Gallium Scan Research Articles

R-CHOP in the Treatment of DLBCL: Single Institution Experience from North India.

Diffuse large B-cell lymphoma (DLBCL) is the most frequent type of NHL. Different chemotherapy regimens tested in the past showed RR of appx 80% with no improvement in prognosis & OS. CHOP regimen has been the standard treatment for these patients (pts). Rituximab has improved response rates & survival in CD20 positive lymphoma pts, especially elderly (GELA trial: CR 73% vs. 63%). We retrospectively evaluated pts of DLBCL treated with R-CHOP regimen between April 2001 & June 2005. All pts had biopsy and IHC of lymph node/extranodal site, & CT scan of neck, chest, abdomen; BM biopsies; CBC, serum chemistries; 2D echocardiography/MUGA scans. All pts received Rituximab (375mg/m2) & CHOP 3 weekly for a maximum of 8 cycles. Pts who received at least 1 & 3 cycles of R-CHOP were evaluable for toxicity and response respectively. In total, 36 pts were included for analysis. The median age was 53 years, 10/36 pts (27.8%) were >60 years. 25/36 were male (69.4%). ECOG performance status: 0–1 in 30/36, and 2–4 in 6/36. 11/36 had B-symptoms, 16/36 had high LDH, 6/36 had bulky disease. Extranodal involvement was present in 19/36; 10/36 had ≥2 sites of extranodal involvement. Lymph nodal swelling was most common presentation in 24/36 (66.7%), followed by pain 10/36 (27.8%), weight loss 9/36 (25%), fever 7/36 (19.4%), skin nodules 3/36 (8.3%). Extranodal sites were: bone marrow 5/36, bone 4/36, skin 3/36, GIT 3/36, pleural effusion 2/36, lungs 2/36, other soft tissue 2/36, and parotid, nasopharynx, orbit, adrenal, testes, kidneys-1 each. Gallium scan at base line, done in 12/36, was positive in 11 pts (91%). Stage distribution was as follows: stage-I none, stage-II 10/36 (27.8%), stage-III 13/36 (36.1%), stage-IV 13/36 (36.1%). IPI scoring was-low risk 13/36 (36.1), low intermediate 9/36 (25.0%), high intermediate 13/36 (36.1) & high risk 1/36 (2.8%). A total of 199 cycles of R-CHOP were administered with a median of 6 cycles per patient. Of the 33 pts evaluable for response, 22 achieved CR (66.7%), 9 PR (27.3%), 1 each SD & PD. There were 2 treatment related mortalities. Toxicities were: grade III/IV neutropenia in 12/36 (33.3%), thrombocytopenia 4/36 (11.1%), peripheral neuropathy 2/36 (5.6%). Mild hypersensitivity to Rituximab was seen in 2/36 (5.6%) pts. Only 1 patient had cardiac toxicity in form of CHF. Our study showed response rates (94%) and toxicity profile similar to what has been reported in other studies with R-CHOP. The follow-up is too short to evaluate survival rates. Keywords: DLBCL, Rituximab, CHOP.

Neurosarcoidosis

Chronic involvement of the nervous system is relatively rare in sarcoidosis. We describe 7 cases that fulfil Zajicek's criteria for neurosarcoidosis (NS) and propose some modifications to such criteria. The patients were admitted for various neurological syndromes: 2 cases presented with chronic lymphocytic meningitis, 4 with spinal cord symptoms, one case was initially confused with multiple sclerosis. Serological tests, immunological screening, cerebrospinal fluid (CSF) analysis, bacteriological and viral testing were performed in all patients. Spinal and cerebral MRI, gallium scan, bronchoscopy with biopsy and bronchoalveolar-lavage fluid analysis, high-resolution computed tomography (HRCT) of the chest, biopsy of the lungs, skin, mediastinal lymph-node and meninges, were useful in diagnosing NS. Laboratory tests showed serum inflammatory abnormalities, but were negative for infectious diseases, while CSF showed inflammatory signs in all patients. MRI revealed meningeal enhancement or hypertrophic pachymeningeal lesions in 4 patients, white matter abnormalities and mass lesions in 2 patients, and a spinal mass lesion in 1 patient. Gallium scan, HRCT, bronchoscopy were positive in most cases. Patients were treated with steroid and immunosuppressive therapy, with improvement in six cases. One patient died from infectious complications. A definite diagnosis of NS requires demonstration of non-caseating granulomas affecting nervous tissues. In most cases, histological evidence of systemic disease (probable NS) is sufficient in the presence of compatible alterations in the CNS. In our patients the bronchoalveolarlavage fluid analysis, gallium scan, and chest HRCT were important for diagnosis, while serum ACE was always normal and chest radiographs were not suggestive of sarcoidosis.

