Mechanism of gallium 67 accumulation in inflammatory tissue

Usefulness of gallium-67 scintigraphy for evaluating the histopathological activity in interstitial nephritis

BACKGROUND

Interstitial nephritis is a common cause of renal failure. Gallium-67 scintigraphy is reportedly useful for diagnosing interstitial nephritis; however, its ability to assess disease activity remains unknown. We aimed to analyze the relationship between the renal uptake of gallium-67 and the disease activity in interstitial nephritis.

METHODS

We retrospectively analyzed the data of patients who underwent gallium-67 scintigraphy at a hospital in Tokyo. The renal uptake adjusted for the soft tissues beneath the kidneys was semi-quantitatively evaluated. We compared the renal uptake levels between patients clinically diagnosed with and without interstitial nephritis. Among those undergoing renal biopsy, we evaluated the predictive ability of gallium-67 scintigraphy and analyzed the renal uptake levels regarding the disease activity through a histopathological analysis.

RESULTS

We included 143 patients; among them, 30, 17, and 96 patients were clinically diagnosed with interstitial nephritis, other kidney diseases, and non-kidney diseases, respectively. The renal uptake of gallium-67 was the highest among patients with interstitial nephritis. Among the 25 patients who underwent renal biopsy, 15 were pathologically diagnosed with interstitial nephritis. The renal uptake levels showed a high discriminative ability (C-statistic: 0.83). Furthermore, net reclassification improvement with the addition of gallium-67 scintigraphy to N-acetyl-β-D-glucosaminidase for the prediction of interstitial nephritis was 1.14. Histopathological analysis revealed a positive correlation between renal uptake and inflammation in the cortex and peritubular capillaries.

CONCLUSIONS

This study confirmed the diagnostic value and potential usefulness of gallium-67 scintigraphy for evaluating interstitial nephritis.

Non-invasive radionuclide imaging of trace metal trafficking in health and disease: "PET metallomics"

Several specific metallic elements must be present in the human body to maintain health and function. Maintaining the correct quantity (from trace to bulk) and location at the cell and tissue level is essential. The study of the biological role of metals has become known as metallomics. While quantities of metals in cells and tissues can be readily measured in biopsy and autopsy samples by destructive analytical techniques, their trafficking and its role in health and disease are poorly understood. Molecular imaging with radionuclides - positron emission tomography (PET) and single photon emission computed tomography (SPECT) - is emerging as a means to non-invasively study the acute trafficking of essential metals between organs, non-invasively and in real time, in health and disease. PET scanners are increasingly widely available in hospitals, and methods for producing radionuclides of some of the key essential metals are developing fast. This review summarises recent developments in radionuclide imaging technology that permit such investigations, describes the radiological and physicochemical properties of key radioisotopes of essential trace metals and useful analogues, and introduces current and potential future applications in preclinical and clinical investigations to study the biology of essential trace metals in health and disease.

Evaluation of doxorubicin-induced early multi-organ toxicity in male CD1 mice by biodistribution of 18F-FDG and 67Ga-citrate. Pilot study

The search for methods that identify early toxicity, induced by chemotherapy, is urgent. Changes in the biodistribution of radiopharmaceuticals could give information on early toxicity. Ten-week-old CD1 male mice were divided into four groups. Two groups were administered a weekly dose of 5 mg/kg of doxorubicin hydrochloride (DOX) for 5 weeks and the control groups were administered saline solution. One week after the end of treatment, the biodistribution of ¹⁸F-FDG and ⁶⁷Ga-citrate were carried out, as was the quantification of plasma enzymes CK, CK-MB, LDH and AST. All enzymes were higher in the treated animals, but only significant (p < 0.05) in the case of CK-MB. ¹⁸F-FDG uptake increased in all organs of treated animals except retroperitoneal fat, being significant in spleen, brain, heart, liver, lung, kidney, and inguinal fat. ⁶⁷Ga-citrate had a more complex pattern. The uptake in the DOX group was higher in spleen, lung, kidney, testes, and gonadal fat, it did not change in brain, heart, and liver, and it was lower in the rest of the organs. It only showed significant differences in lung and pancreas. A thorough discussion of the possible causes that produced the change in biodistributions of both radiopharmaceuticals is included. The pilot study showed that both radiopharmaceuticals could identify early multi-organ toxicity induced by DOX. Although ¹⁸F-FDG seems to be better, ⁶⁷Ga-citrato should not be ruled out a priori. The detection of early toxicity would serve to adopt treatments that prevent its progression, thus improving patient's quality of life.

