Novel use of gamma correction for precise (99m)Tc-HDP pinhole bone scan diagnosis and classification of knee occult fractures

Resumption of school after lockdown in COVID-19 pandemic: Three case reports

BACKGROUND

Students in the 9th grade of junior high school in Changsha were under a 75 d lockdown due to the coronavirus disease 2019 (COVID-19) pandemic. After the resumption of school post-lockdown, the 9th grade students in Changsha faced the entrance physical examination test for senior high school.

CASE SUMMARY

We report on 3 cases of occult fracture on the same site in adolescents of the same grade since resumption of school after the lockdown from the COVID-19 pandemic. Three students in the 9th grade of junior high school who were facing the physical examination in 2 wk were diagnosed with an occult fracture of the distal femur.

CONCLUSION

It is recommended that the students, parents, education providers and policy makers should all pay attention to the physical exercise of students when the resumption of school after lockdown occurs and they should be aware of occult fractures when the adolescents have pain after physical exercise.

KSNM 60 in General Nuclear Medicine: the Old Dream Comes True

Since the establishment of the Korean Society of Nuclear Medicine (KSNM) in 1961 by Professor Munho Lee, the KSNM has been progressing in various medical fields. Many papers have been published in the Korean Journal of Nuclear Medicine (KJNM), the official journal of KSNM, since 1967 and other domestic/international journals. Here, we tried to highlight the academic activities of KSNM members from the perspective of general nuclear medicine. After the introduction of the ⁹⁹Mo/^99mTc generator, general nuclear medicine has widened the field of clinical application with the advancement of imaging technology and emerging new radiopharmaceuticals; however, there have been many ups and downs. Treatment, as well as diagnosis, was a major concern in Korean nuclear medicine. With the recent advent of single-photon emission computed tomography/computed tomography, we hope that our old dream (diagnosis and treatment under the same principle of nuclear medicine) comes true.

Morphobiochemical diagnosis of acute trabecular microfractures using gamma correction Tc-99m HDP pinhole bone scan with histopathological verification

We prospectively performed gamma correction pinhole bone scan (GCPBS) and histopathologic verification study to make simultaneous morphobiochemical diagnosis of trabecular microfractures (TMF) occurred in the femoral head as a part of femoral neck fracture.Materials consisted of surgical specimens of the femoral head in 6 consecutive patients. The specimens were imaged using Tc-99m hydroxymethylene diphosphonate (HDP) pinhole scan and processed by the gamma correction. After cleansing with 10% formalin solution, injured specimen surface was observed using a surgical microscope to record TMF. Morphological findings shown in the photograph, naive pinhole bone scan, GCPBS, and hematoxylin-eosin (H&E) stain of the specimen were reciprocally correlated for histological verification and the usefulness of suppression and enhancement of Tc-99m HDP uptake was biochemically investigated in TMF and edema and hemorrhage using gamma correction.On the one hand, GCPBS was able to depict the calcifying calluses in TMF with enhanced Tc-99m HDP uptake. They were pinpointed, speckled, round, ovoid, rod-like, geographic, and crushed in shape. The smallest callus measured was 0.23 mm in this series. On the other hand, GCPBS biochemically was able to discern the calluses with enhanced high Tc-99m HDP uptake from the normal and edema dipped and hemorrhage irritated trabeculae with washed out uptake.Morphobiochemically, GCPBS can clearly depict microfractures in the femoral head produced by femoral neck fracture. It discerns the microcalluses with enhanced Tc-99m HDP uptake from the intact and edema dipped and hemorrhage irritated trabeculae with suppressed washed out Tc-99m HDP uptake. Both conventional pinhole bone scan and gamma correction are useful imaging means to specifically diagnose the microcalluses naturally formed in TMF.

Pixelized Measurement of (99m)Tc-HDP Micro Particles Formed in Gamma Correction Phantom Pinhole Scan: a Reference Study

PURPOSE

Currently, traumatic bone diseases are diagnosed by assessing the micro (99m)Tc-hydroxymethylene diphosphonate (HDP) uptake in injured trabeculae with ongoing osteoneogenesis demonstrated by gamma correction pinhole scan (GCPS). However, the mathematic size quantification of micro-uptake is not yet available. We designed and performed this phantom-based study to set up an in-vitro model of the mathematical calculation of micro-uptake by the pixelized measurement.

