Pan-Fu Kao

Diagnosis and treatment of pyogenic psoas abscess in diabetic patients: usefulness of computed tomography and gallium-67 scanning

OBJECTIVES To examine retrospectively the clinical presentations, microbiologic characteristics, and treatment outcomes of psoas abscess in patients with diabetes mellitus (DM) and to assess the usefulness of computed tomography and gallium-67 scanning in its early diagnosis. METHODS During a 9-year period, psoas abscesses in patients with DM were collected at a medical center. The clinical history and associated etiologic factors, microbiologic results, clinical outcomes, and hospitalization days were recorded. The use of imaging in the diagnosis of psoas abscess and other concomitant infectious lesions was also studied. RESULTS Fifteen patients with DM and psoas abscess (13 women and 2 men; mean age 58.7 +/- 9.0 years) were found. The most frequent symptom was fever (12 of 15). Of the six different microorganisms that grew in the blood and/or abscess cultures, Staphylococcus aureus was the most frequent (7 of 15). The most commonly associated pathologic finding was vertebral osteomyelitis (5 of 15). Computed tomography and/or magnetic resonance imaging confirmed the diagnosis of psoas abscesses in all 15 patients. The gallium-67 scan especially aided in the diagnosis of the patients who had initially been diagnosed as having fever of unknown origin (4 of 5) and in the diagnosis of concomitant lesions (9 of 12). Debridement or surgical drainage of the abscess was done in 12 patients. All the patients received adequate antibiotic treatment. However, the mortality rate was 20%. The average hospitalization stay was 42.7 +/- 20.7 days. CONCLUSIONS Psoas abscess in patients with DM is a disease with both diagnostic and therapeutic challenges. We found the infecting microorganisms to be variable and the mortality rate high.

The optimal imaging time for [99Tcm]TRODAT-1/SPET in normal subjects and patients with Parkinson's disease.

Imaging of dopamine transporters (DATs) in the brain using [99Tcm]TRODAT-1 showed excellent pharmacokinetics for estimation of transporter concentrations. It has been reported that there may be differences in the binding kinetics of DAT radiotracers to DATs between normal subjects and patients with Parkinsons disease (PD). The aim of this study was to determine an optimal time point for [99Tcm]TRODAT-1 brain single photon emission tomography (SPET) acquisition that provides stable target to non-target ratios reflecting the DAT concentration in the brain. Serial [99Tcm]TRODAT-1 brain SPET images 2, 3 and 4 h after intravenous injection of [99Tcm]TRODAT-1 (925 MBq) were performed in five healthy subjects and nine PD patients. Regions of interests were drawn, and caudate/occipital (C/O) and putamen/occipital (P/O) specific to non-specific [99Tcm]TRODAT-1 binding ratios were calculated. The C/O and P/O ratios in healthy subjects showed consistent increases with time, but in PD patients, the C/O and P/O ratios of [99Tcm]TRODAT-1 reached a stable level at 3 h post-injection. There was a statistically significant difference (P<0.001) between PD and normal subjects at 4 h post-injection for both the C/O and the P/O ratios. In conclusion, we recommend the acquisition of [99Tcm]TRODAT-1 SPET images at 4 h post-injection, as at this time point the C/O and P/O ratios can be used to discriminate between PD patients and healthy subjects.

The impact of image fusion in resolving discrepant findings between FDG-PET and MRI/CT in patients with gynaecological cancers

This study was performed to prospectively investigate the impact of image fusion in resolving discrepant findings between fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) or X-ray computed tomography (CT) in patients with gynaecological cancers. Discrepant findings were defined as lesions where the difference between the FDG-PET and MRI/CT images was assigned a value of at least 2 on a 5-point probability scale. The FDG-PET and MRI/CT images were taken within 1 month of each other. Image fusion between FDG-PET and CT was performed by automatic registration between the two images. During an 18-month period, 34 malignant lesions and seven benign lesions from 32 patients who had undergone either surgical excision or a CT-guided histopathological investigation were included for analysis. Among these cases, image fusion was most frequently required to determine the nature and/or the extent of abdominal and pelvic lesions (28/41, 68%), especially as regards peritoneal seeding (8/41, 20%). Image fusion was most useful in providing better localisation for biopsy (16/41, 39%) and in discriminating between lesions with pathological versus physiological FDG uptake (12/41, 29%). Image fusion changed the original diagnosis based on MRI/CT alone in 9/41 lesions (22%), and the original diagnosis based on FDG-PET alone in 5/41 lesions (12%). It led to alteration of treatment planning (surgery or radiotherapy) in seven of the 32 patients (22%). In patients with gynaecological cancers, the technique of image fusion is helpful in discriminating the nature of FDG-avid lesions, in effectively localising lesions for CT-guided biopsy and in providing better surgical or radiotherapy planning.

