Accumulation of 99mTc-MIBI in bone marrow

Bone uptake of Tc-99m MIBI in patients with hyperparathyroidism

OBJECTIVE

The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT).

METHODS

Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann-Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated.

RESULTS

Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8 %) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z = -4.34, P < 0.001) and ALP (Z = -3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR = 4.42, P < 0.001) and ALP (OR = 3.21, P = 0.002). Among the 30 patients that underwent bone scintigraphy, 76.7 % patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60 % for detecting MBD.

CONCLUSIONS

Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy.

99mTc-sestamibi scintigraphy to monitor the long-term efficacy of enzyme replacement therapy on bone marrow infiltration in patients with Gaucher disease

Assessing the skeletal response to enzyme replacement therapy (ERT) in Gaucher disease (GD) is problematic. We investigated the reliability of (99m)Tc-sestamibi scintigraphy in monitoring changes in bone marrow involvement induced by ERT.

METHODS

In 52 GD patients, the efficacy of ERT on bone marrow disease was monitored using at least 2 sequential (99m)Tc-sestamibi scans; 17 patients were receiving ERT at enrollment, and 35 were ERT-naïve. We elaborated a dose-response model by statistical analysis based on linear mixed models.

RESULTS

Patients whose marrow disease improved had received a significantly higher ERT dose per month than patients who did not improve. Significantly more patients reached near-disappearance of marrow disease if their disease burden at enrollment had been lower and the duration of clinical signs shorter. The response of the marrow scintigraphic score was more pronounced in ERT-naïve patients. No relevant effect of ERT on marrow disease was observed until platelet count and splenomegaly had improved.

CONCLUSION

Although based on localized evaluation, changes in the (99m)Tc-sestamibi score closely correlated with the main determinants of ERT, with a definite dose-response relationship. The threshold at which ERT induced any improvement in bone marrow disease was 35-36 U/kg/mo; in ERT-naïve patients, the scintigraphic score declined by 1 unit after ERT at 28 U/kg/mo.

Bone marrow uptake in parathyroid scintigraphy is a consequence of extremely high parathyroid hormone levels

OBJECTIVE

We retrospectively evaluated patients with end-stage renal disease (ESRD) who were referred to our department for parathyroid scintigraphy. The aim of this study was to investigate the causes of bone marrow uptake observed on parathyroid scintigraphy.

METHODS

We included 18 ESRD patients (10 F, 8 M; mean, 52 ± 13 years old; range, 45-59) in the study. The disease duration of the patients was mean 7.7 ± 4.7 years. The patients' mean plasma calcium and parathormone (PTH) levels were 9.7 ± 1.4 mg/dL and 1,553.3 ± 691.7 pg/mL, respectively. Dual-phase technetium-99m 2-methoxyisobutyl-isonitrile (Tc-99m MIBI) parathyroid imaging and, if necessary, additional Tc-99m pertechnetate scintigraphy were performed. Quantification of the planar early phase parathyroid images was performed for various regions (sternum, humerus, ribs) with the same size rectangular region of interest (ROI, 176 × 176 pixels). Average counts were compared with paired samples Student's t tests, and P<.05 was considered statistically significant.

RESULTS

Tc-99m MIBI parathyroid imaging revealed parathyroid hyperplasia, adenoma, and ectopic adenoma in 7, 3, and 2 patients, respectively. The other 7 patients had normal scintigraphy results with regard to parathyroid pathologies. Bone marrow uptake in the sternum, ribs, and humerus was observed in 6 patients. The difference between the average quantitative value obtained from the ROIs drawn on the sternum and humerus was also statistically significant compared to patients without bone marrow uptake (P<.05). All 6 patients' exhibited extremely high PTH levels (>2,000 pg/mL; mean, 2,413.7 ± 150 pg/mL) compared to the other 12 patients (mean, 1,342.8 ± 249 pg/mL).

CONCLUSION

Our results show that bone marrow uptake on parathyroid scintigraphy is a consequence of extremely high PTH levels in ESRD patients; no further analysis is required.

Focal MIBI uptake is a better indicator of active myeloma than diffuse uptake

PURPOSE

Technetium-99m 2-methoxyisobutylisonitrile (MIBI) imaging has been proposed as a front-line investigation to detect bone disease both before and after the treatment of myeloma. In this study, we have compared the pattern of MIBI uptake (focal and diffuse) between patients with proven myeloma and a cohort of patients without myeloma, in order to identify the uptake pattern that best correlates with disease activity.

