Feasibility and safety of endoscopic evaluation of gastric emptying.

BACKGROUND AND STUDY AIMS: Scintigraphy is the currently accepted method for evaluation of gastric emptying. Although quantitative, this method is complicated, time-consuming, and costly. If a simple endoscopic technique was available for those instances when quantification of an emptying abnormality is not needed, the same clinical information could be obtained in less time and with resource savings. Our aims in this study were therefore to assess the technical feasibility, tolerability, and safety of unsedated transnasal esophagogastroscopy (T-EG) as a technique for qualitative assessment of gastric emptying. METHODS: The study was done in two phases. In the first phase, 18 volunteers (ten men, eight women) underwent T-EG at 4 hours, 5 hours, or 6 hours after ingestion of a standard meal used for scintigraphic evaluation of gastric emptying without radiolabeling. In the second phase, ten volunteers underwent T-EG after scintigraphic imaging had demonstrated complete gastric emptying. RESULTS: Subjects in both phases tolerated the procedure well and completed the study. In the first phase, 13 of 15 volunteers exhibited complete gastric emptying at 6 hours (87%), while two (13%) revealed some particulate matter in the stomach at that time. In the second phase, one of the ten volunteers exhibited a small amount of solid food residue in the stomach despite documentation of scintigraphic complete emptying. CONCLUSIONS: Evaluation of gastric emptying by unsedated T-EG is both feasible and safe. In healthy, asymptomatic individuals, complete gastric emptying of solid food may take as long as 6 hours.

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.

Detection of osteomyelitis in the neuropathic foot: nuclear medicine, MRI and conventional radiography.

The diagnostic efficacy of (1) combined three-phase bone scintigraphy and In-111 labeled WBC scintigraphy (Bone/WBC), (2) MRI, and (3) conventional radiography in detecting osteomyelitis of the neuropathic foot was compared. Conventional radiography was comparable to MRI for detection of osteomyelitis. MRI best depicted the presence of osteomyelitis in the forefoot. Particularly in the setting of Charcot joints, Bone/WBC was more specific than conventional radiography or MRI.

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.

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.

Appropriateness of imaging procedure requests: do radiologists agree?

OBJECTIVE: We explored the agreement among radiologists in their evaluation of the appropriateness of individual requests for imaging procedures. MATERIALS AND METHODS: We reviewed 318 noninterventional CT, sonographic, MR imaging, and nuclear medicine procedures ordered at a general internal medicine clinic during 8 months in 1995. Five subspecialty radiologists used data from the radiology request from and clinic notes to independently rate the appropriateness of each requested imaging procedure on a four-point scale. The radiologists were unaware of the results achieved by each procedure. Each case was reviewed by at least three radiologists, of whom at least one had relevant subspecialty expertise. Agreement among radiologists was analyzed using Cohen's kappa statistic and weighted kappa statistics and Cronbach's alpha statistic. RESULTS: Nonchance agreement (kappa) was .19 +/- .05; weighted kappa was .24 +/- .05. Interrater agreement was significantly greater than that expected from chance alone (p < .01). The composite score, defined as the average of the radiologists' scores for each case, showed moderate reliability, as evidenced by a value for Cronbach's alpha of 70. CONCLUSION: In the absence of explicit criteria, we found modest but statistically significant agreement among radiologists about the appropriateness of individual requests for imaging procedures. The disagreement among radiologists highlights the importance of developing well-reasoned, explicit criteria by which to judge the appropriateness of diagnostic radiology procedures. Further study is needed to elucidate the relationship between appropriateness and actual patient outcomes.

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.

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.

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.

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.

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.

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.

Pedal radiocolloid lymphoscintigraphy in demonstration of a post-surgical lymphatic leak.

Radiocolloid lymphoscintigraphy is a very effective diagnostic procedure for dynamic evaluation of lymphatic flow. In this case report, the use of radiocolloid lymphoscintigraphy in detection of a post-surgical lymphatic leak is presented. Dynamic pedal lymphoscintigraphy with Tc 99m-antimony trisulfide colloid clearly demonstrated the site of the leak.

High-resolution bone scintigraphy of the adult wrist.

Bony anatomic landmarks of the wrist (e.g., pisiform, hook of hamate, radioulnar joint, and styloid processes of the radius and ulna) were routinely identified in 28 adult patients examined for wrist pain. With the wrists prone and immobilized, bone scintigrams were obtained for 500,000 counts with an asymmetric (133 to 161 keV) Tc-99m energy window and either a converging (best choice) or straight-bore, high-resolution collimator. High-resolution scintigraphy precisely localized degenerative joint disease (nine patients), scaphoid fractures (five), pisiform fracture (one), lunate avascular necrosis (one), radioulnar arthritis (one), septic or inflammatory arthritis (six), ulnocarpal impingement (two), and reflex sympathetic dystrophy syndrome (two). Images obtained palm down with the wrist in ulnar deviation helped identify increased uptake within the scaphoid. Fracture and significant bone or joint disease were excluded in one patient.

Increased sacroiliac joint uptake after lumbar fusion and/or laminectomy.

Of 753 adult patients undergoing SPECT and planar bone scintigraphy for the evaluation of low back pain, 43 (6%) showed either unilateral or bilateral increased sacroiliac joint (SIJ) uptake. Five of the 58 abnormal joints were only identified with SPECT (9%), whereas 20 of the 58 abnormal joints were much more convincingly demonstrated by SPECT (34%). Fifteen of the 43 patients with increased SIJ uptake had undergone prior lumbar laminectomy and/or spinal fusion. Such spinal surgery can increase impact loading on the SIJ, leading to mechanical overload and sacroiliitis. Degenerative joint disease, trauma, or other benign pathology accounted for the remaining patients with increased SIJ uptake. The authors conclude that for patients with a history of lumbar spinal fusion and/or laminectomy, increased SIJ uptake usually is caused by altered spinal mechanics rather than malignancy or infection.

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.