Heerfordt Syndrome Initially Presenting With Subcutaneous Mass Lesions: Usefulness of Gallium-67 Scans Before and After Treatment

Heerfordt syndrome is characterized by parotid gland swelling, uveitis, facial nerve palsy, and fever. This syndrome is recognized as a rare special form of sarcoidosis. and the definite diagnosis of this syndrome is madehistologically according to sarcoidosis, ie, by demonstration of noncaseating epithelioid cell granulomas. Although a gallium-67 scan is helpful for the diagnosis of sarcoidosis, there have been very few reports on the usefulness of gallium-67 scan for this syndrome. We present gallium-67 scans obtained before and after treatment in a case of Heerfordt syndrome.

Multiple Bone Lesions of Systemic Multifocal Fibrosclerosis

Multiple Bone Lesions of Systemic Multifocal FibrosclerosisNorbert Blank1, Roland Repp2, Wolfgang Römer3, Joachim R. Kalden2, Gisela Helm2, Thomas Harrer2, Hanns-Martin Lorenz1 and Rolf Janka4Audio Available | Share

Kikuchi's disease in a 9-year-old girl: case report

A 9-year-old girl was admitted with a 2month history of continuous, moderate-tohigh-grade fever, weight loss and gradual onset of pallor. There was no history of cough, diarrhoea, urinary symptoms, rash or arthralgia. On examination, she was emaciated, febrile and pale. There were multiple, matted, tender cervical lymph notes of firm consistency, predominantly on the right side. Axillary and inguinal lymph nodes were not palpable. There was hepatomegaly of 3 cms. The spleen was not palpable. Hb was 6 g/dl and blood film showed a hypochromic, microcytic picture; WBCs were 2.1610/L, neutrophil count 1.2610/L and platelets 253610/L. ESR was 121 mm in the 1st hour. Cultures of blood and urine and throat swabs were sterile. Serology for cytomegalovirus (CMV) was positive, both IgG and IgM, and negative for Epstein–Barr virus. However, PCR for CMV in blood and urine was negative. A Mantoux test and PCR for mycobacteria in blood were also negative. Anti-nuclear antibody, double-stranded DNA and anti-nuclear cytoplasmic antibody were all below the reference range. Bone marrow aspirate revealed normal haematopoiesis, and trephine was normal. Chest X-ray and ultrasound of the abdomen were normal. However, CT scan of the chest showed enlarged axillary lymph nodes with dense nodules within the parenchyma of the right lung but there were no mediastinal lymphadenopathy. Gallium and bone scans were normal. Lymph node histology demonstrated multiple areas of necrosis with preservation of only a few irregular follicles. The areas of necrosis were situated peripherally and were of irregular shape and bordered by proliferating histiocytes. Within the areas of necrosis there was abundant nuclear debris. The nucleus of the histiocytes appeared to be crescent-shaped as a result of being pushed away by abundant pink cytoplasm. Polymorphonuclear leucocytes were conspicuously absent and there were no granulomas. The findings were compatible with necrotising lymphadenitis.