Clinical Applications for Radiotracer Imaging of Lower Extremity Peripheral Arterial Disease and Critical Limb Ischemia

Peripheral arterial disease (PAD) is an atherosclerotic occlusive disease of the non-coronary vessels that is characterized by lower extremity tissue ischemia, claudication, increased prevalence of lower extremity wounds and amputations, and impaired quality of life. Critical limb ischemia (CLI) represents the severe stage of PAD and is associated with additional risk for wound formation, amputation, and premature death. Standard clinical tools utilized for assessing PAD and CLI primarily focus on anatomical evaluation of peripheral vascular lesions or hemodynamic assessment of the peripheral circulation. Evaluation of underlying pathophysiology has traditionally been achieved by radiotracer-based imaging, with many clinical investigations focusing on imaging of skeletal muscle perfusion and cases of foot infection/inflammation such as osteomyelitis and Charcot neuropathic osteoarthropathy. As advancements in hybrid imaging systems and radiotracers continue to evolve, opportunities for molecular imaging of PAD and CLI are also emerging that may offer novel insight into associated complications such as peripheral atherosclerosis, alterations in skeletal muscle metabolism, and peripheral neuropathy. This review summarizes the pros and cons of radiotracer-based techniques that have been utilized in the clinical environment for evaluating lower extremity ischemia and common pathologies associated with PAD and CLI.

The utility of PET/CT with (68)Ga-DOTATOC in sarcoidosis: comparison with (67)Ga-scintigraphy

OBJECTIVE

This study was designed to compare the clinical efficacy of (68)Ga-DOTA-Tyr-octreotide (DOTATOC)-positron emission tomography (PET)/computed tomography (CT) with that of conventional (67)Ga-scintigraphy (GS), and to correlate quantitative parameters on DOTATOC-PET/CT with clinical data, in patients with sarcoidosis.

METHODS

Twenty patients who were histologically and/or clinically diagnosed with sarcoidosis and underwent both DOTATOC-PET/CT and GS were analyzed in this study. The numbers of patients with positive findings for each organ were determined. The total numbers of involved nodal areas in the chest, as determined by DOTATOC-PET and gallium single-photon emission tomography (Ga-SPECT), were compared. The correlations between quantitative parameters on PET and clinical laboratory data were evaluated.

RESULTS

DOTATOC-PET/CT was positive in 19 patients, being negative in only one patient with chronic inactive sarcoidosis, whereas GS was positive in 17 patients. DOTATOC-PET/CT visualized more lesions in lymph nodes, uvea, and muscles than did Ga-scintigraphy and identified more involved areas than did GS-SPECT (p < 0.0001). Whole-body active lesion volume showed a significant, but moderate correlation with angiotensin-converting enzyme level (ρ = 0.64, p = 0.0044).

CONCLUSIONS

PET/CT with DOTATOC may be superior to conventional GS in detecting sarcoidosis lesions, especially in lymph nodes, uvea, and muscles. Volumetric parameters in DOTATOC-PET/CT may be helpful in estimating the activity of sarcoidosis.

Diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection by coupling hybrid 67Ga SPECT/CT with bedside percutaneous bone puncture

OBJECTIVE

Successful treatment of osteomyelitis is more likely with accurate diagnosis and identification of the causative pathogens. This typically requires obtaining a specimen of bone, usually by image-guided biopsy. We sought to develop a simpler bedside method for definitively diagnosing osteomyelitis.

RESEARCH DESIGN AND METHODS

Over 2 years, we enrolled consecutive patients presenting to our diabetic foot clinic with a foot ulcer and clinically suspected osteomyelitis but without soft tissue infection. Each underwent hybrid (67)Ga single-photon emission computed tomography and X-ray computed tomography (SPECT/CT) imaging; those with a positive scan underwent bedside percutaneous bone puncture. Patients with a positive bone culture received culture-guided antibiotic therapy. Patients with negative (67)Ga SPECT/CT imaging or with positive imaging but negative bone culture were not treated with antibiotics. All patients were followed up for ≥ 1 year.