99Tcm-MDP scintigraphy in high-voltage electrical burn patients

In high-voltage electrical burn injuries ( > 1000 V), it is difficult to identify the site and extent of non-viable deep tissue damage for debridement to avoid further tissue injury from wound infection and the risk of sepsis. This prospective study was designed to evaluate the usefulness of 99Tcm-methylene diphosphonate (99Tcm-MDP) scintigraphy in detecting the extent of tissue injury and determining the level of amputation required for electrical burn patients. Over a 5 year period, 33 high-voltage electrical burn patients were studied. Blood flow and blood pool studies revealed absent perfusion in 37 limbs, all of which eventually were amputated. In addition to a routine three-phase bone scan, images were obtained at 30–60 min (early images) to evaluate whether soft tissue injury could be detected better at that time. For comparison of the detection rate from the early images and bone (delayed) images, 164 corresponding spot views of both images were reviewed. Eighty-three and 125 tissue necrotic lesions were demonstrated by the early images and bone images respectively. All of the 83 lesions found by the early images were more clearly identified by the bone images. All but one of the 125 lesions underwent surgical debridement or amputation. We concluded that the blood flow and blood pool images correlated well with the level of amputation required. The site and extent of tissue necrotic lesions can be clearly identified on 99Tcm-MDP bone scans. Because the early images were less sensitive in detecting tissue necrosis, we suggest that early imaging is not necessary.

Obstructive hydronephrosis with I-131 MIBG accumulation mimicking huge pheochromocytoma: a diagnostic pitfall found with Tc-99m MDP imaging.

A case of severe obstructive hydronephrosis, which caused a false-positive I-131 MIBG scan for detection of a pheochromocytoma is reported. A huge area of persistent I-131 MIBG accumulation 72 hours after injection in the left flank region was suspected to be a huge pheochromocytoma. Combined studies with I-131 MIBG, Tc-99m MDP, Tc-99m DMSA, and Tc-99m DTPA as well as furosemide injection disclosed that the abnormal 1-131 MIBG accumulation was caused by left obstructive hydronephrosis. The result was finally confirmed by intravenous pyelography and CT studies.

The role of 67Ga in the early detection of spinal epidural abscesses.

In this study, we evaluated the role of 67Ga whole-body and single photon emission tomographic (SPET) imaging in the early diagnosis and lesion localization of spinal epidural abscess before confirmation by gadolinium-enhanced magnetic resonance imaging (MRI). Six patients with fever of unknown origin had a 67Ga whole-body scan, four of whom also underwent SPET imaging. For further confirmation of a spinal epidural abscess, gadolinium-enhanced MRI was performed in all patients. All patients had increased 67Ga uptake in a spinal or paraspinal area on the whole-body scan. They were later confirmed to have a spinal epidural abscess after gadolinium-enhanced MRI. Of these six patients, five underwent surgical drainage plus parenterally administered antibiotics, and had complete or partial recovery. One died before operation due to sepsis. In conclusion, we suggest performing a 67Ga whole-body survey as early as possible in patients with fever of unknown origin, fever and back pain and/or the spinal syndrome, before MRI is performed. If a spinal epidural abscess is strongly suspected, SPET is needed for further confirmation of spinal versus non-spinal and contiguous versus non-contiguous lesion(s). If MRI is unavailable, then 67Ga scintigraphy is a satisfactory method for investigating spinal epidural abscesses.