Primary mediastinal large B‐cell lymphoma: optimal therapy and prognostic factor analysis in 141 consecutive patients treated at memorial Sloan Kettering from 1980 to 1999

Primary mediastinal large B-cell lymphoma (PMLBL) is a distinct clinicopathological entity with unclear prognostic factors and optimal treatment approach. To elucidate an optimal treatment and identify predictive factors, a retrospective analysis of 141 consecutive patients was undertaken. Patients received cyclophosphamide, hydroxydaunomycin, Oncovin, prednisone (CHOP)-like therapy, the non-Hodgkin lymphoma (NHL)-15 regimen or upfront autologous stem cell transplantation (ASCT) on Institutional Review Board approved trials or according to the institutional guidelines. Evaluation included lactate dehydrogenase, International Prognostic Index (IPI) assessment, computed tomography scan and gallium imaging. With a median follow-up of 10.9 years, event-free survival (EFS) and overall survival (OS) was 50% and 66% respectively. EFS/OS for CHOP/CHOP-like, NHL-15 and upfront ASCT was 34/51%, 60/84% and 60/78% respectively. CHOP/CHOP-like regimens had inferior EFS and OS versus NHL-15 or upfront ASCT (P < 0.001). A total of 23% of patients received radiotherapy. Multivariate analysis revealed the following outcome predictors: for EFS, greater than or equal to two extranodal sites and initial therapy received (NHL-15 or upfront ASCT); for OS, only initial therapy with NHL-15. We conclude: (i) dose-dense chemotherapy with NHL-15 may be superior to CHOP for PMLBL; (ii) The impact of consolidative radiotherapy requires randomised controlled trials; (iii) The age-adjusted IPI did not predict survival in this analysis; (iv) high-dose chemotherapy/ASCT should be reserved for upfront anthracycline-based therapy failure or in clinical trials for high-risk patients.

A case of burkitt’s lymphoma involving both breasts

Primary malignant lymphoma of the breast is rare, and Burkitt's lymphoma is especially rare. We report the case of a 44-year-old woman in whom Burkitt's lymphoma involving both breasts was diagnosed. The patient was referred to our hospital because of a diffuse, firm swelling, like a bulky ball, in both breasts. Fine-needle aspiration cytology (FNAC) of both breast masses revealed malignant lymphoma(ML), and diffuse large B-cell lymphoma was diagnosed based on the results of immunohistochemical studies of a core needle biopsy specimen. The gallium scan revealed very hot lesions in both breasts, but there was no evidence of disseminated disease. We instituted initial therapy, with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus intrathecal chemotherapy without performing a chromosome analysis, because the clinical course was very aggressive. A CR was achieved, but after eight cycles of CHOP therapy, the ML relapsed. We then resected the mass in the left breast, and when examination of the surgical specimen revealed relapse of ML and t (8;11) (q24;q32) translocation, Burkitt's lymphoma was diagnosed. High-dose chemotherapy followed by peripheral-blood stem cell transplantation was performed, but the patient died 10 months after her initial presentation at our hospital.

Pre-transplant positive PET/Gallium scans predict poor outcome in relapsed/refractory Hodgkin’s lymphoma (HL)

