The use of radionuclide cisternography in the diagnosis of pleural cerebrospinal fluid fistulae.

Radionuclide cisternography (RNC) is an excellent method of studying cerebrospinal fluid (CSF) dynamics and fistulous communications. Two patients are described in which pleural cerebrospinal fluid fistulae were found by this technique. In addition, marking the area presurgically reduced operating room time in one patient. Such communications are important to locate since they can cause significant loss of CSF as well as provide a pathway for pathogens to enter the central nervous system.

Right aortic arch: demonstration by first-pass and multigated radionuclide ventriculography.

Right aortic arch is a rare congenital anomaly associated with abnormal development of the paired embryological aortic arches. While various abnormalities of the great vessels have been described using both first-pass and multigated radionuclide ventriculographic studies, diagnosis of a right-sided aortic arch has typically required a radiographic contrast technique. We present a case of a patient with a suspected right-sided aortic arch diagnosed by radionuclide methods.

Enterogastric bile reflux during technetium-99m-sestamibi cardiac imaging.

UNLABELLED: Enterogastric bile reflux (EGBR), a risk factor for both gastritis and esophagitis, is a potentially treatable noncoronary cause for chest pain. METHODS: To investigate the frequency of EGBR during different 99mTc-sestamibi cardiac imaging, 1405 consecutive 99mTc-sestamibi SPECT myocardial perfusion studies were reviewed. RESULTS: One hundred sixteen of the 1405 patient studies (8.3%) showed EGBR with roughly equal numbers of patients having marked (43 patients), moderate (38 patients) or minimal (35 patients) intensity of abnormal gastric activity. Two examinations showed gastroesophageal reflux of activity. EGBR was less frequent with treadmill stress testing (5.5% patients) than with pharmacologic stress testing using either dipyridamole (11% of patients) or dobutamine (9.2% of patients) (p > 0.005). EGBR also was more frequent in patients over 40 yr of age. Finally, the prevalence of upper gastrointestinal symptoms and the frequency of established upper gastrointestinal diagnoses correlated strongly with the presence and intensity of EGBR. CONCLUSION: Clarification of the full clinical significance of EGBR during 99mTc-sestamibi cardiac imaging is a topic for future research. Nonetheless, the imaging finding of EGBR may, in fact, identify a potentially treatable noncoronary cause for chest pain.

Comparison of high-resolution MRI and SPECT bone scintigraphy for noninvasive imaging of the temporomandibular joint.

Prospective evaluation by magnetic resonance imaging (MRI) and both single photon emission computed tomography (SPECT) and planar bone scintigraphy was undertaken in 31 temporomandibular joints (TMJs) of 21 symptomatic patients. When compared with the results of subsequent arthrography, MRI (0.88) was more sensitive than SPECT (0.76) or planar (0.56) scintigraphy for detection of internal derangement of the TMJ. A diagnostic sensitivity of 0.96 was achieved when the results of either MRI or SPECT was considered evidence of internal joint derangement. Five symptomatic TMJs, clinically thought to be abnormal, were positive on SPECT but showed no evidence of anterior disk displacement at the time of arthrography. In such instances, SPECT may be detecting functionally significant altered joint mechanics that are not evident on anatomic imaging of the TMJ.

Comparison of technetium-99m pyrophosphate and technetium-99m DTPA aerosols for SPECT ventilation lung imaging.

Although [99mTc] diethylenetriaminepentaacetic acid (DTPA) is currently the most widely used radioaerosol, rapid alveolar clearance limits its usefulness for single photon emission computed tomography (SPECT) ventilation lung imaging. Previous research has shown that [99mTc]phosphate compounds have high alveolar deposition and slow clearance and thus provide suitable aerosols for pulmonary ventilation studies. We have compared the pulmonary retention and blood levels of [99mTc]pyrophosphate (PYP) and [99mTc]DTPA in eight normal nonsmoking male volunteers. These two radioaerosols have comparable pulmonary deposition. Technetium-99m PYP, however, has a much slower pulmonary clearance which allows sufficient time (20 or more minutes) for SPECT data acquisition using a single-headed rotating gamma camera. While the radiation absorbed dose to the lungs for [99mTc]PYP (0.31 rad/mCi) is greater than for [99mTc]DTPA (0.11 rad/mCi), it is at a clinically acceptable and safe level.

