Temporal 67gallium uptake is increased in temporal arteritis

Granulocyte Colony-stimulating Factor-associated Aortitis on Gallium Scintigraphy

Aortitis is a rare adverse event associated with granulocyte colony-stimulating factor (G-CSF). Contrast-enhanced computed tomography (CECT) is widely used to diagnose G-CSF-associated aortitis. However, the usefulness of gallium scintigraphy for the diagnosis of G-CSF-associated aortitis is unknown. We herein report a set of pre- and post-treatment gallium scintigrams of a patient with G-CSF-associated aortitis. During the diagnosis, gallium scintigraphy revealed hot spots on the arterial walls that appeared inflamed on CECT. Both the CECT and gallium scintigraphy findings disappeared. Gallium scintigraphy can be a supportive diagnostic tool for G-CSF-associated aortitis, especially in patients with an impaired renal function or allergy to iodine contrast.

Decreased sensitivity of (18)F-fluorodeoxyglucose imaging in infection and inflammation

Nuclear medicine plays an important role in the evaluation of inflammation and infection. Although (99m)Tc-methylene diphosphonate, (67)Ga-citrate, and in vitro labeled autologous leukocyte imaging are useful procedures, there are limitations to each of them. (18)F-fluorodeoxyglucose-positron-emission tomography (PET) and PET/computed tomography offer several advantages over conventional single-photon-emitting tracers and has proved to be a valuable addition to the nuclear medicine infection imaging armamentarium. PET provides high-resolution 3-dimensional images of the whole body that facilitates precise localization of abnormalities. Localization is enhanced with PET/computed tomography. Fluorodeoxyglucose, for the most part, is exquisitely sensitive with a high negative predictive value. In general, the limiting factor of the test is specificity. However, there are some situations in which the limitation to the test is not low specificity but rather low sensitivity.

[Vasculitis assessment with [18F]FDG positron emission tomography]

[18F]fluorodeoxyglucose positron emission tomography (PET) is a noninvasive metabolic imaging modality that is well-suited to the assessment of activity and extent of large vessel vasculitis. PET imaging has demonstrated its usefulness in diagnosing giant cell arteritis (notably in its silent form), Takayasu's arteritis, and unclassified aortitis. PET imaging could be more effective than magnetic resonance imaging in detecting the earliest stages of vascular wall inflammation. The visual grading of vascular [18F]FDG uptake makes it possible to discriminate arteritis from active atherosclerosis, providing therefore high specificity. High sensitivity can also be achieved provided scanning is performed during active inflammatory phase, preferably before starting corticosteroid treatment. Prospective studies are needed to determine the exact value of PET imaging in assessing other vasculitis subsets, infectious aortitis, and large vessel vasculitis outcome and response to immunosuppressive treatment.

Small animal PET for the evaluation of an animal model of genital infection

BACKGROUND

[(18)F]-FDG is a widely used tracer for the non-invasive evaluation of hypermetabolic processes like cancer and inflammation. However, [(18)F]-FDG is considered inaccurate for the diagnosis of urinary tract and genital infections because of its urinary excretion. Since the 1970s, Gallium scintigraphy is a well established test that has been used for the evaluation of inflammation and infection in human patients.

AIM

The aim of this study was to assess the feasibility of (68)Ga-Chloride small animal PET for the analysis of an animal model of genital infection, induced after the vaginal inoculum of Chlamydia muridarum. Material and Thirty mice were infected by placing 15 microl sucrose phosphate glutamic acid (SPG) 10(7) inclusion forming units of C. muridarum into the vaginal vault. As controls of inflammation, three animals were challenged with 15 microl of SPG and one healthy animal was used to assess the tracer biodistribution. Four animals died during the experiment. Eleven animals were evaluated with (68)Ga-Chloride small animal PET (GE, eXplore Vista) 3-5, 10-12, 17-19 days after infection, as well as three controls of inflammation and one healthy animal. Infection was monitored by obtaining cervical-vaginal swabs from all the animals on the day of each PET procedure. Moreover, five groups of three animals each were killed at 6, 13, 20, 27 and 34 days after infection were studied.