6509 Background: High dose chemotherapy followed by autologous stem cell transplantion (SCT) has become the standard of care in patients (pts) with relapsed or refractory HL. Chemosensitivity, assessed by conventional tomography has been correlated with better disease free-survival (DFS) and outcome. Methods: We assessed the value of functional imaging in pts with HL referred to MDACC and treated with high dose chemotherapy followed by SCT from December 1999 to May 2004. 122 pts, male 57%, median age 31 years, (range, 10–76), with nodular sclerosis type 91%, were diagnosed at stages I (2%), II (43%), III (32%), and IV (23%). 86% of the pts were treated with ABVD-based regimens, 45% received adjuvant radiation therapy. 33% of the pts were primary refractory. Most of the pts were salvaged with ESHAP chemotherapy. At the time of salvage therapy, B symptoms were present in 45% of the pts, extra-nodal disease was documented in 23%, and relapse beyond 12 months of response occurred in 65%. Response was evaluated, before SCT, by PET scan and Gallium scan in 68 and 55 pts respectively. Results: 59% of the pts were in complete response (CR) or unconfirmed complete response (CRu), 38% were in partial response (PR), and 3% were stable by CT scan. PET scan and Gallium scan were positive in 25 of 68 (37%) and 9 of 55 (16%) pts, respectively. Relapses occurred in 44 of 122 (36%) pts. At 2 years, the cumulative probability of DFS was 65% for pts with a negative PET scan versus 30% for pts with a positive PET scan (p=0.00008), and 75% for pts with a negative Gallium scan versus 37% for pts with a positive Gallium scan (p=0.046). The positive predictive value (PPV) of the PET scan and Gallium scan were 68% and 55% respectively. The negative predictive values (NPV) were 77% and 76% respectively. Conclusions: Pre-transplant functional imaging is a strong predictive factor of DFS. Investigational therapy should be considered for pts with positive functional studies. No significant financial relationships to disclose.

Gallium Scan after the second and fourth chemotherapy cycle predicts clinical outcomes in aggressive non-Hodgkin’s lymphomas

6576 Background: Gallium scintigraphy has been used to assess response to treatment in patients receiving chemotherapy for non-Hodgkin’s lymphoma (NHL). Methods: From 1992 to 1996, 190 newly diagno...

Asymmetric Lower Extremity Muscle Activity on a Gallium Scan

A 17-year-old girl with a history of Hodgkin disease showed increased gallium accumulation in the region of the right hip and reduced uptake in the muscles of the right lower extremity. Increased gallium accumulation in the right hip was attributed to avascular necrosis and the reduced gallium activity was attributed to disuse atrophy of the right lower extremity secondary to avascular necrosis (confirmed on the CT scan).

Sixth and Tenth Nerve Palsy Secondary to Pseudomonas Infection of the Skull Base

To describe skull base osteomyelitis, an uncommon complication of chronic otitis media in the post-antibiotic era, as a cause for diplopia. Case report. The records of a patient with skull base osteomyelitis were reviewed. A patient presented with a sixth nerve palsy and tenth nerve palsy. Magnetic resonance imaging, bone scan, and gallium scan were helpful in establishing the diagnosis. Cultures grew Pseudomonas. The treatment required long-term intravenous antibiotics. Pseudomonas skull-based osteomyelitis can produce a sixth nerve palsy as a result of the involvement of the clivus. Although uncommon in the post-antibiotic era, early recognition, appropriate diagnostic testing, and aggressive systemic antibiotic treatment might prevent permanent neurologic sequel.

Discordant Response to Chemotherapy Between Lymphadenopathy and Bone Lesions on Gallium-67 Scanning in Hodgkin??s Disease

A 33-year-old woman with a diagnosis of Hodgkin's disease had a prechemotherapy whole-body Ga-67 scan to document gallium avidity of lesions and to assess response to therapy. A posttherapy scan showed a discordant response with complete resolution of lymphadenopathy and persistence of bone lesions. Radiographic evaluation of the left humerus, radius, and ulna demonstrated typical fibrous dysplasia as a cause for persistence of Ga-67 activity and shoulder activity probably representing arthropathy. She was in remission 3 years later although she fell and fractured the humerus through the bony lesion, and biopsy at the time of internal fixation confirmed fibrous dysplasia.