Bone SPECT.

Single photon emission computed tomography (SPECT) is a valuable addition to bone scintigraphy. SPECT removes from the diagnostic image unwanted activity which originates from in front and behind the tomographic plane of medical interest. This tomographic procedure allows one to examine with greater contrast and anatomic clarity such structures as the spine, hips, knees, and temporomandibular joints (TMJ). Abnormalities also seen on planar bone scintigrams often are more convincingly identified and better localized by SPECT. SPECT may even detect skeletal abnormalities not evident on planar views. These advantages of SPECT must be weighed against the superior resolution of planar bone scintigraphy. For this reason, SPECT complements, but does not replace planar bone scintigraphy. Including SPECT as an additional component of the skeletal examination does not place excessive demands on either gamma camera use or technologist time. Those nuclear medicine facilities offering bone SPECT for the evaluation of back, hip, knee, and TMJ pain should anticipate a larger volume of patient referrals.

Diagnostic bone scanning in oncology.

Over the last several decades bone scanning has been used extensively in the evaluation of oncology patients to detect bone involvement. It can provide information about disease location, prognosis, and the effect of therapy. Bone scanning offers the advantages of whole body evaluation and the detection of lesions earlier than other techniques. However, as newer diagnostic tools become available, indications for bone scanning must be revised and the results combined with these other tests in order to provide optimum patient care. Advances in instrumentation and the subsequent improvement in image quality have allowed nuclear medicine physicians to provide more accurate bone scan interpretations. By optimizing image acquisition, it is often possible to determine lesion characteristics, which are more likely to represent malignancy. Knowledge of disease pathophysiology and other specific properties of the patient's primary tumor, along with subsequent correlation of scan abnormalities to patient history, physical examination, previous studies, and other radiological examinations, is essential for determining lesion significance. The differential diagnosis of a scan abnormality should also include consideration of both false normal and abnormal causes. The final interpretation should be clearly communicated to the clinician with appropriate recommendations for further evaluation. Only through careful attention to the patient, the clinician, and appropriate study acquisition parameters will bone scanning maintain its place in the evaluation of oncology patients.

Evaluation of 99Tc(m)-ECD as a white blood cell labelling agent.

99Tc(m)-ECD is a new agent for perfusion brain imaging. Its brain retention is attributed to the enzymatic conversion of lipophilic 99Tc(m)-ECD to polar monoacid and diacid derivatives. Based on its proposed mechanism of retention in the brain, labelling of white blood cells (WBC) with 99Tc(m)-ECD has been studied at our laboratory. A labelling efficiency of 42% was achieved by incubating WBC with 99Tc(m)-ECD in phosphate buffered saline medium for 30 min. There was a washout of 50% of the radioactivity from the cells in 1 h, which might contribute to increased background in potential human studies. However, rapid urinary elimination of the radioactivity is expected to deal with this problem due to the rapid in vivo conversion of the parent compound to polar metabolites. 99Tc(m)-ECD appears to be a promising agent for labelling WBC. Furthermore, already prepared multidose 99Tc(m)-ECD may be used for either brain perfusion imaging or WBC labelling.

A high-efficiency, rapid and multi-dose procedure for white blood cell labelling with 99Tcm-HMPAO.