RESULTS

(68)Ga-PET turned out positive in all the infected animals, concordantly to data obtained by the cervical swabs and by the ex vivo analysis. The tumour-to-background ratio (TBR) decreased over time as the inflammation tended to naturally extinguish. The controls showed a slightly increased uptake of tracer due to the aseptic inflammation caused by SPG and frequent cervical swabs. The healthy control did not show any pelvic uptake.

CONCLUSION

(68)Ga-Chloride is a promising tracer for the assessment of genital infection in a mouse animal model.

Increased 67gallium uptake among polymyalgia rheumatica patients. Is it additional evidence of its vasculitic nature?

Giant cell arteritis/temporal arteritis (GCA/TA) and polymyalgia rheumatica (PMR) are closely related conditions that affect middle age and older patients and frequently occur together. Many authorities consider them to be different phases of the same disease. A study was undertaken of the possible contribution of gallium-67 ((67)Ga) single photon emission tomography (SPECT) scintigraphy to the diagnosis of GCA/TA and PMR, and to support the possible hypothesis of vasculitic nature of PMR. Nine consecutive patients with PMR, and nine consecutive patients with GCA/TA were included in the study. All patients fulfilled the American College of Rheumatology criteria for GCA/TA and Healey's criteria for PMR. The control patients group consisted of those who underwent (67)Ga scintigraphy for febrile illness. All patients and controls underwent (67)Ga SPECT scan of the skull on a dual-head Helix gamma camera 2 days after I.V. injection of 8-10 mCi of (67)Ga citrate. (67)Ga uptake ratio of temporal bone region to bone out of temporal area (TR/Bone) was estimated on transaxial and coronary slices after SPECT scan reconstruction. For each patient and control the calculations of both temporal areas were done. All GCA/TA and PMR patients showed increased uptake in both temporal areas of the skull, while (67)Ga uptake among GCA/TA was the highest, 1.31+/-0.14 in tranaxial view and 1.47+/-0.16 in coronary view. (67)Ga uptake among PMR patients was lower, 1.19+/-0.11 and 1.28+/-0.13, respectively. In comparison, the control patients showed the lowest (67)Ga uptake, 1.04+/-0.09 in transaxial view and 1.11+/-0.06 in coronary view. The results differ significantly between the three groups. It seems that (67)Ga SPECT scan may become a useful tool in the investigation of patients with suspicion of GCA/TA and PMR. Our findings of the increased (67)Ga uptake in the temporal areas among PMR patients add new arguments for vasculitic nature of this disorder.

Giant cell arteritis: strategies in diagnosis and treatment

PURPOSE OF REVIEW

This review summarizes current diagnostic assessments and therapeutic strategies in giant cell arteritis. Giant cell arteritis or temporal arteritis is a chronic vasculitis of large and medium-size vessels. Concurrent symptoms of proximal muscular ache and morning stiffness, polymyalgia rheumatica, are commonly seen. Recent investigations support the contention that polymyalgia rheumatica and temporal arteritis are two different expressions of the same underlying vasculitic disorder.

RECENT FINDINGS

The symptomatology of giant cell arteritis is quite varying. Recently a frequent occurrence of audiovestibular manifestations was demonstrated, which should be actively searched for in the clinical investigation. Although color Doppler ultrasound, MRI, and positron emission tomography have illustrated the widespread nature of giant cell arteritis, none of these techniques may currently replace temporal artery biopsy. Biopsy of the superficial temporal artery is a safe and simple procedure, and remains the gold standard for the diagnosis of giant cell arteritis. The importance of long biopsies and meticulous histologic examination using sub-serial sectioning is emphasized. Numerous recent publications confirm the low diagnostic yield of a second, contralateral biopsy. Corticosteroids remain the cornerstone in the treatment of giant cell arteritis. Although steroid treatment promptly eliminates symptoms of systemic inflammation, its effect on inflammatory morphology is delayed. Consequently, there is a need for new therapeutic strategies. The potential role of aspirin has recently been implicated.