Giant colonic diverticulum

the imaging procedure of choice for diagnosis and followup. Gallium scanning and ACE measurement in serum and cerebrospinal fluid may be helpful but lack sensitivity and specificity. The same is true of increased protein and mild pleocytosis (usually lymphocytosis) in the cerebrospinal fluid. Definitive diagnosis of sarcoidosis requires biopsy evidence of non-caseating necrotizing granulomas.5 Hypothalamic-pituitary sarcoidosis is treated with corticosteroids together with anterior and posterior pituitary hormone replacement. Corticosteroids lower the CD4/CD8 lymphocyte ratio, decrease interleukin-2 production, and inhibit collagen synthesis, all of which are abnormal at the sites of active disease within the brain. When the dose of prednisolone is lowered to 20–25 mg daily the symptoms commonly recur. There are few data on other immunomodulatory therapies, but ciclosporin, radiotherapy, azathioprine, chlorambucil and cyclophosphamide have all been used with disappointing results.1 Surgical intervention is indicated in cases of hydrocephalus or when an expanding mass lesion causes an increase in intracranial pressure. Clearly, treatment of hypothalamic-pituitary sarcoidosis has made great advances since 1971, when the median survival was only 45 months.2 The patients reported here were two of only three diagnosed in our unit over that period. The third, a 26-year-old man, was seen in 1986 with panhypopituitarism. On replacement therapy he remains well 19 years later. Unfortunately the condition can still cause sudden unexpected death.6

Lymphomatous infiltration of the peripheral nervous system in enteropathy‐associated T‐cell lymphoma

Clinical record A 53-year-old woman with a 10-year history of coeliac disease controlled by a gluten-free diet presented with a 6-month history of dramatic weight loss and pyrexia. Physical examination showed wasting and peripheral oedema. Plasma albumin level was 23g/L (normal, 34-48 g/L). Computed tomography of head, neck, chest, abdomen and pelvis, gallium and positron emission tomography scans, liver biopsy and bone marrow biopsy were normal. The serum lactate dehydrogenase (LDH) level was 466 U/L (normal, 110-230 U/L), raising the possibility of occult malignancy, especially enteropathy-associated T-cell lymphoma (EATL). Endoscopic duodenal biopsy revealed mild increase in intraepithelial lymphocytes, crypt hyperplasia and villous abnormality in keeping with coeliac disease. Molecular clonality studies of the lymphoid cells in the duodenal biopsy yielded a monoclonal band of T-cell receptor (TCR) γ gene rearrangement in two separate series of biopsies taken 6 weeks apart. Refractory sprue was diagnosed, and the patient received sequential trials of prednisolone, cyclosporin A and infliximab without benefit. High dose cyclophosphamide (2 g/m 2 ) was administered 3 months later for presumed EATL. This resulted in immediate resolution of the fever and improved weight gain. The patient subsequently complained of paraesthesiae in her feet. Neurological examination was normal. Nerve conduction studies suggested an early axonal sensory peripheral neuropathy. Vitamin B 12 , folate, vitamin A-tocopherol, red blood cell transaminase and transketolase studies, vasculitic screen, glycated haemoglobin, syphilis serology and thyroid function tests were normal. Paraprotein was not detected in serum electrophoresis. Magnetic resonance imaging (MRI) of the brain showed non-specific patchy periventricular areas of high signal not suggestive of the suspected lymphoma. Her systemic symptoms of fever, sweats and weight loss responded to two further doses of cyclophosphamide (1 g/m 2 ), despite worsening neurological symptoms. After 3 months, the patient relapsed with recurrence of pyrexia, and the serum LDH level progressively rose to 838 U/L. Neuropathy progressed to the point where she could not walk. Reflexes were lost, with a glove-and-stocking pattern of sensorimotor disturbance. A repeated nerve conduction study confirmed severe axonal sensorimotor peripheral neuropathy affecting both upper and lower limbs. Cerebrospinal fluid was normal, and there were no malignant cells. Repeated investigations, including brain MRI and upper gastrointestinal endoscopy, did not reveal any further evidence of malignancy. A right sural nerve biopsy showed severe loss of myelinated nerve fibres, and many of the surviving fibres showed varying stages of axonal degeneration (Box 1) associated with a sparse, patchy endoneurial mononuclear cell infiltrate in some fascicles and prominent endoneurial fibrosis on trichrome stain. The CD45RB immunostain showed increased numbers of immunopositive endoneurial lymphoid cells that showed immunopositivity with the T-cell markers CD3 (Box 2) and CD5. The CD68 immunostain showed increased endoneurial macrophages, and ultrastructural assessment confirmed macrophage phagocytosis of degenerate myelinated fibres. CD20 immunostain was negative. The Congo red stain for amyloid was negative.