99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO) is presently recognized as an effective radiopharmaceutical for in vitro white blood cell (WBC) labelling in addition to its widespread utility in cerebral blood flow imaging. While performing clinical studies in patients with a wide range of inflammatory diseases, the effect of the ligand and stannous ion quantity on the labelling efficiency (LE) of WBC was examined. A mean LE of 64 +/- 7% (n = 29) was achieved when the whole HMPAO kit was used for labelling. The LEs were 78 +/- 5% (n = 43), 83 +/- 3% (n = 37) and 85 +/- 5% (n = 18) when one-half, one-third and one-fifth of the lyophilized kit was used, respectively. This is in agreement with the reports of Sampson et al. and Lang et al., suggesting that the optimal formulation of the 99Tcm-HMPAO is a faction of the whole kit. Accordingly, fractionation of a freshly prepared 99Tcm-HMPAO kit into five parts for a high-efficiency WBC labelling is proposed, encouraging the more widespread use of 99Tcm-HMPAO in WBC labelling.

Evaluation of 99Tcm-bicisate as a renal imaging agent.

99Tcm-bicisate (99Tcm-ECD), often used as a brain perfusion agent, is rapidly converted following intravenous injection to the polar monoacid (99Tcm-ECM) and diacid (99Tcm-EC) metabolites. Such polar metabolites, which are eliminated principally by renal clearance, are potential renal imaging agents. In this study, 99Tcm-ECD was compared for the first time with 99Tcm-EC, 99Tcm-mercaptoacetyltriglycine (99Tcm-MAG3) and 131I-orthoiodohippurate (OIH) as renal imaging agents in rabbits. Whole-body images and renograms were obtained for all three of the 99Tcm agents, and pharmacokinetic parameters including plasma and urinary clearance were studied for all four agents. The plasma clearance of 99Tcm-EC (37 ml min-1) was slower than that of 99Tcm-ECD (51 ml min-1), which could be accounted for by the higher liver uptake of 99Tcm-ECD. The urinary clearance of 99Tcm-ECD (35 ml min-1), 99Tcm-EC (34 ml min-1) and 99Tcm-MAG3 (39 ml min-1) was similar. The renal images obtained with 99Tcm-ECD were comparable to those for 99Tcm-MAG3 and 99Tcm-EC. However, liver uptake was more prominent with 99Tcm-ECD than with the other agents. The 99Tcm-ECD renogram curves showed a prolonged decrease in renal activity compared to both 99Tcm-EC and 99Tcm-MAG3. In potential human studies, the relatively high liver uptake of 99Tcm-ECD superimposed on right renal activity may be a limitation. Therefore, we conclude that 99Tcm-ECD is less favourable when compared to existing renal agents due to its high extrarenal uptake and renal kinetics.

Biodistribution of 99Tcm-labelled 5-thio-D-glucose.

We studied the biodistribution and tumour localization of 99Tcm-labelled-5-thio-D-glucose (99Tcm-TG). 5-Thio-D-glucose was labelled with 99Tcm by direct stannous ion reduction. The biodistribution of 99Tcm-TG was investigated in normal rabbits and in mice bearing experimental tumours. In rabbits, the plasma and clearance of 99Tcm-TG was 14.5 +/- 2.0 and 11.3 +/- 3.0 ml.min-1 respectively. Urinary excretion at 1 h was 53 +/- 5%. 99Tcm-TG was injected intravenously in mice bearing MC26 colon carcinoma and tissue samples were analysed by gamma scintillation counting at various times. Uptake of 99Tcm-TG in tumour at 1 and 3 h was 1.6 +/- 0.3% and 1.2 +/- 0.3%; the tumour to muscle ratios were 2.7:1 and 4:1 respectively. The autoradiographic biodistribution of 99Tcm-TG in MX-1 human breast xenografted nude mice showed more persistent tumour uptake of 99Tcm-TG than 14C-2-deoxyglucose (14C-DG). 99Tcm-TG accumulated in the centre of the tumours; 14C-DG was decreased in this central region probably because of zones of infarction on necrosis. The discordance between the tumour uptake of 99Tcm-TG and 14C-DG indicates that 99Tcm-TG does not act like a glucose analog, suggesting 99Tcm-TG avidity for zones of infarction or necrosis. The further study of 99Tcm-TG in tumours and ischaemic injury is warranted.