Gallium-67 Scanning in Endogenous Klebsiella endophthalmitis with Unknown Primary Focus

A whole-body gallium-67 (Ga-67) scan of a 61-y-old male with diabetes mellitus who suffered from endogenous Klebsiella endophthalmitis is reported. The scan revealed right orbital and lower abdominal lesions. Urinary analysis revealed pyuria. The causes of endogenous Klebsiella endophthalmitis and the usefulness of Ga-67 are discussed.A whole-body gallium-67 (Ga-67) scan of a 61-y-old male with diabetes mellitus who suffered from endogenous Klebsiella endophthalmitis is reported. The scan revealed right orbital and lower abdominal lesions. Urinary analysis revealed pyuria. The causes of endogenous Klebsiella endophthalmitis and the usefulness of Ga-67 are discussed.

The clinical significance of gall-bladder non-visualization in cholescintigraphy of patients with choledochal cysts

Intravenous radionuclide cholescintigraphy (IVRC) provides a very specific picture for choledochal cysts. However, the clinical significance of the non-visualization of the gall-bladder (GB) activity in these cases is unclear. In this study, we reviewed 27 patients with choledochal cysts who underwent IVRC within 7 days prior to operation and correlated the GB findings on IVRC with the histopathological results. In 18 of the 27 patients (66.7%), there was non-visualization of the GB at 4 h post injection. Among these, two had histopathological features of acute cholecystitis (AC), 11 had chronic cholecystitis (CC), and five had normal GBs. In the other nine patients with visualization of the GB, there were five cases of CC and four normal GBs. If we apply the finding of non-visualization of the GB at 4 h post injection as the criterion for the diagnosis of AC, the diagnostic accuracy was only 40.7% (11/27). We concluded that: (1) GB disease (AC and CC) was common (66.7%: 7.4% and 59.3% respectively) in choledochal cyst patients. (2) Non-visualization of the GB on IVRC did not necessarily indicate AC in choledochal cyst cases, and the diagnostic accuracy was low. (3) GB disease is not the only cause of GB non-visualization on IVRC. A huge choledochal cyst causing a mass or reservoir effect may be a cause of GB compression and result in non-visualization of the GB.

Accumulation of Ga-67 citrate in a tuberculous splenic abscess : report of a rare case

A case of 65-year-old man with tuberculous splenic abscess is presented. The Ga-67 citrate scan revealed three focal areas of increased uptake in the left upper quadrant of the abdomen. The combined Tc-99m SC/Ga-67 scans revealed that these Ga-67 avid lesions localized in the splenic photon-deficit areas found in the Tc-99m SC scan. This case demonstrated the usefulness of Ga-67 imaging in a survey of fever of unknown origin in unsuspected tuberculous splenic abscess.

Lymphoscintigraphy and intraoperative gamma probe-directed sentinel lymph node mapping in patients with malignant melanoma.

BACKGROUND AND PURPOSE Lymphoscintigraphy has been considered a useful tool for sentinel lymph node (SLN) mapping for malignant melanoma. This study evaluated the usefulness of SLN detection by lymphoscintigraphy and excision with intraoperative gamma probe in Taiwanese patients with malignant melanoma. METHODS Thirty six malignant melanoma patients in clinical stage I and II were enrolled. The Breslow thickness of the primary melanomas was </= 1.0 mm in 8 patients, 1.01 to 2.0 mm in 12 patients, 2.01 to 4.0 mm in 9 patients, >/= 4 mm in 3 patients, and unknown in 4 patients who were transferred from other hospitals and had no nodal or distant metastasis. SLN lymphoscintigraphy was performed with filtered 99mTc-sulfur colloid. An intraoperative gamma probe was used to identify the SLN for dissection. RESULTS A total of 44 SLNs were detected in 36 patients, with a mean of 1.22 SLNs per patient. The SLN detection rate by lymphoscintigraphy was 100%. During surgery, 39 of the 44 SLNs (88.6%) in 33 of 36 patients (91.7%) were identified. SLN metastasis was found in 8 of 39 dissected SLNs (20.5%) or in 8 of 36 patients (22.2%). The SLN metastatic rate in the patients with primary melanoma with Breslow thickness </= 2.0 mm was 10.0% (2/20), and in patients with Breslow thickness > 2.0 mm was 41.7% (5/12). CONCLUSIONS Lymphoscintigraphy and intraoperative gamma probe are useful in localizing and dissecting SLN in patients with malignant melanoma. SLN mapping changed the clinical stage in 22.2% of melanoma patients.