Giant cell arteritis

Giant cell arteritis (GCA), temporal arteritis or Horton's arteritis, is a systemic vasculitis which involves large and medium sized vessels, especially the extracranial branches of the carotid arteries, in persons usually older than 50 years. Permanent visual loss, ischaemic strokes, and thoracic and abdominal aortic aneurysms are feared complications of GCA. The treatment consists of high dose steroids. Mortality, with a correct treatment, in patients with GCA seems to be similar that of controls.

Role for vascular investigations in giant cell arteritis

Giant cell arteritis is characterized by diffuse arterial inflammation that selectively involves the superficial temporal arteries but can occur in larger arteries. Various vascular investigations can assist in diagnosing and evaluating the extent of giant cell arteritis. Imaging techniques, mainly Doppler ultrasonography of the superficial temporal arteries, seem less reliable for the diagnosis than temporal artery biopsy, which is safe and remains indispensable. Investigations of larger arteries can detect asymptomatic stenotic lesions, which are common, particularly in the axillary and subclavian arteries. Involvement of the aorta can cause life-threatening dissection or aneurysmal rupture. Imaging techniques useful for diagnosing aortic involvement include ultrasonography, computed tomography, magnetic resonance imaging, and aortography. Although there is no standardized strategy for aortic lesion detection, helical computed tomography may be valuable.

Giant cell arteritis: diagnosis and management

Visual loss caused by giant cell arteritis is a medical emergency that requires prompt recognition and treatment with systemic corticosteroids. A delay in diagnosis can lead to devastating ophthalmic and systemic complications. Recent advances in genetic and immunocytochemical research techniques have led to greater understanding of the underlying pathomechanisms of giant cell arteritis. Giant cell arteritis is a systemic condition with a strong predilection for the ocular vasculature. Visual symptoms are often the presenting manifestation of the disease, placing the ophthalmologist in a critical position for early diagnosis and treatment. Maintenance of a high clinical suspicion in the appropriate clinical setting is important in establishing an early diagnosis. Because of the complex nature of the disease process, many cases may be a therapeutic challenge requiring prolonged immunosuppression.

Diagnosis of vasculitis

Vasculitis is a process that results from the inflammation of blood vessels and can occur de novo or secondary to a variety of diseases or drugs. Clinical presentation depends on the size and distribution of vessels involved. Anti-neutrophil cytoplasmic antibodies (ANCA) have been shown to have variable sensitivity in making the diagnosis of specific vasculitic syndromes, therefore histological confirmation may be necessary. Angiography is a useful tool in evaluating disease of large and medium-sized vessels that are inaccessible or potentially dangerous to biopsy. New imaging modalities are becoming more useful in diagnosing vessel wall changes, particularly in large-vessel vasculitides. In clinical practice it is not always possible to classify or apply a specific label to a patient with vasculitis, but for appropriate patient management it is important to define the extent and severity of disease and to exclude underlying secondary causes.

Giant Cell Arteritis

Giant cell arteritis is a medium-vessel vasculitis that affects both men and women. Because the disease commonly presents with nonspecific complaints stemming from cranial arterial insufficiency, the challenge for the physician is recognizing the diagnosis. Recognition of the entity and expeditious initiation of therapy are required to prevent permanent complications, including blindness. There is no pathognomonic finding on physical examination, blood testing, or commonly used radiologic investigations to confirm the diagnosis or establish disease activity. Oral corticosteroids are the mainstay of therapy. Other immune system modulators have no demonstrated efficacy and require further investigation. Percutaneous or surgical revascularization is a viable therapeutic option when the disease is not active.