Interpretation Of Bone Scans Research Articles

A new computer-based decision-support system for the interpretation of bone scans

To develop a completely automated method, based on image processing techniques and artificial neural networks, for the interpretation of bone scans regarding the presence or absence of metastases. A total of 200 patients, all of whom had the diagnosis of breast or prostate cancer and had undergone bone scintigraphy, were studied retrospectively. Whole-body images, anterior and posterior, were obtained after injection of 99mTc-methylene diphosphonate. The study material was randomly divided into a training group and a test group, with 100 patients in each group. The training group was used in the process of developing the image analysis techniques and to train the artificial neural networks. The test group was used to evaluate the automated method. The image processing techniques included algorithms for segmentation of the head, chest, spine, pelvis and bladder, automatic thresholding and detection of hot spots. Fourteen features from each examination were used as input to artificial neural networks trained to classify the images. The interpretations by an experienced physician were used as the 'gold standard'. The automated method correctly identified 28 of the 31 patients with metastases in the test group, i.e., a sensitivity of 90%. A false positive classification of metastases was made in 18 of the 69 patients not classified as having metastases by the experienced physician, resulting in a specificity of 74%. A completely automated method can be used to detect metastases in bone scans. Future developments in this field may lead to clinically valuable decision-support tools.

Focally Increased Activity in the Lateral Aspect of the Mid Cervical Spine on Bone Scintigraphy Is Almost Always Benign in Nature

Abnormal bone scan findings in the spine are often nonspecific. The confidence level for the differential diagnosis between metastases and benign or degenerative changes may vary depending on their appearance, location or intensity. The recognition of a specific pattern for certain benign conditions and its subcategorization will increase the credibility of bone scan interpretation while retaining a high level of sensitivity. We report one such finding, focally increased activity on the lateral side of the cervical spine on the posterior view, most common at the C3-C5 level ("mid-cervical-lateral-focus"). Of 481 patients with various cancers who had at least 2 whole-body bone scans, 6 months or more apart, 41 patients were judged to show this characteristic "mid-cervical-lateral-focus" on at least one scan. Final diagnosis (metastasis vs. benign) for each "mid-cervical-lateral-focus" was made based on clinical grounds and serial bone scans. The bone scan showed definite multiple metastases in 15 patients, and the differential diagnosis for the "mid-cervical-lateral-focus" was already clinically irrelevant in these patients. Nevertheless, the "mid-cervical-lateral-focus" was finally judged to be benign in 14 of these 15 patients and in all remaining 26 patients without other obvious metastases. The only "mid-cervical-lateral-focus" judged to be a metastatic focus was not only clinically redundant, but also the most intense among all the "mid-cervical-lateral-foci." in this series (too intense to be interpreted as benign). The typical "mid-cervical-lateral-focus" pattern is extremely unlikely to represent metastases (virtually 0% in patients without other obvious metastases). This knowledge helps exclude metastases on bone scans.

Interobserver Reproducibility in the Interpretation of Bone Scans From Patients Suspected of Having Reflex Sympathetic Dystrophy

This work was undertaken to identify scintigraphic patterns obtained in patients suspected of having reflex sympathetic dystrophy (RSD), now often referred to as complex regional pain syndrome, whose interpretations could be difficult. Ten patients had bone scans because of clinical suspicion of RSD in the lower legs. They were selected retrospectively to have a wide sample of scintigraphic patterns. The radionuclide images and a multiple-choice questionnaire were presented as a PowerPoint file that was sent electronically on the Internet to 54 Belgian nuclear medicine physicians. They had to determine whether the images were in favor of the diagnosis of RSD. Twenty-eight answers (52%) were received. There was near-complete interobserver agreement for perfectly normal scans, for scans showing diffuse uptake with enhancement of periarticular activity, and for scans showing only focal hyperactivity at the site of previous trauma. Results were more discordant when the hyperactivity was mild and when there was a diffuse hypoactivity, with or without focal hyperactivity. This study shows that using very simple methodology, it is possible to identify some scintigraphic patterns in which there is disagreement among observers and whose interpretations vary. As the results are returned to the participants, they can compare their own interpretations with those of their peers. This aspect could be useful in continuing education in medical imaging.