METHODS

The micro (99m)Tc-HDP deposits used in this study were spontaneously formed both in a large standard flood and small house-made dish phantoms. The processing was as follows: first, phantoms were flooded with distilled water and (99m)Tc-HDP was therein injected to induce micro (99m)Tc-HDP deposition; second, the deposits were scanned using parallel-hole and pinhole collimator to generally survey (99m)Tc-HDP deposition pattern; and third, the scans underwent gamma correction (GC) to discern individual deposits for size measurement.

RESULTS

In original naïve scans, tracer distribution was simply nebulous in appearance and, hence, could not be measured. Impressively, however, GCPS could discern individual micro deposits so that they were calculated by pixelized measurement. Phantoms naturally formed micro (99m)Tc-HDP deposits that are analogous to (99m)Tc-HDP uptake on in-vivo bone scan. The smallest one we measured was 0.414 mm. Flooded phantoms and therein injected (99m)Tc-HDP form nebulous micro (99m)Tc-HDP deposits that are rendered discernible by GCPB and precisely calculable using pixelized measurement.

CONCLUSIONS

This method can be used for precise quantitative and qualitative diagnosis of bone and joint diseases at the trabecular level.

Gamma correction 99mTc-hydroxymethylene diphosphonate pinhole bone scan diagnosis and histopathological verification of trabecular contusion in young rats

The aim of this rat experiment using gamma correction pinhole bone scan (GCPBS) was two-fold: first, to confirm whether specific unwashed micro Tc-hydroxymethylene diphosphonate (Tc-HDP) uptake occurs in trabecular contusion (TC) and washed out uptake occurs in edema and/or hemorrhage-irritated trabeculae, and, second, to histopathologically identify the tissue in which the Tc-HDP uptake is unwashed. Five young Sprague-Dawley rats were used for the contusion model and one rat was used as a control. Trauma was inflicted on the femoral shaft with a free-falling iron ball. The presence of injury was confirmed by means of Tc-HDP pinhole bone scan and radiography with built-in scales. All rats were carefully killed for histopathologic verification. The size and shape of the unwashed high Tc-HDP uptake in TC were assessed on a 50-fold magnified GCPBS (mGCPBS), and the findings were compared with those of hematoxylin eosin (H&E) stain findings. mGCPBS showed TC with osteoblastic rimming and high unwashed Tc-HDP uptake. H&E stain findings showed osteoblastic rimming. The smallest TC was 0.03 mm in transaxial diameter on both mGCPBS and H&E stain findings. The four shapes of TC were bar-like, round, ovoid, and pinpointed in the longitudinal, oblique, and transaxial sections. The size and shape shown on mGCPBS and H&E stain findings were in good accord, demonstrating that TC was coated with osteoblastic rimming, which is pathognomonic of contusion. This sign was not seen for the control rat. mGCPBS is useful in the diagnosis of TC because osteoblastic rimming, typically stained in the base, is marked with unwashed high Tc-HDP uptake.

Size measurement of the thyroid gland on a magnified pinhole thyroid scan using an ultrasonic device measuring distance from the pinhole to the thyroid gland

PURPOSE

Pinhole has been used for magnification of gamma camera images and is valuable for imaging of small organs, such as thyroid; however, size of the organ cannot be measured on the image due to variable degree of magnification by distance between the pinhole and the organ. The aim of this study was to develop a true size measuring system (TSM system) on magnified pinhole thyroid scan using an ultrasonic sensor.

METHODS

An ultrasonic device capable of measuring the distance from the pinhole to the skin overlying the thyroid gland was manufactured using a ~40 kHz piezoelectric-transducer-based sensor, and its accuracy was tested. An interface program was developed and fused with the ultrasonic device for development of the TSM system. Accuracy of the TSM system for measuring size was tested with phantom images and 35 thyroid scans.

RESULTS

The ultrasonic device accurately measured the distance from the pinhole to the skin over the thyroid gland and the measured values were highly reproducible (6 cm; 6.02 ± 0.04 cm, 8 cm; 8.00 ± 0.05 cm, 10 cm; 10.00 ± 0.05 cm). Distance on the phantom image corrected by the TSM system was almost the same as the true distance. Size of the thyroid on the pinhole image was larger (+67.3 to 103.1 %) than the true thyroid size on the parallel-hole image and the magnification decreased by increase of the distance between the pinhole and the skin over the thyroid gland. However, size of the thyroid obtained using the TSM system was almost equal (-2.1 to +3.6 %) to the true thyroid size on the parallel-hole image.

CONCLUSIONS

We developed the TSM system for magnified pinhole images using a distance measuring ultrasonic sensor. Size of the thyroid on the magnified pinhole image obtained using the system was almost the same as the true thyroid size. The TSM system can be applied to obtain accurate size of the thyroid gland or lesions in the thyroid gland on pinhole thyroid scan.