Sarcoidosis Demonstrated by FDG PET Imaging With Negative Findings on Gallium Scintigraphy

The manifestations of sarcoidosis are protean and have been well described. Conventionally, gallium-67 scan is used to evaluate sarcoidosis in nuclear medicine. Fluorodeoxyglucose positron emission tomography (FDG PET) has been successfully used in the evaluation of cancers. However, FDG is not a tumor-specific radiotracer and can also accumulate in the sarcoid lesions. We present a case of sarcoidosis, which demonstrated an unremarkable gallium-67 scintigraphy but showed extensive FDG uptake in the chest and the brain on PET imaging.

Primary Pyomyositis of Thigh: Report of Two Cases

Primary pyomyositis is an uncommon disorder in non-tropical climates and represents a unique diagnostic and therapeutic challenge to the clinician. A 26-year-old obese female and a 63-year-old male with poorly controlled diabetes mellitus, both suffered from painful unilateral thigh swelling for the previous 3 to 4 weeks. Fever, leukocytosis, and high inflammation indices were noted. The two patients had no recent history of trauma or surgery. Ultrasonography, magnetic resonance imaging, and a gallium-67 scan of the inflamed area revealed abscess formation on the anterior and lateral aspects of the thigh. Immediate incision and sequential debridements were performed. Overall, they were administered antibiotics for 6 to 7 weeks and recovered without any complications.

Lymphoma: Diagnosis, staging, natural history, and treatment strategies

Non-Hodgkin's lymphoma (NHL) is not a single disease, but a group of closely related B- and T-cell cancers of the lymphatic system. The incidence of NHL is rising, particularly in the countries of the industrialized world. The increased incidence is poorly understood, but several risk factors have been postulated to be associated with NHL, including: exposure to chemicals, viral infections, organ transplantation and blood transfusion, family history, and lifestyle factors. Precise staging of NHL is a prerequisite for the selection of a suitable therapeutic regimen and influences the likelihood of its success. Staging of lymphoma is traditionally conducted using tumor biopsy, imaging (X-ray, computerized tomography [CT], magnetic resonance imaging, lymphangiogram, gallium scan using 67 Ga citrate single photon emission CT [ 67 Ga-SPECT], or positron emission tomography), blood tests, bone marrow examination, and examination of cerebrospinal fluid. CT is the most commonly used imaging technique, but several studies indicate that other techniques, such as 67 Ga-SPECT, are more sensitive and better predictors of response. Low- and high-grade lymphomas differ markedly in prognosis and response to treatment. The management of NHL has been characterized by the increasing recognition that distinct subgroups of NHL respond differently to various therapeutic approaches. In follicular lymphoma (FL), a successful approach has been to combine fludarabine with mitoxantrone (FM), resulting in an overall response rate of 89% (67% complete remission). In an ongoing phase III trial in patients with untreated, advanced, low-grade follicular lymphoma, FM was compared with CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone) with or without rituximab. Patients previously treated with FM achieved a significantly better complete remission rate (67% v 38%; P = .0013) and a better molecular remission (36% v 20%; P = .049) than patients previously treated with CHOP. Following rituximab treatment, 88% of patients who had received FM achieved clinical and molecular remission compared with 70% who had received CHOP. Strategies using various chemotherapy combinations, including innovative agents such as 90 Y-ibritumomab tiuxetan, show promise in the treatment of NHL, particularly indolent NHL, and hopefully will lead to an improvement in prognosis.