METHODS

Nineteen scans were taken in 16 consecutive patients (nine males and seven females: aged 39-71 yr) with active myeloma. A further 20 scans (10 subjects having MIBI myocardial perfusion scintigraphy and 10 subjects having MIBI parathyroid adenoma localisation studies), comprised the control (non-myeloma) cohort. Scans were evaluated in a double-blinded fashion by two observers for any diffuse skeletal MIBI uptake (homogeneous uptake in spine, sternum and/or long bones), and/or abnormal focal uptake (patchy, focal or tubular uptake in the skeleton or soft tissues).

RESULTS

The pattern of MIBI uptake was significantly different in the myeloma-positive subjects and the control cohort. Focal uptake was highly discriminatory, being seen in 15 of 19 (79%) scans of the myeloma-positive group as opposed to one of 20 (5%) scans of the control group (P < 0.0001). In contrast, diffuse uptake was seen in 17 of 19 (89%) scans in patients with myeloma, and in 11 of 20 (55%) of the control cohort (P = 0.02). Using multiple logistic regression analysis, any focal uptake was significantly predictive for active myeloma (P = 0.0007) but diffuse uptake was not (P = 0.15). Diffuse uptake alone, without focal uptake, was found in four of 19 scans with myeloma and in 10 of 20 without active myeloma, but was not significantly associated with absence of active myeloma (P = 0.06). Using the criteria of Pace et al. for positivity (diffuse activity >50% myocardial activity), we demonstrated improved specificity from 45% to 100%, but significantly impaired sensitivity for presence of myeloma (79% vs. 37%, P = 0.02).

CONCLUSION

Our study thus illustrates that the presence of any focal uptake of MIBI is useful in indicating active myeloma whereas diffuse uptake is not.

Tc-99m MIBI uptake in traumatic vertebral fractures and metastatic vertebral lesions: comparison with Tc-99m MDP

This study compared technetium-99m-hexakis-2-methoxyisobutyl-isonitrile (Tc-99m MIBI) with technetium-99m methylene iphosphonate (Tc-99m MDP) to determine whether Tc-99m MIBI could distinguish vertebral metastases from traumatic vertebral fractures. Twenty patients with traumatic vertebral fracture (and no malignant disease) and 14 patients with metastatic vertebral lesions were evaluated. Three to 4 hours after intravenous injection of Tc-99m MDP, images of the vertebrae in all patients were obtained. Corresponding Tc-99m MIBI images were acquired within 4 days after the Tc-99m MDP bone images were obtained. Computed tomography and magnetic resonance imaging demonstrated 24 vertebral traumatic fractures and 44 vertebral metastases. On conventional bone scans, Tc-99m MDP activity was increased in 92% of vertebral fractures and in 100% of vertebral metastases. However, on MIBI scans, no abnormal findings were observed in the vertebrae with fracture, although increased activity was seen in 73% of vertebral metastases. In this study, traumatic vertebral fractures tended to display no pathologic increases in Tc-99m MIBI uptake, whereas bone metastases usually appeared with high uptake. In light of the excellent specificity of Tc-99m MIBI scans compared with Tc-99m MDP bone scans, imaging studies that use Tc-99m MIBI scans may play an important complementary role in differentiating vertebral metastases from traumatic vertebral fractures.

Role of 99mTc-hexakis-2-methoxyisobutylisonitrile for detecting marrow metastases in childhood solid tumours

AIM

To evaluate the role of 99mTc-hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) for detecting bone marrow metastases in childhood solid tumours, including lymphomas.

METHODS

Twenty-six children (18 males, eight females) were studied. They all had proven malignant solid tumours [Hodgkin's lymphoma (5), non-Hodgkin's lymphoma (3), neuroblastoma (9), Ewing's sarcoma (3), Langerhans cell histiocytosis (4), rhabdomyosarcoma (1) and germ cell tumour (1)] with suspected bone marrow metastases. All patients underwent computed tomography and/or magnetic resonance imaging, 99mTc-MIBI and Tc-methylene diphosphonate bone scans and bone marrow aspiration and/or biopsy. The scintigraphic evaluation of 99mTc-MIBI scans was performed according to the visual assessment of the extent and intensity of uptake. The scintigraphic score, which is the sum of the extent and intensity of uptake, was calculated for each patient. Scores of more than 2 were considered to be positive for bone marrow involvement.

RESULTS

Twenty-seven 99mTc-MIBI scans were studied for 26 patients. Twenty-two 99mTc-MIBI scans were accepted as normal bone marrow. Bone scans were also normal in these patients. Five of the 27 99mTc-MIBI scans had scores of more than 2. Bone marrow cytology revealed bone marrow metastases in these patients.