Unusual urinary bladder accumulation in bone scan

B ONE SCINTIGRAPHY is the most commonly performed nuclear medicine procedure, applied to a variety of osseous abnormalities. However, the extraskeletal uptake of a boneseeking agent is often an unexpected finding. Therefore, it is important that the causes of extraskeletal accumulation of bone-seeking agent be kept in mind. The recognition of such conditions will help interpretation of bone scans without mistakes. We report a rare case of a urinary bladder stone that was incidentally found as a pelvic accumulation of bone scan agent.

Correlation between bone scan findings and collagenase activities in patients with breast cancer.

This study correlates nuclear bone scan findings and measurements of type IV collagenases for the evaluation of bony metastasis in patients with proven breast cancer. The authors retrospectively evaluated the final diagnosis of a bone scan and the results of an immunohistochemical staining for 92 kDa and 72 kDa type IV collagenases in, respectively, 30 and 30 patients with metastatic breast cancer, and, respectively, 27 and 26 patients with primary breast cancer. The immunohistochemical staining was performed with tissue specimens obtained from a primary or metastatic breast tumor lesion. The amounts of the enzyme were graded from 0 to 4 and scored by multiplication with the percentage of tumor cells. The confidence of bone scan interpretation also was scored from 1 to 5 with increasing probability. There was a significant difference in enzyme scores between patients with and without metastases. Patients with < 170 92 kDa (26 of 27), 72 kDa (26 of 26) type IV collagenase, showed no active bony, lung, or liver metastases. However, there were variable bone scan findings in patients with a > 200 enzyme score. Bone scan provides no additional benefit in breast cancer patients with a type IV collagenase score of < 170. A bone scan is necessary to confirm, localize, or followup bony metastases in patients with an enzyme score of > 200.

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.

Abnormal Scrotal Finding on Bone Imaging Increased Radioactivity in a Hemi-Scrotum Due to Malignant Lymphoma

An incidental photopenic area in the scrotum may be found on bone scintigraphy; such a lesion can be due to a benign disease (hydrocele). In contrast, increased activity of the hemi-scrotum on bone scintigraphy may indicate a malignant lesion. A 68-year-old man with enlargement of the right scrotum was found to have increased radioactivity in the right scrotum occupying two thirds of the scrotum on an anterior bone scan. On ultrasound examination, this scrotal enlargement showed diffuse hypoechoic density in the right scrotum. The patient underwent right orchiectomy and resection of right spermatic cord; pathologic examination confirmed malignant lymphoma with hematopoietic origin. Bone scan interpretation should include observable asymmetrical soft tissue activity of the scrotum to depict scrotal abnormality

Periarticular bone sites associated with traumatic injury: false-positive findings with In-111-labeled white blood cell and Tc-99m MDP scintigraphy.

The authors evaluate the reliability of combined indium-111-labeled white blood cell (WBC) and technetium-99m methylene diphosphonate (MDP) bone scan interpretations at sites of suspected periarticular osteomyelitis with radiographic evidence of adjacent traumatic arthropathy. A review of all orthopedic patients who underwent In-111 WBC-Tc-99m MDP scintigraphy over a 7-year period revealed a subset of 32 such cases that also included results of bone-biopsy cultures. Twenty-eight patients had a history of traumatic intraarticular injury, and four had periarticular fracture malunion or nonunion. Compared with intraoperative culture results, blinded In-111 WBC-Tc-99m MDP scan interpretations included four true-positive, 17 true-negative, and 10 false-positive results, and one false-negative result. The predictive values for positive and negative scans were 28% and 94%, respectively. A high prevalence of false-positive In-111 WBC-Tc-99m MDP scans may occur at periarticular sites of patients with associated traumatic arthropathy. This reduces the specificity of this technique for osteomyelitis, making culture confirmation of positive scans necessary. A negative scan is highly predictive of negative culture results at these sites.