RESULTS

Among 55 patients who underwent (67)Ga SPECT/CT imaging, 13 had negative results and all of their foot ulcers resolved without antibiotic therapy. Among 42 with positive imaging, 2 were excluded (for recent antibiotic therapy) and 40 had bone punctures (3 punctured twice): 19 had negative results, 3 of which were likely false negatives, and 24 had positive results (all gram-positive cocci). At follow-up, 3 patients had died, 3 had undergone amputation, and 47 had no evidence of foot infection. The sensitivity and specificity of this combined method were 88.0 and 93.6%, respectively, and the positive and negative predictive values were 91.7 and 90.7%, respectively.

CONCLUSIONS

Coupling of (67)Ga SPECT/CT imaging and bedside percutaneous bone puncture appears to be accurate and safe for diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection, obviating the need for antibiotic treatment in 55% of suspected cases.

[Case of temporal arteritis: FDP-PET ((18)F-fluorodeoxyglucose-positron emission tomography) was useful for early diagnosis and treatment]

A 61-year-old woman with a continuous left temporal headache and a fever of 39°C for about one month was admitted to our hospital. The physical examination was not remarkable, except for slight tenderness of the left temporal side of her head. Laboratory data on admission revealed an increase of leucocytes (9,700/µl), blood platelets (59.4×10(4)/µl), and serum c-reactive protein (CRP) (10.9 mg/dl). The erythrocyte sedimentation rate (ESR) was also elevated (88 mm/1 h). After gallium scintigraphy, a gallium-67 uptake was weakly detected at the left temporal side of her head. However, after FDG-PET examination, a high FDG uptake was detected in her temporal artery, abdominal aorta, and bilateral femoral arteries. Moreover, Doppler sonography showed a hypoechoic halo around her left temporal artery. After treatment with oral prednisolone (40 mg/day), her headache disappeared and her serum CRP level returned to normal. Finally, the patient had pathological temporal arteritis proven by a biopsy. It is difficult to make an early diagnosis of temporal arteritis if the dilatation or swelling of the temporal arteries is not present. FDG-PET is considered a useful examination not only for the exploration of tumors, but also for the evaluation of the inflammation of large vessels.

Effectiveness of prolonged fasting 18f-FDG PET-CT in the detection of cardiac sarcoidosis

BACKGROUND

The Japanese Ministry of Health and Welfare guidelines (JMHWG) are currently the standard used to diagnose cardiac sarcoidosis. JMHWG incorporate (67)Gallium scintigraphy as a minor criterion, while fasting (18)fluorine-2-fluoro-2-deoxy-D-glucose (FDG) PET is not included. As there is no published data comparing the accuracy of prolonged fasting FDG PET-CT (PF-PET) and Gallium scintigraphy for detecting active cardiac sarcoidosis, we sought to compare these two modalities.

METHODS AND RESULTS

We retrospectively reviewed medical records and nuclear images of 76 patients with suspected cardiac sarcoid who had either PF-PET or Gallium scintigraphy between January 2004 and August 2008. Eleven patients were excluded due to inadequate fasting for PF-PET, incomplete records or diagnosis other than sarcoid. Cardiac catheterizations, electrocardiogram interpretations, echocardiography reports, pathology reports, therapeutic interventions, and follow-up findings were correlated to PF-PET and Gallium scintigraphy results. Nuclear images of all patients including controls were reviewed independently by two experienced nuclear physicians blinded to results. Using JMHWG as reference standard, sensitivity, specificity, and accuracy of PF-PET were 85%, 90%, and 86.7% and for Gallium scintigraphy were 15%, 80%, and 42.8%.

CONCLUSIONS

Relative to Gallium scintigraphy, PF-PET appears to provide greater accuracy for detecting cardiac sarcoidosis. Our findings also highlight the importance of revising JMHWG to incorporate PF-PET and the importance of adequate prolonged fasting prior to FDG PET imaging.