SPET and three-phase planar bone scintigraphy in adult patients with chronic low back pain.

Among adults, low back pain (LBP) persisting for more than 3 months is a common complaint. A variety of imaging modalities including bone scintigraphy have been recommended as appropriate for the investigation of chronic LBP, even when there is no reason to suspect that the pain is due to tumour, infection or inflammatory arthritis. In this chronic LBP population, the diagnostic benefit of bone SPET, together with planar flow study, blood pool and delayed three-phase imaging, was assessed, Altogether, 2108 consecutive adult patients were entered into the chronic LBP bone scintigraphy database. Retrospective exclusion of patients with a history of tumour, infection or inflammatory arthritis reduced the population to 1390, of whom 916 underwent a lumbosacral spine flow study and blood pool imaging in addition to planar and SPET bone scintigraphy. The diagnostic benefit of these imaging studies was tabulated and compared. In addition, a retrospective chart review of the patients with renal and other soft tissue abnormalities identified by a flow study and blood pool imaging was undertaken with a view to documenting any changes in treatment planning over the 6 months following the nuclear medicine studies. Of the lumbosacral spine abnormalities, 44.1% were seen equally well on planar and SPET images, 24.0% better on SPET, 31.4% only seen on SPET, and 0.4% only seen on planar imaging. The distribution of abnormalities identified on SPET images in the lumbar spine was divided between vertebral bodies (36.1%), lamina or pedicles (which included frequent sites of increased uptake in the articular facets and pars interarticularis) (53.8%), spinous processes (8.7%) and transverse processes (1.3%). For the flow study and blood pool imaging, there was a 16.7% rate of positive studies. However, there were no documented changes in treatment planning because of these positive findings. In conclusion, when used to examine adult patients with chronic LBP, SPET detects significantly more scintigraphic abnormalities than planar imaging. The addition of a flow study and blood pool imaging as part of these LBP examinations results in a significant benefit. However, the clinical utility of such flow study and blood pool imaging studies cannot be confirmed.

Radionuclide therapy for palliation of pain due to osteoblastic metastases.

Beta-emitting, bone-seeking radiopharmaceuticals, administered systemically, represent a good alternative or adjuvant to external beam radiotherapy for palliation of painful osteoblastic bone metastases. The most frequently used radiopharmaceutical for this purpose is strontium 89, followed by samarium 153 ethylenediaminetetramethylene phosphonate, and infrequently phosphorus 32 orthophosphate. Prior to consideration for radionuclide therapy, recent bone scans should be evaluated in order to determine if the patient has painful osteoblastic lesions likely to respond to therapy. Approximately 70% of patients with prostate and breast cancer will have a reduction in pain in response to radionuclide therapy, beginning within 2 to 4 weeks and lasting between 2 and 6 months. Patients who are expected to live 3 or more months are more likely to benefit than patients with shorter duration life expectancy. Hematosuppression is the chief side effect of radionuclide therapy, with leukopenia and thrombocytopenia more likely to be clinically significant than anemia. Relative contraindications for treatment include osteolytic lesions, pending spinal cord compression or pathologic fracture, preexisting severe myelosuppression, urinary incontinence, inability to follow radiation safety precautions, and severe renal insufficiency.

False-negative bone imaging due to etidronate disodium therapy.

A 77-year-old man with prostate cancer was serially evaluated for bone metastases using Tc-99m methylene disphosphonate (Tc-99m MDP) both on and off treatment with etidronate disodium (EHDP). While the patient was receiving the medication only minimal bony uptake of the tracer was seen with the majority remaining in the soft tissues. The similarly structured EHDP probably saturated the binding sites that the radioactive MDP usually adheres to. Physicians should be aware of this interaction and may have to wait until the EHDP has been discontinued for several months before performing bone imaging on these patients.

Flow study and SPECT imaging for the diagnosis of giant cell tumor of bone.