Use of gamma correction pinhole bone scans in trauma

(99m)Tc-hydroxydiphosphonate (HDP) bone scanning is a classic metabolic nuclear imaging method and the most frequently performed examination. Clinically, it has long been cherished as an indispensable diagnostic screening tool and for monitoring of patients with bone, joint, and soft tissue diseases. The HDP bone scan, the pinhole scan in particular, is known for its ability to detect increased, decreased, or defective tracer uptake along with magnified anatomy. Unfortunately, however, the findings of such uptake changes are not specific in many traumatic bone disorders, especially when lesions are minute and complex. This study discusses the recently introduced gamma correction pinhole bone scan (GCPBS), emphasizing its usefulness in the diagnosis of traumatic bone diseases including occult fractures; cervical sprains; whiplash injury; bone marrow edema; trabecular microfractures; evident, gaping, and stress fractures; and fish vertebra. Indeed, GCPBS can remarkably enhance the diagnostic feasibility of HDP pinhole bone scans by refining the topography, pathologic anatomy, and altered chemical profile of the traumatic diseases in question. The fine and precise depiction of anatomic and metabolic changes in these diseases has been shown to be unique to GCPBS, and they are not appreciated on conventional radiographs, multiple detector CT, or ultrasonographs. It is true that MR imaging can portray proton change, but understandably, it is a manifestation that is common to any bone disease.

Depiction of Nidi and Fibrovascular Zones of Osteoid Osteomas Using Gamma-Correction Tc-99m HDP Pinhole Bone Scan and Conventional Radiograph, and Correlation with CT, MRI, and PVC Phantom Imaging

PURPOSE

For the precise imaging diagnosis of osteoid osteoma (OO), the identification of the nidus and fibrovascular zone (FVZ) is essential. However, the latter sign has received little attention because it is difficult to demonstrate. We applied the recently introduced gamma correction (GC) to depict the FVZ on pinhole bone scan (PBS), conventional radiography (CR), and computed tomography (CT). Non-gamma correction MRI was also analyzed for reference.

METHODS

Ten patients with histologically proven diagnoses of OO were enrolled in this retrospective study. PBS, CR, and CT were processed by GC to demonstrate the nidi and FVZ as distinct yet integrating components of OO. PBS was performed using a 4-mm pinhole collimator 3 h after iv injection of 925 to 1,110 MBq (25 to 30 mCi) of Tc-99m HDP, and anteroposterior and mediolateral CR and transverse CT were taken according to the standard technique. MRI sequences included T1- and T2-weighted images. For gamma correction, we utilized the Photo Correction Wizard program of ACD Photo Editor v3.1. A team of three qualified nuclear physician-radiologists, two nuclear physicians, and one MRI specialist read bone scans, radiographs, and MRIs of OO according to each specialty, and orthopaedic aspects and histology were reviewed by one qualified orthopedic surgeon and two qualified pathologists, respectively. Each observer first read the images separately with basic information about the aim of the study given and then in concert. Interpretive disagreement was settled by discussion and consensus.

RESULTS

On pinhole scan, nidi were presented as areas of intense tracer uptake in all cases, and, importantly after GC, a thin ring-like zone with lower tracer uptake became visible in seven out of ten cases. GCCR also revealed a thin lucent zone that circumscribed the nidi in six out of ten cases and GCCT in two of four cases. MRI, without GC, presented nidi with high signal in the center and a thin ring-like zone with low signal in the periphery in five out of six cases. Ring-like zones were 1-2 mm in thickness and circumscribed the nidus as an integrated part and, hence, were morphologically interpreted as FVZ. Histologically, the presence of a variously mineralized FVZ was confirmed in four cases, but individual locus-by-locus image-histology correlation could not be accompolished because specimens were fragmentary. In the FVZ, tracer uptake was lower than in nidi, presumably reflecting that bone metabolism in the two parts differs as in their histology. Statistically, no significant correlation existed between the duration of symptoms and imaging demonstrability of the FVZ (Spearman's test r = -0.057, p = 0.877), but parallelism existed in the demonstrability of the FVZ among GC PBS, CR, and CT, and non-correction MRI.

CONCLUSIONS

GC was useful to enhance the resolution of PBS, CR, and CT in OO so that both the nidi and FVZ were separately imaged. The use of CG PBS and CR in combination is recommended for the specific diagnosis of OO with information about bone metabolism and anatomical characteristics. PBS and CR are economical and widely available.