Thyroid uptake of 67Ga-citrate is associated with thyroid autoimmunity and hypothyroidism in patients with sarcoidosis

PURPOSE

To evaluate the association of gallium-67 ((67)Ga)-citrate thyroid uptake with the presence of thyroid disorders in patients with sarcoidosis (S patients).

METHODS

Eighty-four S patients were evaluated by a complete thyroid work-up (neck ultrasound, circulating thyroid hormones and anti-thyroid antibodies, fine-needle aspiration).

RESULTS

In S patients with (67)Ga thyroid uptake (respect those without): serum thyroid-stimulating hormone, the titre of anti-thyroid peroxidase (AbTPO) and/or anti-thyroglobulin antibodies (AbTg), and the prevalence of S patients with hypothyroidism or with positive AbTg or AbTPO was significantly higher; a thyroid hypoechoic pattern was more frequent. The prevalence of thyroid nodules was not significantly different between the two groups. Two cases of papillary thyroid cancer were observed in S patients without (67)Ga thyroid uptake, whilst no case in those with (67)Ga thyroid uptake.

CONCLUSIONS

(67)Ga thyroid uptake is associated with the presence of aggressive autoimmune thyroiditis and hypothyroidism in S patients; thyroid function and ultrasonography should be performed in the presence of (67)Ga thyroid uptake.

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.

Clinical value of gallium-67 scintigraphy in assessment of disease activity in Wegener's granulomatosis

BACKGROUND

Diagnosis of active pulmonary and paranasal involvement in patients with Wegener's granulomatosis (WG) can be difficult. The diagnostic value of gallium-67 scintigraphy in WG is unclear.

OBJECTIVE

To evaluate the added diagnostic value of gallium-67 scintigraphy in patients with WG with suspected granulomatous inflammation in the paranasal and chest regions.

METHODS

Retrospectively, the diagnostic contribution of chest and head planar gallium scans in 40 episodes of suspected vasculitis disease activity in 28 patients with WG was evaluated. Scans were grouped into normal or increased uptake for each region. Histological proof or response to treatment was the "gold standard" for the presence of WG activity.

RESULTS

WG activity was confirmed in 8 (20%) episodes, with pulmonary locations in three, paranasal in four, and both in one (n=7 patients); all these gallium scans showed increased gallium uptake (sensitivity 100%). Gallium scans were negative for the pulmonary area in 23/36 scans (specificity 64%), and negative for paranasal activity in 13/16 scans (specificity 81%) in episodes without WG activity. Positive predictive value of WG activity for lungs and paranasal region was 24% and 63%, respectively, negative predictive value was 100% for both regions. False positive findings were caused by bacterial or viral infections.

CONCLUSION

Gallium scans are clinically helpful as a negative scan virtually excludes active WG. Gallium scintigraphy of chest and nasal region has a high sensitivity for the detection of disease activity in WG. However, because of positive scans in cases of bacterial or viral infections, specificity was lower.

Technetium-99m-DTPA aerosol scintigraphy in amiodarone induced pulmonary toxicity in comparison with Ga-67 scintigraphy

Amiodarone hydrochloride, which is used in life-threatening cardiac tachyarrhythmia, has been known to cause amiodarone induced pulmonary toxicity (AIPT) as a complication. In this study we aimed to investigate the clinical value of technetium-99m diethylene triamine penta-acetic acid (DTPA) aerosol lung scintigraphy in patients with AIPT in comparison with gallium-67 (Ga-67) scan. The study group included 26 cases, 7 patients with diagnosis of AIPT (Group A), 8 patients receiving amiodarone therapy but without AIPT (Group B) and 11 healthy subjects as a control group (Group C). All patients underwent Ga-67 and Tc-99m-DTPA aerosol scintigraphy in addition to various laboratory tests, Ga-67 scintigraphy was positive in 4 of 7 AIPT patients but quite normal in Group B. A positive correlation was found (r = 0.52, p < 0.05) between kep values determined by Tc-99m-DTPA aerosol scintigraphy and the cumulative dose of amiodarone. The mean kep values were 2.04% +/- 0.85%/min, 1.30% +/- 0.42%/min and 0.86% +/- 0.19%/min for groups A, B and C, respectively. The mean clearance rate of group A was significantly faster than that of normals (p < 0.0005) and group B (p = 0.028). In addition, there was a significant difference between groups B and C (p = 0.015). In conclusion, Ga-67 lung scintigraphy is a useful method for the detection of AIPT but Tc-99m-DTPA aerosol scintigraphy offers better results than Ga-67 scintigraphy. Early changes in Tc-99m-DTPA clearance may be observed in patients receiving amiodarone. The kep value in patients with AIPT is noticeably increased with respect to the control group. With its favorable physical properties, low cost, lower radiation burden and its ability to be used as an objective measure for the pulmonary clearance rate, Tc-99m-DTPA aerosol scintigraphy appears to be promising in patients receiving amiodarone therapy.

