Isitman At

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 patients 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.

Painful pseudarthrosis following lumbar spinal fusion: detection by combined SPECT and planar bone scintigraphy

Twenty-six adult patients more than 6-months post-lumbar spinal fusion were studied. Flexion and extension radiographs showing motion or bone scintigrams showing focal areas of increased activity within the fusion mass were considered positive for pseudarthrosis. Patients were classified as either symptomatic or asymptomatic. Among the 15 symptomatic patients, scintigraphy had a sensitivity of 0.78 and a specificity of 0.83 which was superior to the 0.43 sensitivity and 0.50 specificity of radiography. Six of the 11 asymptomatic patients had focal areas of increased activity in the bony fusion mass, possibly reflecting painless pseudarthrosis. Planar imaging was substantially enhanced by SPECT in 14 of the 26 cases. It is concluded that for the patient who remains symptomatic after lumbar spinal fusion, bone scintigraphy with SPECT is of significant value in detecting painful pseudarthrosis.

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.

Correlation of technetium-99m MIBI and thallium-201 retention in solitary cold thyroid nodules with postoperative histopathology

Abstract.A comparative prospective study of technetium-99m methoxyisobutylisonitrile (MIBI) and thallium-201 with early (15 min) and delayed (90 min for MIBI, 3 h for 201Tl) imaging in the differentiation of thyroid lesions is presented. Forty patients with cold thyroid nodules visualised on 99mTc-pertechnetate scan and with dyskaryotic or atypical epithelial cells verified by fine-needle aspiration biopsy underwent MIBI and 201Tl scintigraphy at 3-day intervals. Subsequent thyroidectomies were carried out in all patients. Semiquantitative analysis was performed using a lesion to non-lesion ratio on early (ER) and delayed images (DR). Additionally, a retention index (RI) was calculated using the formula RI=(DR– ER) × 100/ER. The reproducibility of the method for the early and delayed measurements was tested by analysing intra- and inter-observer variability and repeatability coefficients. Histopathologically, the nodules were found to be well-differentiated thyroid cancer in 21 patients and benign in 19 patients. There was no significant difference in the ER between malignant and benign lesions for either 201Tl or MIBI (P>0.05). However, for both agents significant differences were found between malignant and benign lesions with regard to DR (P<0.01 for 201Tl and P<0.001 for MIBI) and RI (P<0.001 for both agents). Statistical comparison of the two agents showed no significant differences (P>0.05) except with regard to DR and RI in malignant nodules (P<0.05). A receiver operating characteristic analysis was performed to determine threshold levels for the differentiation of malignant from benign nodules. Following this analysis, ER, DR and RI levels of 1.03, 1.54 and 2 for MIBI and ≤1.42, 1.24 and 5 for 201Tl were selected. Using these threshold levels, the sensitivity, specificity and accuracy of the study were 90.5%, 36.8% and 65% for ER MIBI, 61.9%, 94.7% and 77.5% for DR MIBI, 95.2%, 89.4% and 92.5% for RI MIBI, 85.7%, 47.3% and 67.5% for ER 201Tl, 80.9%, 73.6% and 77.5% for DR 201Tl, and 90.5%, 94.7% and 92.5% for RI 201Tl. In conclusion, the DR for MIBI and 201Tl is superior to the ER in detecting malignant nodules, and the RI for both MIBI and 201Tl is more valuable than the DR in differentiating malignant from benign thyroid nodules.

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.

Low dose dobutamine echocardiography is more predictive of reversible dysfunction after acute myocardial infarction than resting single photon emission computed tomographic thallium-201 scintigraphy

To directly compare dobutamine echocardiography and resting single photon emission computed tomographic (SPECT) thallium-201 (Tl-201) scintigraphy for the detection of reversible dysfunction, 64 patients underwent dobutomine echocardiography (baseline, low dose 5 and 10 mg/kg/min, and peak dose), rest Tl-201 scintigraphy (3 mCi - 15 minute and 3- to 4-hour SPECT imaging), and coronary angiography during the first week after acute myocardial infarction. Follow-up echocardiography was performed 4 to 8 weeks after discharge. Wall thickening improved at follow-up in 52% (207 of 399) of the dysfunctional segments. By receiver operating characteristic analysis, biphasic responses and sustained improvement during dobutamine echocardiography were more accurate (p < 0.01) than Tl-201 uptake by SPECT scintigraphy for reversible dysfunction. The greater accuracy of dobutamine echocardiography resulted from higher accuracy in akinetic segments, Q wave infarction, and multivessel coronary artery disease. In conclusion, dobutamine echocardiography was more accurate than resting SPECT Tl-201 scintigraphy for reversible dysfunction after acute myocardial infarction.

False-negative bone imaging due to etidronate disodium therapy

A 77-year-old man wilh prostate cancer was serially evaluated for bone metastases using Tc-99m methylene disphosphonate (Tc-99m MOP) both on and off treatment with etidronate disodium (EHDP). While the patient was receiving the medication only minimal bony uptake ot 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.

Technetium-99m sestamibi uptake in human breast carcinoma cell lines displaying glutathione-associated drug-resistance

An in vitro study was designed to evaluate the uptake of sestamibi (MIBI) in P-glycoprotein (Pgp) and glutathione-associated (GSH) multidrug-resistant (MDR) cell lines. MIBI uptake was studied in various human breast carcinoma cell lines, i.e. in wild-type (MCF7/wt) cells, in adriamycin-resistant (MCF7/adr) cells which express Pgp and in melphalan-resistant (MCF7/mph) cells with increased levels of GSH. The effects of buthiomine sulphoximine (BSO) and verapamil on MIBI uptake were also studied in the MCF7/mph and MCF7/adr cells respectively. The cells were incubated for 1 h with a dose of 0.1 MBq thallium-201 and technetium-99m MIBI. Both MIBI and201Tl uptakes were higher for MCF7/mph cells than for the other cells studied. The mean MIBI uptake in MCF7/adr cells was significantly lower than that in MCF7/wt cells (1.9%±0.5% vs 3.1%.0.6%;P <0.01). Verapamil treatment increased the MIBI uptake in MCF7/adr cells (to 2.6%.0.3%;P <0.05). Treatment of MCF7/mph cells with BSO resulted in a significant reduction in GSH content (from 243.2±81.1 nmoUmg protein to 17.6±4.4 nmol/mg protein;P <0.001). However, MIBI uptake in BSO-treated and untreated MCF7/mph cells was similar (4.43%±0.5% and 5.93%±1.7%, respectively;P >0.1). This study suggests that the uptake of MIBI is not diminished by glutathione-associated drug resistance and that MIBI uptake in a tumour sample does not necessarily indicate that a cancer is sensitive to drugs.

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 patlents with meatastatic ovarian carcinoma, careful review of extraosseous regions on bone scan images may provide valuable diagnostic information.

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.