Total Bone Uptake in Management of Metastatic Carcinoma of the Prostate

The status of patients with skeletal metastases from prostatic carcinoma was determined from a quantitative uptake and retention measurement of the bone scanning radiopharmaceutical 99mtechnetium-methylene diphosphonate. Whole body counts were performed 5 minutes and 24 hours after intravenous administration of 99mtechnetium-methylene diphosphonate, and were expressed as the percentage uptake by the skeleton at 24 hours. Skeletal uptake determinations were done in 29 patients with prostatic cancer (17 with osseous metastases) who were evaluated at 3 to 6-month intervals. Group 1 consisted of patients who responded to therapy and achieved remission, group 2 included patients with relapse or progressive disease, group 3 consisted of those with metastases who were in remission for longer than 6 months and group 4 included those without evidence of any bony metastases. The baseline mean ± standard deviation 24-hour skeletal uptake values were 46.1 ± 12.0 per cent in group 1, 34.3 ± 13.9 per cent in group 2, 27.0 ± 5.9 per cent in group 3 and 28.9 ± 5.5 per cent in group 4. At 3 to 6 months the values in group 1 (responders) decreased by 18 per cent, while those in group 2 (relapse or progression) increased by 19 per cent and those in group 3 (remission) increased by 1.5 per cent.The quantitative 24-hour skeletal uptake test was performed easily, reproducible and at least as useful as concurrent chemical blood tests and subjective bone scan interpretations.

Bone scintigraphic findings related to unilateral mastectomy.

The total body bone scans of 51 breast cancer patients who had received unilateral mastectomies were reviewed to establish the incidence of bone scintigraphic changes related to the surgery. Several features were noted: (a) increased radioactivity in the ribs on the side of the mastectomy in 76% of patients, (b) increased radioisotope uptake in the remaining breast in 36% of patients, (c) increased radioisotope uptake in the soft tissue of the arm on the mastectomy side in 18% of patients. Familiarity with the incidence of these findings may be of use in bone scan interpretation of breast cancer patients.

BONE SCINTIGRAPHIC FINDINGS RELATED TO UNILATERAL MASTECTOMY

The total body bone scans of 51 breast cancer patients who had received unilateral mastectomies were reviewed to establish the incidence of bone scintigraphic changes related to the surgery. Several features were noted: (a) increased radioactivity in the ribs on the side of the mastectomy in 76% of patients, (b) increased radioisotope uptake in the remaining breast in 36% of patients, (c) increased radioisotope uptake in the soft tissue of the arm on the mastectomy side in 18% of patients. Familiarity with the incidence of these findings may be of use in bone scan interpretation of breast cancer patients.

Biokinetics of Bone Tracers by Means of Deconvolution Analysis - Comparison of 99mTc MDP, 99mTc DPD and 99mTc EHDP

Transfer functions of 99mTc methylene diphosphonate (MDP), 99mTc 2,3-dicarboxypropane-1,1-diphosphonate (DPD) and 99mTc ethane-1-hydroxy-1,1-diphosphonate (EHDP) into bone and extravascular fluid of soft tissues were determined in 5 dogs by deconvolution analysis of the time-course of plasma, soft tissue and bone radioactivity. The transfer rates 5 min after injection--indicating the rapid exchange of the tracer between plasma and the extravascular fluid--decrease in the order MDP greater than EHDP greater than DPD (P less than 0.05). The transfer rates into bone--determined from transfer rates between 30 and 60 min--decreased in a different order, i.e. MDP greater than DPD greater than EHDP (P less than 0.05). The fractional bone uptake of diphosphonates estimated from the ratio of early to late transfer rates was slightly greater for DPD than for MDP and EHDP respectively. The difference between DPD and MDP was not significant (P greater than 0.05). The average bone and soft tissue concentrations of DPD 60 min after injection were greater than that of MDP and EHDP due to different plasma concentrations (DPD greater than EHDP greater than MDP), whereas the bone-to-soft tissue ratios decreased in the sequence MDP greater than DPD greater than EHDP (P less than 0.05).--Our results reveal different biokinetics of MDP, DPD and EHDP explaining variations in osseous and soft tissue uptake suggesting that deconvolution analysis could play an important role in bone scan interpretation.