Effect of imaging time on gallium renal scan

AIM

Gallium renal imaging has been reported to be useful in monitoring disease activity and predicting the response to therapy in lupus nephritis. Gallium renal images are usually obtained 48 h after the injection of 67Ga citrate, but 72-h images sometimes are the only available pictures. The aim of the present study was to determine whether the time intervals from injection to imaging had any effect on the grading of gallium renal scintigraphy.

METHODS

Fifty-five patients with lupus nephritis underwent gallium renal imaging at both 48 h and 72 h post-injection of 111 MBq of 67Ga citrate. The relative uptakes of 67Ga by the kidneys and the spine was judged visually on the analog images. Renal uptake was rated on a scale of 0-3.

RESULTS

Fifty-three patients (96.3%) had the same grading of renal uptake in the 48-h and the 72-h images. Only two patients (3.7%) had a different grading in the 72-h images when compared to the 48-h images. The correlation between the 48-h renal uptake and 72-h renal uptake was excellent, with a Spearman R value of 0.94. No significant difference was noted between these two groups, with a P value of 0.76 (using a Wilcoxon matched pairs test).

CONCLUSION

A gallium renal scan can be obtained either 48 h or 72 h after injecting 67Ga citrate. The imaging time did not interfere with the grading of renal uptake in lupus nephritis.

Ga-67 uptake in cutaneous lesions of graft-versus-host disease

Acute graft-versus-host disease (GVHD) usually involves the skin, gastrointestinal tract, and liver. A 47-year-old woman with fever of unknown origin was referred for a Ga-67 scan. The study showed diffuse uptake of Ga-67 throughout the skin. Subsequently, a skin biopsy confirmed the diagnosis of acute GVHD. The incidence, diagnosis, and pathophysiology of the dermatitis in acute GVHD are discussed.

Gallium-67 scintigraphy in macrophagic myofasciitis

OBJECTIVE

To evaluate gallium-67 (67Ga) uptake and the value of 67Ga scintigraphy for diagnosis of macrophagic myofasciitis (MMF), a recently identified inflammatory myopathy.

METHODS

Twelve consecutive patients with MMF confirmed by muscle biopsy, 10 with polymyositis, 10 with sarcoidosis, 8 with fibromyalgia, and 10 with lymphoma without muscle symptoms (serving as normal controls for muscle) were included. Patients received 1.8 MBq 67Ga per kg body weight by intravenous injection, and scintigraphy was performed with a 2-head gamma camera. The various views were acquired for the 3 main photopeaks of 67Ga 48 hours after infusion, and were analyzed in 2 blinded experiments by nuclear physicians. A semiquantitative scale was used to compare the uptake of 67Ga in the vascular soft tissue background with that in the muscles or joints of MMF patients, and with that in the normal controls.

RESULTS

The MMF patients (4 men and 8 women, mean +/- SD age 47.8 +/- 8.7 years) had chronic myalgia (n = 11; predominantly in the lower limbs), asthenia (n = 10), arthralgia (n = 7), mild muscle weakness (n = 5), and high serum creatine kinase levels (n = 6). All MMF patients had significantly higher levels of 67Ga uptake in the muscle and para-articular areas than that recorded for the soft tissue background and for the controls. Muscle uptake was bilateral, symmetric, and homogeneous, and predominantly localized in the legs. No linear enhancement corresponding to fascias or synovial involvement was observed. In patients with polymyositis, symmetric, but heterogeneous, 67Ga uptake was observed in muscle, but not in the fascia. In patients with sarcoidosis, 67Ga uptake was nodular and heterogeneous in muscle, was not detected in the fascia, and was suggestive of synovial involvement in the joints. The uptake of 67Ga in fibromyalgic patients was similar to that in normal controls and to that in the soft tissue background.