Direct comparison of 18F‐fluorodeoxyglucose coincidence gamma camera tomography with gallium scanning for the staging of lymphoma

The present study compared the performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) using a coincidence dual-head gamma camera (FDG Co-PET) with 67gallium scinti graphy (GS) in pretreatment staging of lymphoma. A total of 46 patients underwent FDG Co-PET, computed tomography (CT) scanning and GS for pretreatment staging of lymphoma (40 newly diagnosed and recurrence) between November 1997 and December 1999. Histological subgroups comprised low grade (8 patients), intermediate grade (25) high-grade (3) non-Hodgkin's lymphoma and Hodgkin's disease (10). Based on clinical assessment, CT scan findings and biopsy, 100 nodal sites and 15 extra-nodal sites were deemed positive. FDG Co-PET was superior to GS in nodal site positivity rate (97%vs 79%, P < 0.0001). Compared with GS, FDG Co-PET detected 39 more abnormal sites in 22 patients (48%), of which 28 sites were validated by biopsy, CT and/or progress FDG Co-PET scanning. There was only one proven false negative FDG site in the spleen. CT + FDG Co-PET led to upstaging in 2 patients (4%), compared to CT + GS. FDG Co-PET shows potential for providing an accurate means for pretreatment staging of lymphoma and can detect extra sites of disease activity compared to GS.

Das Heerfordt-Syndrom ? eine seltene Erstmanifestation der Sarkoidose

Sarcoidosis is a chronic, multisystem disorder of unknown cause characterized by noncaseating epithelioid granulomas. Infectious agents and genetic components have been discussed. Heerfordt's syndrome with uveitis, enlargement of the parotid glands and optional paralysis of the Nn. facialis is a form of sarcoidosis. The diagnosis is confirmed by histology. Further analyses are fiberoptic bronchoscopy with bronchoalveolar lavage or the gallium-67 scan in combination with blood findings. The therapy of choice is glucocorticoids. We present a case report of Heerfordt's syndrome and a review of the literature covering different aspects of sarcoidosis.

Comparison of Animal Models with Soft Tissue Infection by Different Bacilli

In clinical medicine improved diagnostic methods for the detection of infection are needed. A good infectious animal model is very important for the development of a new diagnostic method or drug. The purpose of this study was to establish a good animal model with soft tissue infection. Twenty-four SD rats were divided into four groups (6 in each group). Various bacilli including Staphylococcus aureus (S. aureus), Streptococcus pneumoniae (S. pneumoniae), and Escherichia coli (E. coli) were injected intramuscularly into the left caudal thighs of three groups of rats to create soft tissue infection. In addition, normal saline was injected into the left caudal thighs of ten rats which were used as controls. Before and 48 hr after inoculation of the bacilli, a blood sample (0.5 ml) was taken from each rat and analyzed to determine the white blood cell count and differentiated cell count. In addition, 48 hr after the inoculation, 0.2 mCi of gallium-67 was injected via the tail vein. Gallium scan was performed at 24 hr and 48 hr after administration of the radiotracer. The dorsal view of both hind legs was imaged and analyzed by computers to calculate the lesion-to-normal (L/N) ratio. After imaging, all rats were sacrificed and specimens from portions of the infected thigh muscle were sent for histopathologic investigation to confirm the infection. The increase in both the WBC counts and the segmented polymorphonuclear leukocytes (PMNs) were most significant in the S. aureus group, followed by the S. pneumoniae group, E. coli group and normal control groups. The rats with S. aureus infection had significant gallium uptake at the site of infection and the highest L/N ratio of 2.14 on the 24-hr image and 2.0 on the 48-hr image. The rats with S. pneumoniae had the second highest L/N ratio (1.41 at 24 hr, and 1.48 at 48 hr). The L/N ratio for the E. coli group was 1.27 at 24 hr and 1.35 at 48 hr. No obviously abnormal gallium uptake was demonstrated in the normal controls. We conclude that all three bacilli induced a soft tissue infection in SD rats. S. aureus resulted in the most significant infectious signs.