CONCLUSION

Abnormal 99mTc-MIBI uptake correlated extremely well with bone marrow aspiration/biopsy cytology results. Non-invasive 99mTc-MIBI imaging in children with malignant solid tumours appears to be promising for the evaluation of bone marrow metastases.

Illustrations of abdominal abnormalities on 99mTc tetrofosmin gated cardiac SPECT

BACKGROUND

99mTc tetrofosmin is predominantly cleared by the hepatobiliary system and its scan is analogous to a cholescintigraphy. The radiopharmaceutical may be localized in the bone marrow. During cardiac acquisition, when the area being viewed includes the lower thorax and abdomen, abnormalities of the liver, gallbladder and kidneys, and the radioactivity in the oesophagus, stomach and bowel, as well as bone marrow uptake, can be depicted by routine raw data cine images. Excluding the intrathoracic abnormalities, these abdominal abnormalities are illustrated in this paper.

METHODS AND MATERIALS

Retrospectively, we reviewed the raw data cine images from 566 patients. These images were 180 degrees or 360 degrees rotation and showed the abdominal organs and thoracic cage, including the ribs, sternum and spine. We found 234 abnormalities, which were correlated with radiography, laboratory and clinical findings.

RESULTS

Intra-abdominal abnormalities included bone marrow visualization, 93 occurrences (39.7%); duodeno-gastric (DG) and entero-gastric (EG) reflux, 47 (20.1%); non-visualization of the gallbladder, including possible causes of cholelithiasis, acute cholecystitis, or cholecystectomy, 31 (13.2%); elevation of the right diaphragm and depression of diaphragm, 30 (12.8%); renal abnormalities, including absent kidney, renal atrophy and cyst, 12 (5.1%); splenomegaly, 10 (4.3%); liver, including hepatomegaly and cirrhosis of the liver, eight (3.4%); and breast attenuation resulting in photopenia in the liver, three (1.2%).

CONCLUSIONS

(1) The bone marrow uptake of the vertebrae accounts for almost 40% of the abdominal abnormalities, and is usually concordant with anaemia; (2) DG and EG refluxes represent 20% of abdominal abnormalities; they may have a clinical impact and may or may not interfere with SPECT processes and result in artifacts of the inferior wall of the left ventricle; (3) non-visualization of the gallbladder should prompt a search for cholelithiasis; and (4) benign renal cyst or cirrhosis of the liver could also be demonstrated. These coincidental findings may be included in routine cardiac SPECT reports that may have clinical impact because they give the referring physician the chance to pursue further clinical investigation.

Is technetium-99m-MIBI taken up by the normal pituitary gland? A comparison of normal pituitary glands and pituitary adenomas

PURPOSE

The aim of this study was to compare the behavioral uptake of a normal gland and a pituitary adenoma and to assess the ability to diagnose pituitary adenoma by means of technetium-99m-hexakis-2-methoxy-isobutyl-isonitrile (MIBI) single photon emission computed tomography (SPECT).

METHODS

The study included 15 patients with pituitary adenomas (mean age = 44.0 years, range 19-63) and 15 control subjects (mean age = 50.7 years, range 20-67). SPECT was performed 15 minutes after an intravenous injection of MIBI 600 MBq. The shape and location of MIBI uptake were evaluated on a magnetic resonance (MR) imaging/SPECT registration image. The shape patterns and location were classified as follows: Shape C (circular); LO (longitudinal oval); T/R (triangular or rectangular) and location P (pituitary gland or adenoma); D/C (dorsum sellae and/or clivus).

RESULTS

Analysis of the uptake showed that 10 (67%) adenomas were C, and 5 (33%) were LO. Of the controls, 5 (33%) were C, and 10 (69%) were T/R. With regard to location, all patients with pituitary adenomas were classified as P, and all control subjects (93%) but one showed uptake in the dorsum sellae and clivus (D/C).

CONCLUSION

MIBI was taken up in the dorsum sellae or clivus but not the normal pituitary gland and had a strong affinity for the pituitary adenoma. This result implies that MIBI SPECT may be a useful new auxiliary examination technique for the location diagnosis of pituitary adenoma.