A case of giant cell tumor of bone is reported in which the blood flow study along with SPECT imaging improved the visualization and diagnosis of the abnormality.

Pulmonary embolism as an indicator of occult malignancy.

A case that demonstrates the relationship between malignancy and pulmonary throboembolic disease is presented. Pulmonary embolism, which was diagnosed on a ventilation-perfusion lung scan, initiated a search for the etiology of this condition. Normal examination of the deep venous system of the legs prompted further investigation, which ultimately led to the endoscopic diagnosis of poorly differentiated gastric carcinoma.

Concentration of Tc-99m MDP in ovarian carcinoma and its soft tissue metastases.

A patient with ovarian carcinoma was evaluated for skeletal metastasis with a routine whole body bone scan. Although no bone metastases were visualized, there was dramatic accumulation of tracer in the soft tissues of the abdomen. CT revealed calcifying soft tissue metastases on the liver surface, the bowel serosa, and in the pelvis corresponding to the abnormal areas of Tc-99m MDP uptake. Tumor necrosis and ongoing calcification within the metastatic sites are possible explanations for this unusual soft tissue concentration of the bone-seeking radiopharmaceutical. In patients with metastatic ovarian carcinoma, careful review of extraosseous regions on bone scan images may provide valuable diagnostic information.

Diagnostic reliability of radionuclide ventriculography in detecting left ventricular hypertrophy. Echocardiographic and ECG correlations.

Left ventricular hypertrophy (LVH) is frequently present in patients referred for radionuclide ventriculography (RVG) for evaluation of left ventricular function. During interpretation of these studies, the nuclear medicine physician may have the subjective impression that increased septal thickening is present because of the abnormally prominent separation of the right and left ventricular blood pools. To examine the diagnostic reliability of this finding, we retrospectively reviewed the RVG studies of 43 consecutive patients and correlated the finding of subjectively increased septal thickness with established echocardiographic (ECHO) criteria and commonly used electrocardiographic (ECG) indices of LVH. Using standard ECHO measurements of septal thickness as a gold standard, RVG interpretation of septal thickening demonstrated a sensitivity of 0.69, specificity of 0.70, and accuracy of 0.70. When compared with standard ECG criteria for LVH, RVG performed quite favorably in the diagnosis of LVH confirmed by ECHO left ventricular mass index. We conclude that scintigraphic evidence of LVH should be reported when RVG studies are interpreted.

Effect of gallium nitrate therapy on Ga-67 scintigraphic detection of lymphoma: case report.

Ga-67 and abdominal CT scans of a 72-year-old woman who had malignant lymphoma before, during, and after gallium nitrate/hydroxyurea combination therapy are presented. Disappearance of Ga-67 uptake by the tumor during this treatment despite continuing CT evidence of disease and reappearance of Ga-67 scan abnormalities after cessation of therapy suggests that caution should be exercised when interpreting results of Ga-67 scintigraphy for the detection of tumor viability during gallium nitrate/hydroxyurea therapy.

In-111 WBC imaging of osteomyelitis in patients with underlying bone scan abnormalities.

One hundred seven combined In-111 WBC/Tc-99m MDP scans performed on 87 patients with a high clinical suspicion of osteomyelitis were retrospectively reviewed. An 86% sensitivity and a 94% specificity for detecting osteomyelitis were found. In addition, patients were grouped into one of five clinical settings for more detailed analysis: diabetic osteoarthropathy, previous arthroplasty, fracture, overlying skin ulcer, and other etiology. Forty-seven studies were performed while patients received antibiotic therapy without loss of sensitivity for detecting osteomyelitis. Results obtained with scintigraphy compared favorably to other imaging and laboratory studies used to detect osteomyelitis. In conclusion, the combined In-111 WBC/Tc-99m MDP scan is a very sensitive and specific method to detect osteomyelitis in patients with concurrent diabetic osteoarthropathy, fracture, postoperative healing, and overlying skin ulcer. Antibiotic treatment does not appear to adversely affect the sensitivity of these scans.