fresh pulmonary embolism. In many cases, there was no further follow-up even if reperfusion of the defects was lacking in early follow-up.

18F-FDG hybrid PET in patients with suspected spondylitis.

This study investigated the value of fluorine-18 2'-deoxy-2-fluoro- D-glucose (FDG) imaging with a double-headed gamma camera operated in coincidence (hybrid PET) detection mode in patients with suspected spondylitis. Comparison was made with conventional nuclear medicine imaging modalities and magnetic resonance imaging (MRI). Sixteen patients with suspected spondylitis (nine male, seven female, mean age 59 years) prospectively underwent FDG hybrid PET (296 MBq) and MRI. For intra-individual comparison, the patients were also imaged with technetium-99m methylene diphosphonate (MDP) (555 MBq) ( n=13) and/or gallium-67 citrate (185 MBq) ( n=11). For FDG hybrid PET, two or three transverse scans were performed. Ratios of infected (target) to non-infected (background) (T/B) vertebral bodies were calculated. MR images were obtained of the region of interest. Patients found positive for spondylitis with MRI and/or FDG hybrid PET underwent surgical intervention and histological grading of the individual infected foci. Twelve out of 16 patients were found to be positive for spondylitis. Independent of the grade of infection and the location in the spine, all known infected vertebrae ( n=23, 9 thoracic, 12 lumbar, 2 sacral) were detected by FDG hybrid PET. T/B ratios higher than 1.45+/-0.05 (at 1 h p.i.) were indicative of infectious disease, whereas ratios below this value were found in cases of degenerative change. FDG hybrid PET was superior to MRI in patients who had a history of surgery and suffered from a high-grade infection in combination with paravertebral abscess formation ( n=2; further computed tomography was needed) and in those with low-grade spondylitis ( n=2, no oedema) or discitis ( n=2, mild oedema). False-positive 67Ga citrate images ( n=5: 2 spondylodiscitis, 1 aortitis, 1 pleuritis, 1 pulmonary tuberculosis) and 99mTc-MDP SPET ( n=4: 1 osteoporosis, 2 spondylodiscitis, 1 fracture) were equally well detected by FDG hybrid PET and MRI. No diagnostic problems were seen in the other patients ( n=5). In this study, FDG hybrid PET was superior to MRI, 67Ga citrate and (99m)Tc-MDP, especially in patients with low-grade spondylitis (as compared with MRI), adjacent soft tissue infections (as compared with 67Ga citrate) and advanced bone degeneration (as compared with 99mTc-MDP).