The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in suspected recurrent breast cancer

The aim of this study was to determine the role of technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy in the evaluation of recurrence and metastases in breast cancer patients with mastectomy and/or radiotherapy. A prospective study was designed to assess the accuracy of 99mTc-MIBI scintigraphy in 36 patients (mean age 49 years) with suspected recurrent breast cancer. The scintigraphic studies were correlated with radiological findings and/or with histopathology. At 10-15 min after 740MBq 99mTc-MIBI injection, standard planar images were obtained in prone lateral and anterior supine views and then single-photon emission computed tomography (SPECT) imaging was performed. A whole body imaging was also performed to demonstrate distant metastatic lesions. Totally 52 lesions were evaluated which 19 of them in 9 patients were malignant, while 33 lesions in 27 patients were benign. The sensitivity was 33%, 88% and the specificity was 96%, 93% for planar and SPECT imaging, respectively in loco-regional lesions. Overall, the sensitivity and the specificity of MIBI imaging including whole body were 89%, 81%, in other conventional radiological imaging methods were 95%, 65%, respectively. 99mTc-MIBI scintigraphy using SPECT imaging may provide useful complementary information in patients with suspected recurrence breast cancer.

Detection of minimal residual disease in acute leukemia by Tc-99m MIBI femoral marrow imaging

To determine the potential of Tc-99m MIBI femoral marrow imaging for detecting minimal residual disease in acute leukemia, MIBI images of 68 patients with acute leukemia and 110 control patients were examined. MIBI accumulation was classified into three patterns: not detectable, mild accumulation, and clearly visualized accumulation. Clearly visualized accumulation was interpreted as abnormal. The mean uptake ratio of the femoral marrow to muscle was calculated. Forty-five patients who were in complete remission (CR) at the time of MIBI imaging had a follow-up study (mean interval, 23 months). Clearly visualized accumulation was demonstrated in 35 patients with acute leukemia: in 7 patients before starting induction chemotherapy, in 12 patients after relapse, and in 16 of the 49 patients in the CR group. Mild accumulation was demonstrated in 14 patients in the CR group and in 13 control group patients. No detectable accumulation was observed in 19 patients in the CR group and in 97 control patients. The marrow and muscle uptake ratio of patients before starting chemotherapy (2.29 +/- 0.26) was greater compared with that in patients after relapse (1.78 +/- 0.44, P < 0.02) and in patients with abnormal accumulation despite complete remission (1.84 +/- 0.36, P < 0.01). The uptake ratio in patients with abnormal accumulation despite CR was higher compared with patients with mild accumulation in CR (1.26 +/- 0.13, P < 0.001) and controls (1.23 +/- 0.10, P < 0.001) who had mild accumulation. Fifteen patients with abnormal accumulation despite CR had a markedly greater relapse rate (66.7% > 10.0%, P < 0.005), a higher mortality rate (46.7% > 6.7%, P < 0.01), and shorter remission time (8.7 +/- 10.2 months < 35.9 +/- 20.1 months, P < 0.001) compared with 30 patients without abnormal accumulation in CR. MIBI femoral marrow imaging may be a useful and simple method for monitoring levels of residual leukemic cells. Clearly visualized MIBI accumulation may be a marker for relapse.

Comparison of Tc-99m sestamibi and TI-201 uptake in multiple myeloma

The authors report abnormal Tc-99m sestamibi (MIBI) and TI-201 uptake in a 62-year-old patient with histologically and biochemically proved myeloma. TI-201 imaging was undertaken for tumor evaluation, and 3 days later a Tc-99m MIBI study showed diffuse and focal marrow uptake with focal skull lesions, whereas TI-201 did not show skull lesions. After treatment, follow-up Tc-99m MIBI whole-body imaging was performed and the marrow uptake was decreased.

Tc-99m MIBI localization in bone marrow: a marker of bone marrow malignancy

To determine the potential of Tc-99m MIBI for detecting bone marrow malignancy, MIBI imaging of the femur was evaluated. There was no detectable MIBI activity in 125 of 141 (89%) control patients. Clearly demonstrated focal or tubular MIBI activity indicating intramedullary accumulation was demonstrated in 44 of 45 (98%) patients with proven marrow malignancy: 9 patients with multiple myeloma, 10 patients with malignant lymphoma, 11 patients with acute leukemia, 1 patient with chronic leukemia, and 14 patients with skeletal metastases. No abnormal MIBI activity was observed in the femur in 19 of 22 (86%) patients who had no evidence of malignant involvement in the femoral marrow, in 3 patients with solitary plasmacytomas of the spine, sternum or iliac bone, or in 16 patients with malignant lymphoma. In 12 of 24 patients with acute leukemia in complete remission, no abnormal MIBI accumulation was shown in the femur, but in 12 patients, abnormal accumulation indicating residual leukemic activity was demonstrated. MIBI imaging correlated extremely well with MRI studies; 26 of 28 patients with focal or tubular increased MIBI activity in the femur showed decreased signal on T1-weighted images and a high signal on short inversion recovery images, and 11 patients with no abnormal activity showed a high signal on T1 images. MIBI imaging of the femoral bone marrow may be a new modality for detecting marrow malignancy.