CONCLUSION

MMF is a new condition involving characteristic changes that can be detected by deltoid muscle biopsy. It usually manifests as a weakly specific, chronic arthromyalgic syndrome that predominates in the lower limbs. 67Ga scintigraphy is a noninvasive method that may make it easier to differentiate MMF from fibromyalgia and sarcoidosis.

Temporal 67gallium uptake is increased in temporal arteritis

OBJECTIVE

We evaluated temporal 67gallium (Ga) uptake in temporal arteritis (TA) and the contribution of Ga scans to the diagnosis of TA.

METHODS

Ga scans were performed prospectively in 19 patients with biopsy-proven TA and five TA patients with negative temporal artery biopsy. Controls were 18 elderly patients undergoing Ga scans for various inflammatory diseases. The temporal region of interest on head profiles was defined for comparison of uptake with a control parietal region of the same area. The Ga uptake ratio (GaUR) [(temporal region - parietal region)/parietal region] was evaluated for each temple by a computer and intra- and intergroup comparisons were made.

RESULTS

GaUR was significantly higher in biopsy-proven TA patients (0.35+/-0.19) and biopsy-negative TA patients (0.31+/-0.03) than in controls (0.18+/-0.12) (P < 0.001), independently of recent temporal artery biopsy or short-duration steroid therapy. High GaUR (>0.4) had a 94% specificity and a 90% positive predictive value for TA diagnosis. After 6 months of steroid therapy, when patients were in remission, GaUR returned to baseline.

CONCLUSION

Ga is specifically incorporated into the temporal area in TA patients which may be due to the granulomatous vasculitic process. Ga uptake ceases during remission. A high GaUR may contribute to TA diagnosis in temporal artery biopsy-negative patients and its role in the diagnosis of other localizations of the disease requires further evaluation.

Radionuclide targeting and dosimetry at the microscopic level: the role of microautoradiography

The understanding of localisation mechanisms and microdosimetry of diagnostic and therapeutic radiopharmaceuticals depends on knowledge of their biodistribution at the microscopic level (cellular and subcellular) in the target tissues. Various methods have been advanced for obtaining information about this microdistribution: subcellular fractionation, secondary ion mass spectrometry imaging, microprobe elemental analysis in the electron microscope, and microautoradiography. This review compares these approaches, and discusses in detail the methodology of microautoradiography (the most generally useful approach) with imaging and therapy radionuclides. Literature examples of applications of microautoradiography in nuclear medicine are reviewed, and the future potential contribution of the techniques is assessed.

Developmental toxicity evaluation of gallium nitrate in mice

Gallium nitrate, a drug with antitumor activity, is presently undergoing clinical trials as a chemotherapeutic agent for the treatment of certain malignancies. Since there are very limited published animal toxicity data available, this study was conducted to investigate the potential adverse developmental effects of this drug. Pregnant Swiss mice were administered intraperitoneally gallium nitrate at 12.5, 25, 50, and 100 mg/kg/day on days 6, 8, 10, 12, and 14 of gestation. Monitors for maternal toxicity were body weight, food consumption and clinical signs. At sacrifice (day 18) maternal weight, liver and kidney weights, and gravid uterine weights were measured. Gestational parameters monitored were numbers of total implants, resorptions, postimplantation losses, and dead fetuses. Live fetuses were sexed, weighted, and examined for external, internal and skeletal malformations and variations. Maternal toxicity was noted in all the gallium nitrate-treated groups. Embryo/fetal toxicity was evidenced by a decrease in the number of viable implants, a reduction in fetal weight, and an increase in the number of skeletal variations (12.5, 25, 50 and 100 mg/kg). No significant increase in the incidence of malformations was observed at 12.5, 25, or 50 mg/kg. The no-observable-adverse-effect level (NOAEL) for both maternal and developmental toxicity of gallium nitrate was less than 12.5 mg/kg.