Roberta Doria

Added Value of 99mTc-HMPAO–Labeled Leukocyte SPECT/CT in the Characterization and Management of Patients with Infectious Endocarditis

The clinical performance of the Duke Endocarditis Service criteria to establish the diagnosis of infectious endocarditis (IE) can be improved through functional imaging procedures such as radiolabeled leukocytes (99mTc-hexamethylpropyleneamine oxime [HMPAO]–labeled white blood cells [WBC]). Methods: We assessed the value of 99mTc-HMPAO-WBC scintigraphy including SPECT/CT acquisitions in a series of 131 consecutive patients with suspected IE. Patients with permanent cardiac devices were excluded. 99mTc-HMPAO-WBC scintigraphy results were correlated with transthoracic or transesophageal echocardiography, blood cultures, and the Duke criteria. Results: Scintigraphy was true-positive in 46 of 51 and false-negative in 5 of 51 cases (90% sensitivity, 94% negative predictive value, and 100% specificity and positive predictive value). No false-positive results were found, even in patients with early IE evaluated within the first 2 mo from the surgical procedure. In 24 of 51 patients with IE, we also found extracardiac uptake, indicating septic embolism in 21 of 24. Despite the fact that septic embolism was found in 11 of 18 cases of Duke-definite IE, most of the added value from the 99mTc-HMPAO-WBC scan for decision making was seen in patients in whom the Duke criteria yielded possible IE. The scan was particularly valuable in patients with negative or difficult-to-interpret echocardiographic findings because it correctly classified 11 of 88 of these patients as having IE. Furthermore, 3 patients were falsely positive at echocardiography but correctly negative at 99mTc-HMPAO-WBC scintigraphy: these patients had marantic vegetations. Conclusion: Our results demonstrate the ability of 99mTc-HMPAO-WBC scintigraphy to reduce the rate of misdiagnosed cases of IE when combined with standard diagnostic tests in several situations: when clinical suspicion is high but echocardiographic findings are inconclusive; when there is a need for differential diagnosis between septic and sterile vegetations detected at echocardiography; when echocardiographic, laboratory, and clinical data are contradictory; and when valve involvement (especially of a prosthetic valve) needs to be excluded during febrile episodes, sepsis, or postsurgical infections.

Scintigraphic imaging of vertebral osteomyelitis with 111in-biotin.

Study Design. Early diagnosis of vertebral infection (hematogenous or postsurgical) is necessary to choose a correct therapy and to minimize dramatic complications. All patients suspected to have vertebral infection underwent radiologic imaging and 111In-Biotin scintigraphy. Objective. Biotin is a growth factor used by many bacteria. The aim of our study is to use 111In-Biotin to diagnose vertebral infections. Summary of Background Data. Magnetic resonance imaging, even if endowed with fairly good sensitivity and specificity, shows some limitations in the study of the onset of pathology and in postsurgical conditions. Conventional scintigraphic imaging, like bone scintigraphy with 99mTc-MDP, 67Ga-citrate scintigraphy, or Positron Emission Tomography with [18F]FDG, are limited by relatively low specificity; the use of Streptavidin/111In-Biotin scintigraphy, based on aspecific uptake of tracer in the site of infection, shows good results in term of sensibility and specificity but the use of heterologous protein might engender immunogenic reactions. Methods. All patients (pts) (n = 110) of the study underwent 111In-biotin scintigraphy 2 hours after intravenous injection of the tracer, 71 pts were suspected to have hematogenous vertebral infection (Group I) and 39 pts were suspected to have postsurgical infection (Group II). The reference for final diagnosis was either bacterial cultures, histopathologic analysis, and/or clinical/imaging follow-up for at least 1 year. Results. 111In-biotin scintigraphy showed a sensitivity of 84% and specificity of 98% in Group I and a sensitivity of 100% and specificity of 84% in Group II. Conclusion. Our results showed that 111In-Biotin scintigraphy possess high diagnostic accuracy. This technique is easy to perform and requires short imaging time-point after intravenous tracer injection. Moreover if 111In-Biotin uptake is due only to high proliferation rate of bacteria presents in site of infection, it will be further investigated to discriminate definitely bacterial from sterile inflammation.

Fever, mental impairment, acute anemia, and renal failure in patient undergoing orthotopic liver transplantation: Posttransplantation malaria

A case of post‐transplant malaria is described. The patient presented fever and severe anemia after orthotopic liver transplantation. Diagnosis was made only after the review of donor characteristics. Although a high parasitemia was found at the moment of diagnosis, the treatment with quinine and doxycycline was successful. Donor epidemiology should always be considered for a prompt diagnosis of rare tropical diseases in the graft recipients. Liver Transpl 12:674–676, 2006.

Clinical impact of SPECT/CT with In-111 biotin on the management of patients with suspected spine infection.

Purpose: Early identification and localization of spine infection is necessary for adequate therapeutic strategy. To localize the precise site of infection we evaluated In-111 Biotin SPECT/CT versus planar and SPECT imaging. Methods: Seventy-two consecutive patients were enrolled and underwent SPECT/CT and planar imaging 2 to 4 hours post i.v. injection of In-111 Biotin. Final diagnosis was based on bacterial cultures and/or clinical/imaging follow-up for at least 1 year. We evaluated the diagnostic performance of planar, SPECT, and SPECT/CT In-111 Biotin scintigraphy. Results: In-111 Biotin SPECT/CT and SPECT showed similar values of sensitivity (93.5% vs. 92.1%) and the same specificity (92.3%), planar imaging showed 80.4% of sensitivity and 69.2% of specificity. In 16 patients SPECT/CT correctly localized the infection site (bone, soft tissue, or both bone and soft tissue). Conclusions: SPECT/CT enhances the impact of In-111 Biotin scintigraphy on the clinical management of patients, allowing the exact site of infection to be localized to select the appropriate therapy.

Linezolid for endocarditis: a case series of 14 patients

Response of MRSA and MSSA endocarditis was 2/3 (67%) and 4/5 (80%), respectively. All other cases were cured: one VRE; three MRSE; and two cases of polymicrobial endocarditis. Response of native valve endocarditis was 7/8 (87.5%) and that of prosthetic valve endocarditis was 2/2 (100%). In three out of four patients with PM endocarditis (75%), the removal of the PM combined with antibiotic therapy, linezolid monotherapy in one case, was able to heal the infection. In these three patients, PM culture was still positive for the same S. epidermidis strain as isolated from the blood, probably due to the inactivity of linezolid against slime-producing bacteria. 4 Therefore, for PM endocarditis, linezolid may be an option only if the entire device is removed. Patients were followed up for at least 6 months, and no relapses were recorded.

A case of endocarditis with cerebral embolism successfully treated with daptomycin

A young girl was admitted for fever, headache, paresthesia of the hands, involuntary blinking of the left eye and aphasia. Imaging revealed mycotic cerebral aneurysms and finally infective endocarditis was diagnosed and successfully treated with daptomycin. She had a history of mitral prolapse and she had undergone dental procedures some months before without any antibiotic prophylaxis, according to the 2007 guidelines of the American Heart Association.