Optimizing the performance and interpretation of bone scans.

Optimizing the performance and interpretation of bone scans.

Skeletal scintigraphy following incidental trauma.

The significance of antecedent trauma in skeletal scintigraphy was assessed in 503 patients, of whom 241 (46%) had prior fracture or tooth extraction. In patients with sufficiently accurate histories for site-by-site analysis, 33 of 131 fracture sites and 16 of 83 dental-procedure sites were positive scintigraphically. In general, the frequency of scan positivity diminished as the interval between trauma and scanning increased, but a significant number of patients showed prolonged uptake at fracture sites. Several patterns of uptake suggested trauma rather than metastatic disease. Knowledge of a history of trauma is often critical in bone scan interpretation.

Extraosseous tumor uptake of 99m Technetium Phosphate Compounds in children with abdominal neuroblastoma

Sixteen patients with abdominal neuroblastoma had 99m Technetium Phosphate Compounds (99m TC-PC) bone scans as a preoperative evaluation for metastatic disease. Ten patients (62%) had extraosseous tumor uptake while six patients (38%) did not. There was no difference in the incidence of tumor calcification, tumor necrosis or hydronephrosis in the two groups. However, VMA levels were significantly higher in the group with extraosseous tumor uptake. Various bone seeking radionuclides are compared to 99m TC-PC and possible mechanism for extraosseous uptake of such radionuclides are postulated. Awareness of the frequency of such uptake should reduce the possibility of errors in the interpretation of bone scans in patients with neuroblastoma.

Scintigraphic diagnosis of primary and metastatic bone tumour by technetium-99m diphosphonate

Diagnosis by serial bone scan was performed on 134 patients with bone tumours using the radioactive isotopes 99m TcEHDP, 99m TcBleo and 67 Ga. 99m TcEHDP bone scan was found to be a highly sensitive screening test in patients with skeletal metastases from malignant bone tumours. Malignant bone tumours demonstrated a marked uptake of all three radiopharmaceuticals. Benign bone tumours did not reveal any abnormal accumulation. The exceptions however were myeloma which showed a decreased uptake in the lesion compared to the background radioactivity and also giant cell tumours which showed an abnormal uptake of all three bone-seeking radiopharmaceuticals. Bone scanning using 99m TcEHDP combined with 99m TcBleo and 67 Ga is a safe, simple and sensitive method for the detection and evaluation of bone tumours. It should, however, be emphasised that there are several pitfalls in the interpretation of bone scans. These include fractures in benign bone tumours and chronic osteomyelitis.

Sources of error in the interpretation of bone scans with 99mTc-diphosphonate (author's transl)

Errors in the interpretation of bone scans with 99mTc-diphosphonate may be due to summation of radio-activity from superimposition of various bone structures. Lesions with increased bone turn-over as well as reactive hyperaemia result in increased uptake. The possibility of extraosseous uptake of diphosphonate must be borne in mind during the evaluation of bone scans. The kidneys and lower urinary tract must be considered. Absent or slight uptake by the kidneys with good demonstration of bone suggests increased diphosphonate uptake by the bones. Special attention should also be paid to zones of decreased uptake, since these are also due to abnormalities in the bone.

Bone scans of the facial bones: Normal anatomy

Some features of facial anatomy have been identified on 99mTc polyphosphate bone scans by a comparison of scans, radiographs, and photographs. 99mTc polyphosphate bone scans are used clinically to show bone injury and increased osteoblastic activity; the primary use is to identify malignancy and other diseases involving bone. A knowledge of normal anatomy is of the utmost importance in the accurate interpretation of bone scans of the face.

False negative bone scans in disseminated metastatic disease.

Three patients had widespread skeletal metastases whose bone scans appeared to be normal. False negative scans were due to symmetrical increased radiopharmaceutical uptake in virtually all bones. Caution must be taken in the interpretation of bone scans in patients with malignant disease which tends to metastasize diffusely (e.g., from the breast, prostate and lung). False negative interpretations may be avoided by viewing at least one radiograph containing bone at the time the scan is interpreted, the most practical being the admission chest film.